Note: Descriptions are shown in the official language in which they were submitted.
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FLUID TURBINE WITH MOVEABLE FLUID CONTROL MEMBER
BACKGROUND
[0001] The present disclosure relates to shrouded fluid turbines that use an
impeller to generate power from the passage of a fluid stream, such as a wind
stream or a water stream. The fluid turbine contains moveable aerodynamic
components or members that can be used to control the impeller speed or to
minimize dynamic loads experienced in high fluid velocity conditions.
[0002] Conventional horizontal axis wind turbines (HAWTs) used for power
generation have two to five open blades arranged like a propeller, the blades
being
mounted to a horizontal shaft attached to a gear box which drives a power
generator.
The blades generally rotate at a rotational speed of about 10 to 22 rpm, with
tip
speeds reaching over 200 mph. HAWTs will not exceed the Betz limit of 59.3%
efficiency in capturing the potential energy of the wind passing through it.
[0003] A shrouded wind turbine is a type of HAWT. Shrouded turbines comprise
a shroud that surrounds the blades. The ducted nature of the shroud allows a
rotor/stator assembly to be used to capture the wind energy. Generally, the
stator is
upstream of the rotor. Upstream stator vanes direct incident wind onto the
rotor
blades. However, the stator may also be located downstream of the rotor.
[0004] Wind turbines are generally configured to be most efficient within a
given
range of wind speeds. When the fluid load on the turbine is too high (i.e.
high
winds), the wind turbine blades can be stressed beyond their tolerances and
crack or
break.
BRIEF DESCRIPTION
[0005] Disclosed herein are shrouded fluid turbines that include moveable or
mobile components to reduce loads and/or control the impeller speed. Among
other
things, these components assist in generating various amounts of energy and in
controlling fluid flows. This is beneficial such as for keeping the power
generator
within its cut in / cut out range, reducing the possibility of damage to the
turbine.
Other benefits may be set forth below.
[0006] In this regard, disclosed in certain embodiments is a shrouded fluid
turbine
that includes an impeller and a turbine shroud surrounding the impeller. The
impeller
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includes a stator and a rotor. The stator and/or the rotor has one or more
moveable
components/members for controlling the fluid stream in the fluid turbine.
[0007] The stator may be made from a stator hub and one or more of stator
vanes extending radially from the stator hub. The moveable component is part
of at
least one of the stator vanes. The moveable component may include a stationary
member and a first moveable member which are located longitudinally to each
other
along the stator hub. The first moveable member is able to pivot relative to
the
stationary member about a radial axis.
[0008] In some embodiments, the stationary member defines a leading edge of
the stator vane. The stationary member and the first moveable-member are
pivotally
engaged along a back end of the stationary member and a front end of the first
moveable member. The first moveable member defines a trailing edge of the
stator
vane.
[0009] The stator vane may also have a plurality of moveable members, a front
end of each moveable member being pivotally engaged to a back end of another
member. The front end of one moveable member is pivotally engaged to a back
end
of the stationary member.
[0010] In other embodiments, the stationary member defines the leading edge
and a trailing edge of the stator vane. The first moveable member forms a
portion of
an upwind or downwind surface of the stator vane, the radial axis of the first
moveable member being located in a central portion of the stationary member.
In
more specific embodiments, the stator vane has two moveable members. The first
moveable member forms a portion of the upwind surface of the stator vane, and
the
second moveable member forms a portion of the downwind surface of the stator
vane. The radial axes of both moveable members are located in the central
portion
of the stationary member.
[0011] In other embodiments, the stationary member defines the leading edge
and a trailing edge of the stator vane. The first moveable member forms a
portion of
an upwind or downwind surface of the stator vane. The first moveable member is
located along the trailing edge of the stationary member and may be deployed
downstream of the trailing edge of the stator vane. In some embodiments, the
first
moveable member is deployed by rotating about a radial axis which is located
along
the trailing edge of the stationary member. In other embodiments, the first
moveable
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member is deployed by extending longitudinally outwards from the trailing edge
of
the stationary member.
[0012] In particular embodiments, the first moveable member has a nonlinear
edge. For example, the nonlinear edge may have a sawtooth, sinusoidal, or
curved
shape. In other embodiments, the first moveable member may have a plurality of
fluid passages between an upper surface and a lower surface, or may have an
asymmetrical shape along a radial length of the stator vane.
[0013] Also disclosed are embodiments wherein the stator is made up of a
stator hub and one or more stator vanes extending radially from the stator
hub. At
least one of the stator vanes includes the moveable component. The moveable
component may be made from a leading edge member, an upper surface segment,
a lower surface segment, and a trailing edge member. A back end of the leading
edge member is longitudinally engaged with a forward edge of the upper surface
segment and a forward edge of the lower surface segment. A front end of the
trailing
edge member is longitudinally engaged with a rear edge of the upper surface
segment and a rear edge of the lower surface segment. The upper surface
segment
and the lower surface segment can move longitudinally relative to the leading
edge
member and the trailing edge member to change the camber of the stator vane.
Either the leading edge member or the trailing edge member may be fixed to the
stator hub.
[0014] The stator vane may include a plurality of linear motion actuators
located
within either the leading edge member or the trailing edge member. Cables
extend
from the linear motion actuators to an upper surface and a lower surface of
the other
edge member (i.e. the trailing edge member or the leading edge member,
respectively).
[0015] In different embodiments, the stator vane contains a drive pulley
located
within one of the edge members and a cable engaging the drive pulley. Both
free
ends of the cable are attached to one or more fixed points within the other
edge
member. A constant distance exists between the drive pulley and the one or
more
fixed points. The upper surface segment and the lower surface segment engage
the cable on opposite sides of the drive pulley.
[0016] In yet other embodiments, linear motion actuators are used to engage
the
back end of the leading edge member to the forward edge of the upper surface
segment and the forward edge of the lower surface segment, and to engage the
front
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end of the trailing edge member with the rear edge of the upper surface
segment
and the rear edge of the lower surface segment.
[0017] Disclosed in some further embodiments is a rotor that comprises the
moveable component. The moveable component includes a hollow rotor blade (i.e.
a stationary member) and a gate (i.e. a moveable member). An upstream surface
and a downstream surface of the hollow rotor blade each have a fluid passage.
Located within the hollow rotor blade is the gate, which includes an insert
for each
fluid passage operatively connected to a pivoting arm, the pivoting arms
engaging a
weighted member which engages a tension member. The pivoting arms and the
tension member cooperate so that below a given fluid velocity threshold, the
inserts
align with the fluid passages to prevent fluid flow through the fluid
passages, and
above the given fluid velocity threshold, the inserts are removed from the
fluid
passages to create an aperture through the hollow rotor blade. Additionally, a
plurality of inserts may be mounted on a plate that is connected to a pivoting
arm.
[0018] The fluid turbine may further include an ejector shroud that is
substantially
downstream of the turbine shroud and coaxial with the turbine shroud.
[0019] The present disclosure also relates to methods for controlling the load
experienced by an impeller of a fluid turbine. The fluid turbine includes an
impeller
for generating power from a fluid stream, and a turbine shroud surrounding the
impeller. The impeller includes a stator and a rotor. The stator and/or the
rotor
contains a moveable component. The moveable component can be moved between
a first position and a second position to control the load. The motion of the
moveable component may be actively controlled by the user, or the motion may
occur passively (i.e. without explicit instructions from the user) as the
result of a
change in ambient conditions.
[0020] These and other non-limiting features or characteristics of the present
disclosure will be further described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The following is a brief description of the drawings, which are
presented
for the purposes of illustrating the disclosure set forth herein and not for
the
purposes of limiting the same.
[0022] FIG. 1 is a front left perspective view of an embodiment of a shrouded
fluid
turbine of the present disclosure.
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[0023] FIG. 2 is a rear right perspective view of the shrouded fluid turbine
of FIG.
1.
[0024] FIG. 3 is a cross-sectional view of the shrouded fluid turbine of FIG.
1
taken along line 3'-3'.
[0025] FIG. 4 is a smaller view of FIG. 3 showing areas of magnification.
[0026] FIG. 5 and FIG. 6 are magnified views of the mixing lobes of the fluid
turbine of FIG. 4.
[0027] FIG. 7 is a rear view of the shrouded fluid turbine of FIG. 1. The
blades of
the impeller are removed from this figure so that other aspects of the fluid
turbine
can be more clearly seen and explained.
[0028] FIG. 8 is a front view of a turbine stator comprising stator vanes with
a
stationary member and at least one moveable member.
[0029] FIG. 9 is a top view of the stator vane of FIG. 8, having a stationary
member and only one moveable member (i.e. flap).
[0030] FIG. 10 is a cross-sectional view of the stator vane of FIG. 9 with the
flap
located at a zero flap angle.
[0031] FIG. 11 is a cross-sectional view of the stator vane of FIG. 9 with the
flap
located at a positive flap angle.
[0032] FIG. 12 is a CFD generated graph showing the percentage of power
produced by the rotor as a function of the stator flap angle.
[0033] FIG. 13 is an exploded view of a stator vane having an outer cover, a
stationary member, and a plurality of moveable members.
[0034] FIG. 14 is a shrouded fluid turbine mounting a stator having the stator
vane of FIG. 13.
[0035] FIG. 15 is a magnified view of the stator vane mounted on the shrouded
fluid turbine of FIG. 14.
[0036] FIG. 16 is a shrouded fluid turbine mounting a set of stator vanes in a
closed or stowed state.
[0037] FIG. 17 is a magnified view of the stator vane of FIG. 16, illustrating
a
stator having a moveable member (flap) that rotates along the trailing edge of
the
stationary member.
[0038] FIG. 18 is a shrouded fluid turbine showing the stator vanes of FIG. 17
in
an open or deployed state.
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[0039] FIG. 19 is a magnified view of the stator vane of FIG. 18 with the flap
in an
open or deployed state. Here, the flap rotates to the deployed state.
[0040] FIG. 20 is a shrouded fluid turbine showing the stator vanes of FIG. 17
in
an open or deployed state.
[0041] FIG. 21 is a magnified view of the stator vane of FIG. 20 with the flap
in an
open or deployed state. Here, the flap extends out to the deployed state.
[0042] FIG. 22 is a shrouded fluid turbine mounting a variant of the stator
vane of
FIG. 16 in an open or deployed state.
[0043] FIG. 23 is a magnified view of the stator vane of FIG. 22, where the
trailing
edge of the flap has a sawtooth edge.
[0044] FIG. 24 is a shrouded fluid turbine mounting another variant of the
stator
vane of FIG. 16 in an open or deployed state.
[0045] FIG. 25 is a magnified view of the stator vane of FIG. 24, where a
plurality
of fluid passages run through the flap.
[0046] FIG. 26 is a shrouded fluid turbine mounting another variant of the
stator
vane of FIG. 16 in an open or deployed state.
[0047] FIG. 27 is a magnified view of the stator vane of FIG. 26, where the
flap
has an asymmetric shape, such as the triangular shape shown here.
[0048] FIG. 28 is a front view of a shrouded fluid turbine where the flaps on
the
stator vanes are partially deployed.
[0049] FIG. 29 is a side cut-away view of a shrouded fluid turbine mounting
another stator vane.
[0050] FIG. 30 is a magnified view of the stator vane of FIG. 29, which
comprises
two moveable members (i.e. flaps) with a rotational axis in the central
portion of the
stationary member.
[0051] FIG. 31 is a side view of a stator vane having a leading edge member, a
trailing edge member, an upper surface segment, and a lower surface segment.
The
stator vane is depicted in a positive camber position.
[0052] FIG. 32 is a magnified view of the connection between the leading edge
member, upper surface segment, and lower surface segment of FIG. 31.
[0053] FIG. 33 is a side view of the stator vane of FIG. 31 in a neutral
position.
[0054] FIG. 34 is a side view of the stator vane of FIG. 31 in a negative
camber
position.
[0055] FIG. 35 is a perspective view of the stator vane of FIG. 31.
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[0056] FIG. 36 is a magnified view of FIG. 35 showing a method of constructing
the stator vane of FIG. 31.
[0057] FIG. 37 is a cut-away side view of the stator vane of FIG. 31.
[0058] FIG. 38 is a magnified view of FIG. 37 showing another method of
constructing the stator vane of FIG. 31.
[0059] FIG. 39 is a side cross-sectional view of another method of
constructing
the stator vane of FIG. 31.
[0060] FIG. 40 is a side view of another method of constructing the stator
vane of
FIG. 31.
[0061] FIG. 41 is a cut-away side view of a stator using stator vanes of FIG.
31
mounted on a shrouded fluid turbine.
[0062] FIG. 42 is a magnified view of the stator vanes of FIG. 41.
[0063] FIG. 43 is a perspective exterior view of a rotor having fluid passages
and
a moveable component.
[0064] FIG. 44 is a magnified view of a blade of the rotor of FIG. 43 in a
closed
state, with inserts inserted in the fluid passages.
[0065] FIG. 45 is a magnified view of a blade of the rotor of FIG. 43 in an
open
state, with inserts removed from the fluid passages.
[0066] FIG. 46 is a duplicate of the rotor of FIG. 43.
[0067] FIG. 47 is a magnified, cut-away view of the rotor blade.
[0068] FIG. 48 is a side cross-sectional view showing the moveable component
in
the interior of the rotor blade in a closed state.
[0069] FIG. 49 is a side cross-sectional view showing the moveable component
in
the interior of the rotor blade in an open state.
DETAILED DESCRIPTION
[0070] A more complete understanding of the components, processes, and
apparatuses disclosed herein can be obtained by reference to the accompanying
figures. These figures are intended to demonstrate the present disclosure and
are
not intended to show relative sizes and dimensions or to limit the scope of
the
present disclosure.
[0071] Although specific terms are used in the following description, these
terms
are intended to refer to particular structures in the drawings and are not
intended to
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limit the scope of the present disclosure. It is to be understood that like
numeric
designations refer to components of like function.
[0072] The term "about" when used with a quantity includes the stated value
and
also has the meaning dictated by the context. For example, it includes at
least the
degree of error associated with the measurement of the particular quantity.
When
used in the context of a range, the term "about" should also be considered as
disclosing the range defined by the absolute values of the two endpoints. For
example, the range "from about 2 to about 4" also discloses the range "from 2
to 4."
[0073] A Mixer-Ejector Power System (MEPS) provides an improved means of
generating power from fluid streams such as wind currents. A primary shroud
contains an impeller which extracts power from a primary fluid stream. A mixer-
ejector pump is included that ingests flow from the primary fluid stream and
secondary flow, and promotes turbulent mixing. This enhances the power system
by
increasing the amount of fluid flow through the system, reducing back pressure
on
turbine blades, and reducing noise propagating from the system.
[0074] The term "impeller" is used herein to refer to any assembly in which
one or
more blades are attached to a shaft and able to rotate, allowing for the
generation of
power or energy from fluid rotating the blades. Examples of impellers include
a
propeller or a rotor/stator assembly. Any type of impeller may be enclosed
within the
turbine shroud in the fluid turbine of the present disclosure.
[0075] The front of the fluid turbine indicates the direction from which fluid
enters
the fluid turbine. The leading edge of a turbine shroud may be considered the
front
of the fluid turbine, and the trailing edge of an ejector shroud may be
considered the
rear of the fluid turbine. A first component of the fluid turbine located
closer to the
front of the turbine may be considered "upstream" of a second component
located
closer to the rear of the turbine. Put another way, the second component is
"downstream" of the first component.
[0076] The present disclosure relates to a shrouded fluid turbine including an
impeller, a turbine shroud that surrounds the impeller, and an optional
ejector shroud
downstream of and coaxial with the turbine shroud. Mixing elements may be
present
on the trailing edge of the turbine shroud. In particular, the shrouded fluid
turbine
includes one or more moveable mechanisms or members for reducing loads and/or
controlling rotor speed. The members may be present on one or more stator
vanes,
and/or on one or more rotor blades of the impeller.
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[0077] The instant disclosure relates to several findings. First, it was found
that
using a rotor/stator assembly as an impeller in a shrouded fluid turbine
achieves high
efficiency when the stator comprises stator vanes that have moveable
components
allowing the camber of the vanes to be changed. This allows the stator vanes
to
continue directing incident fluid onto the rotor blades in varying fluid
speeds and
conditions. Separately, it was found that various rotor configurations could
also
increase control of the fluid turbine in different fluid velocity conditions.
The
shrouded fluid turbine itself includes a turbine shroud surrounding the
impeller and
sometimes an ejector shroud downstream of and coaxial with the turbine shroud.
The turbine shroud includes a plurality of mixing lobes on a trailing edge,
such that
the trailing edge has a circular crenellated shape. The mixing lobes may
extend into
an inlet end of the ejector shroud.
[0078] The fluid turbine can be any type of shrouded fluid turbine, for
example, a
wind turbine or a water turbine. In this regard, the aerodynamic principles of
a wind
turbine also apply to hydrodynamic principles in a water turbine, etc.
[0079] Initially, it may be helpful to describe a fluid turbine in which the
stators,
rotors, and shrouds of the present disclosure can be used, to provide context
for an
further explanation of their aspects.
[0080] A shrouded fluid turbine is shown in FIGS. 1-7. The shrouded fluid
turbine
100 comprises an aerodynamically contoured turbine shroud 110, an
aerodynamically contoured nacelle body 150, an impeller 140, and an
aerodynamically contoured ejector shroud 120. The turbine shroud 110 includes
a
front end 112 and a rear end 114. The ejector shroud 120 includes an inlet end
122
and an exhaust end 124. Support members 106 connect the turbine shroud 110 to
the ejector shroud 120.
[0081] The impeller 140 surrounds the nacelle body 150. Here, the impeller is
a
rotor/stator assembly comprising a stator 142 having stator vanes 144 and a
rotor
146 having rotor blades 148. The rotor 146 is shown here as being downstream
and
"in-line" with the stator vanes 144. Put another way, the leading edges of the
rotor
blades are substantially aligned with the trailing edges of the stator vanes.
The
impeller is also shown here located at the front end 112 of the turbine
shroud. The
rotor blades are held together by a rotor hub, and the rotor 146 is
rotationally
engaged to the nacelle body 150. In particular embodiments, the stator has
nine
stator vanes 144, and the rotor has seven rotor blades 148. The impeller 140
is
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configured to be exposed to ambient fluid flow. Put another way, in these
embodiments there are no components which hinder the impeller from direct
exposure to ambient fluid flow. The impeller is also a single stage turbine,
and does
not contain multiple stages.
[0082] The nacelle body 150 is connected to the turbine shroud 110 through the
stator 142, or by other means. The nacelle comprises an inlet 154, an outlet
156,
and a central channel 152 between the inlet 154 and the outlet 156 that
extends
through the nacelle body 150. The stator 142 and rotor 144 are shown here as
engaging the nacelle body 150 at the front end 112 of the turbine shroud, or
in other
words at the inlet 154 of the nacelle body. It is contemplated that the
nacelle body
and the stator can be made as one integral piece, or as two separate
components
that are then joined together. The nacelle body can contain the power
generator (not
shown).
[0083] Some variations on the placement of the rotor and stator are not shown
here, but are contemplated as being within the scope of this disclosure. In
one
variation, the stator 142 is downstream of the rotor 144. In another
variation, the
stator 142 and rotor 144 engage the nacelle body 150 at the rear end 114 of
the
turbine shroud (i.e. at the outlet 156 of the nacelle body), or possibly at
the inlet end
122 of the ejector shroud (depending on the length of the nacelle body). In
such
embodiments, the stator may be connected to the ejector shroud 120 instead of
the
turbine shroud 110.
[0084] The turbine shroud has the cross-sectional shape of an airfoil with the
suction side (i.e. low pressure side) on the interior of the shroud. The
turbine shroud
may be configured to provide a rotor inlet velocity within the turbine shroud
of at least
2.5 times the free stream fluid velocity to which the fluid turbine is
exposed. The rear
end 114 of the turbine shroud also has mixing lobes 116. The mixing lobes
extend
downstream beyond the rotor blades. Put another way, the trailing edge 118 of
the
turbine shroud is formed from a plurality of mixing lobes. The rear or
downstream
end of the turbine shroud is shaped to form two different sets of mixing lobes
116.
High energy mixing lobes 117 extend inwardly towards the central axis 105 of
the
mixer shroud. Low energy mixing lobes 119 extend outwardly away from the
central
axis 105. These mixing lobes are more easily seen in FIG. 2.
[0085] A mixer-ejector pump (indicated by reference numeral 101) comprises an
ejector shroud 120 downstream of and coaxial with the turbine shroud 110. In
some
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~l. "M. IVa... vii GVV IVVYY UU I
example embodiments, the mixing lobes 116 may extend downstream and into an
inlet end 122 of the ejector shroud 120. Put another way, the rear end 114 of
the
turbine shroud 110 may extend into the inlet end 122 of the ejector shroud
120. In
accordance with other embodiments, the mixing lobes 116 may be separated from
the inlet end 122 of the ejector shroud 120 by a gap (not shown).
[0086] The turbine shroud's entrance area and exit area will be equal to or
greater
than that of the annulus occupied by the impeller. The internal flow path
cross-
sectional area formed by the annulus between the nacelle body and the interior
surface of the turbine shroud is aerodynamically shaped to have a minimum
cross-
sectional area at the plane of the turbine and to otherwise vary smoothly from
their
respective entrance planes to their exit planes. The ejector shroud entrance
area is
greater than the exit plane area of the turbine shroud.
[0087] Several optional features may be included in the shrouded fluid
turbine. A
power take-off, in the form of a wheel-like structure, can be mechanically
linked at an
outer rim of the impeller to a power generator. The generator may be located
upwind or downwind of the rotor/stator. Sound absorbing material can be
affixed to
the inner surface of the shrouds, to absorb and prevent propagation of the
relatively
high frequency sound waves produced by the turbine. The fluid turbine can also
contain blade containment structures for added safety. The shrouds may have an
aerodynamic contour in order to enhance the amount of flow into and through
the
system. The inlet and outlet areas of the shrouds may be non-circular in cross
section such that shroud installation is easily accommodated by aligning the
two
shrouds. A swivel joint may be included on a lower outer surface of the
turbine for
mounting on a vertical stand/pylon, allowing the turbine to be turned into the
fluid in
order to maximize power extraction. Vertical aerodynamic stabilizer vanes may
be
mounted on the exterior of the shrouds to assist in keeping the turbine
pointed into
the fluid.
[0088] The area ratio of the ejector pump, as defined by the ejector shroud
120
exit area over the turbine shroud 110 exit area, may be in the range of about
1.5 to
about 3Ø The number of mixing lobes can be between 6 and 28. The height-to-
width ratio of the lobe channels may be between about 0.5 and about 4.5. The
mixing lobe penetration may be between about 50% and about 80%. The nacelle
body 150 plug trailing edge angles may be thirty degrees or less. The length
to
diameter (L/D) of the overall fluid turbine may be between about 0.5 and about
1.25.
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[0089] Referring now to FIGS. 3-7, the turbine shroud 110 shown here has a set
of nine high energy mixing lobes 117 that extend inwards toward the central
axis 105
of the turbine. The turbine shroud also has a set of nine low energy mixing
lobes
119 that extend outwards away from the central axis. The high energy mixing
lobes
alternate with the low energy mixing lobes around the trailing edge 118 of the
turbine
shroud. The impeller 140, turbine shroud 110, and ejector shroud 120 are
coaxial
with each other, i.e. they share a common central axis 105.
[0090] The trailing edge 118 of the turbine shroud 110 has a circular
crenellated
shape. The trailing edge can be described as including several inner
circumferentially spaced arcuate portions 181 which each have the same radius
of
curvature. Those inner arcuate portions 181 are evenly spaced apart from each
other. The inner arcuate portions 181 are generally located on an inner circle
192
having radius of curvature 197. Between portions are several outer arcuate
portions
183, which each have the same radius of curvature. The outer arcuate portions
183
are generally located on an outer circle 190 having radius of curvature 195.
The
radius of curvature 197 for the inner arcuate portions 181 is different from
the radius
of curvature 195 for the outer arcuate portions 183, but the inner arcuate
portions
and outer arcuate portions have the same center (i.e. along the central axis
105).
The outer radius of curvature 195 is generally greater than the inner radius
of
curvature 197. The inner arcuate portions 181 and the outer arcuate portions
183
are then connected to each other by radially extending portions 185. This
results in
a circular crenellated shape. The term "crenellated" as used herein does not
require
the inner arcuate portions, outer arcuate portions, and radially extending
portions to
be straight lines, but instead refers to the general up-and-down or in-and-out
shape
of the trailing edge. This crenellated structure forms two sets of mixing
lobes, high
energy mixing lobes 117 and low energy mixing lobes 119. Also shown in FIG. 7
is
the leading edge (not visible) of the turbine shroud, indicated here as dotted
circle
194, has a front radius of curvature 199. The front radius of curvature 199
can be
greater than, substantially equal to, or less than the outer radius of
curvature 195.
[0091] Referring now to FIG. 3, free stream fluid (indicated generally by
arrow
160, and which may be, for example, air or water) passing through the stator
142
has its energy extracted by the rotor 146. High energy fluid indicated by
arrow 162
bypasses the turbine shroud 110 and stator 142, flows over the exterior of the
turbine shroud 110, and is directed inwardly by the high energy mixing lobes
117.
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The low energy mixing lobes 119 cause the low energy fluid exiting downstream
from the rotor 146 to be mixed with the high energy fluid 162.
[0092] Referring now to FIG. 5, a tangent line 171 is drawn along the interior
trailing edge indicated generally at 172 of the high energy mixing lobe 117. A
rear
plane 173 of the turbine shroud 110 is present. A line 174 is formed normal to
the
rear plane 173 and tangent to the point 175 where a low energy mixing lobe 119
and
a high energy mixing lobe 117 meet. An angle 02 is formed by the intersection
of
tangent line 171 and line 174. This angle 02 is between 5 and 65 degrees. Put
another way, a high energy mixing lobe 117 forms an angle 02 between 5 and 65
degrees relative to a longitudinal axis of the turbine shroud 110. In
particular
embodiments, the angle 02 is from about 35 to about 50 .
[0093] In FIG. 7, a tangent line 176 is drawn along the interior trailing edge
indicated generally at 177 of the low energy mixing lobe 119. An angle 0 is
formed
by the intersection of tangent line 176 and line 174. This angle 0 is between
5 and
65 degrees. Put another way, a low energy mixing lobe 119 forms an angle 0
between 5 and 65 degrees relative to a longitudinal axis of the turbine shroud
110.
In particular embodiments, the angle 0 is from about 35 to about 50 .
[0094] Mixing lobes may be present on the turbine shroud. As shown in FIG. 2,
the ejector shroud 120 has a ring airfoil shape and does not have mixing
lobes. If
desired, though, mixing lobes may also be formed on a trailing edge 128 of the
ejector shroud.
[0095] In one aspect of the present disclosure, stators comprising moveable
components or members are disclosed. Three types of stators are considered. In
the first type, the stator vane is made of a stationary member and one or more
moveable members that extend longitudinally along the length of the stator hub
(i.e.
in line with the turbine shroud), which allow the camber of the stator vane to
be
changed. In the second type, the stator vane comprises a base (i.e. stationary
member) and a flap (i.e. moveable member) which opens outwardly from the base.
In the third type, the middle or central portion of the stator vane is made
from two
surface segments. By changing the exposed lengths of the central surface
segments, the camber of the stator vane can be changed. The stators disclosed
herein can be used to control the load experienced by the impeller of the
fluid turbine
containing the stator. The moveable component is moved between a first
position
and a second position to control the load.
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[0096] FIG. 8 is a front view of a stator of the present disclosure. FIG. 9 is
a top
view of the stator of FIG. 8, looking down into the side of one stator vane,
upwind
surface of a second stator vane, and the downwind surface of a third stator
vane.
The stator 200 comprises a stator hub 210 and stator vanes 220 extending
radially
from the stator hub. The stator hub 210 shown here is formed from a
cylindrical
sidewall 212 surrounding and defining a central passageway 214. Embodiments
are
also contemplated where the stator hub is formed from a sidewall and does not
have
a central passageway. As shown here, the vanes 220 are evenly spaced about the
stator hub sidewall 212. In particular embodiments, the stator 200 has nine
stator
vanes 220.
[0097] Each stator vane has a root 222 and a tip 224 at opposite ends of the
vane, with a vane length 226 (see FIG. 9) extending from the root to the tip.
The
vane may have an airfoil shape, or the vane may be symmetrical, as will be
further
described herein. The stator 200 also has a central longitudinal axis 205 (see
FIG.
9), corresponding to the horizontal axis of the shrouded fluid turbine (see
reference
numeral 105 in FIG. 1).
[0098] One example embodiment of a stator of the first type is shown in FIGS.
9-
12. Initially, arrow 201 indicates the direction of incoming fluid into the
stator. Here,
each stator vane 220 is formed from a stationary member 240 (i.e. base) and a
first
moveable member 260 (i.e. flap). The stationary member 240 and the first
moveable
member 260 are located longitudinally to each other along the stator hub 210.
As
depicted here, the stationary base is upstream of the first moveable member,
so that
the front end 246 of the stationary base 240 defines the leading edge 228 of
the
stator vane. The stationary base 240 also has a back end 248 opposite the
front end
246. The moveable member 260 is downstream of the stationary member 240. In
this embodiment, the moveable flap 260 defines the trailing edge 230 of the
stator
vane, and the stationary member does not define any part of the trailing edge.
The
stationary base 240 has a root end 242 and a tip end 244, corresponding to the
root
222 and the tip 224 of the stator vane. The moveable flap 260 also has a root
end
262 and a tip end 264, also corresponding to the root 222 and the tip 224 of
the
stator vane. The trailing edge 230 of the stator vane 220 is located on a back
end
268 of the moveable flap 260. The moveable flap 260 also has a front end 266
opposite the back end 268. The root end 242 of the stationary base 240 is
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connected to the stator hub 210. The root end 262 of the moveable flap 260 is
not
connected to the stator hub 210.
[0099] The back end 248 of the stationary base and the front end 266 of the
moveable flap are pivotally engaged by a connector 280. The connector 280
defines
a radial rotational axis 285, or in other words the radial axis 285 is normal
to the
stator hub 210, which is in the axial direction defined by central
longitudinal axis 205.
The moveable flap 260 can pivot or rotate relative to the stationary member
about
this radial axis 285, to change the shape of the stator vane 210 and change
the
incidence of fluid on the rotor blades downstream of the stator. Generally
speaking,
the back end 248 of the stationary base and the front end 266 of the moveable
flap
are shaped to join the base 240 and the flap 260 together, and to allow the
flap 260
to pivot relative to the stationary base 240.
[0100] The root end 242 of each stator vane stationary member 240 has a pitch
angle 8 where the stationary member 240 connects to the stator hub sidewall
212.
This root pitch angle is measured between the central longitudinal axis 205
and the
chord 252 of the stationary base 240 at the root. This example stator has a
non-zero
pitch angle 0, which is measured from the leading edge 228 of the stator, and
as a
result 0 cannot exceed 90 degrees. In embodiments, 0 is from greater than 0 to
less
than 90 degrees. In other embodiments, 0 is from 5 to 30 degrees, or from 15
to 45
degrees, or from 30 to 70 degrees.
[0101] The stationary member 240 (base) has a length 252 between the root end
242 and the tip end 244. The moveable member 260 (flap) also has a length 272
between the root end 262 and the tip end 264. In embodiments, the length 252
of
the stationary base and the length 272 of the moveable flap are equal.
[0102] It should be noted that as depicted here, the leading edge 228 of the
stator
vane is formed from the stationary member 240, while the trailing edge 230 is
formed
from the moveable member 260. It is also possible that the leading edge 228 of
the
stator vane is formed from the moveable member 260, while the trailing edge
230 is
formed from the stationary member 240. Thus, the stationary member 240 will
define either the leading edge or the trailing edge, but will not define both
edges at
the same time. It should also be noted that with respect to the members making
up
the stator vane, the terms "front end" and "back end" are intended to denote
opposite
ends of the member, and should not be construed as defining the position of a
given
end of the member relative to the other components of the fluid turbine.
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[0103] Referring now to FIG. 10, each stator vane 220 has a constant chord 232
and cross-section along the length 226 of the vane. Put another way, the vane
has a
constant pitch angle 0 along the length 226 of the vane. In addition, each
stationary
base 240 has a constant chord 250 and each moveable flap 260 has a constant
chord 270. In embodiments, the chord 250 of the stationary base is greater
than the
chord 270 of the moveable flap. It should be noted that the chord 232 of the
stator
vane is measured when the chord 250 of the stationary base and the chord 270
of
the moveable flap are parallel to each other.
[0104] In FIG. 11, the stator vane 320 is shown here with a symmetrical shape.
The moveable member 360 is at a positive flap angle. The flap angle is
positive
when the flap 360 is oriented in the direction of the upper surface 354 of the
stationary member 340, and is negative when the flap is oriented in the
direction of
the lower surface 356 of the stationary member 340. The flap angle OF is
measured
between the stationary member chord 350 and the moveable member chord 370 at
the rotational axis 385.
[0105] FIG. 10 and FIG. 11 illustrate the ability of the moveable member
260/360
to rotate about the rotational axis 285/385 of the connector 280/380, or in
other
words to move relative to the stationary member 240/340. In embodiments, the
stator vane flap 260/360 can rotate for an angle OF from minus 25 degrees to
plus 25
degrees, the angle being formed between the chord 250/350 of the stationary
member and the chord 260/360 of the moveable member at the rotational axis
formed by connector 280. in FIG. 10, the flap 260 is at an angle of 0 . These
two
figures also illustrate a first position and a second position in which the
moveable
component, i.e. the stator vane, can be moved to control the load experienced
by the
stator/rotor assembly of the fluid turbine.
[0106] Referring to FIG. 9 and FIG. 10, the aspect ratio is the ratio of the
length
226 of the stator vane divided by the chord (i.e. breadth) 232 of the stator
vane 220.
In this embodiment, the chord 232 is constant along the length 226 of the
stator
vane. However, if the chord 232 varies along the length 226 of the vane, the
aspect
ratio is determined as the ratio of the length squared divided by the area of
the stator
vane (i.e. including both the stationary base 240 and the moveable flap 260)
when
viewed from the top (i.e. the planform of the vane), like the view of FIG. 9.
In
embodiments, the stator vane 220 has an aspect ratio of from 2 to 30,
including from
to 25.
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[0107] All of the stator vane flaps 260 may be set at the same flap angle at
any
given time. In some embodiments, the stator 200 comprises a single mechanism
for
rotating the stator vane flaps 260. In other embodiments, each stator vane
flap can
be independently controlled. It is contemplated that the control mechanism is
an
active one.
[0108] In some versions or embodiments, the control mechanism is sensitive to
incident fluid flow properties. Put another way, fluid flow factors such as
incident
fluid velocity, pressure and temperature are associated with different
rotations of the
flaps about their rotational axis. Turbine geometry is generally highly
dependent on
an operational range defined by preselected flow characteristics. For example,
by
increasing the flap angle in response to an increase in incident flow
velocity, the
turbine can maintain high efficiency beyond typical off-design thresholds.
[0109] In the stators of the present disclosure, the rotation of the moveable
member 260 modifies the exit angle of the stator vane 220 independent of the
angle
of attack. A higher exit angle is required to efficiently direct a high
velocity flow onto
a rotor, but a high angle attack in a high velocity flow can cause flow
separation and
other efficiency losses. The addition of the moveable member allows the stator
to
maintain a low angle of attack while having a freely adjustable exit angle. In
other
words, the angle of attack on the leading edge 228 is not modified, just the
exit angle
on the trailing edge 230 of the stator vane flap.
[0110] FIG. 12 is a graph showing the values calculated by computational fluid
dynamics (CFD) for the percentage of the power generated by the rotor when
plotted
as a function of the stator flap angle in degrees. The fluid stream in this
calculation
was in an axial direction. A linear relationship is noted and the line y =
2.224X +
45.968 is fitted to the values. It is seen that the rotor generated its
maximum power
at a stator flap angle of 25 . In contrast, a stator flap angle of less than -
20 actually
caused power to be expended rather than produced.
[0111] The embodiment of FIGS. 9-12 contains a stationary member and one
moveable member. This design can be generalized to include a stationary member
and a plurality of moveable members. The stator vane comprises the stationary
member and a plurality of moveable members. The stationary member and the
moveable members are arranged longitudinally in a row along the stator hub.
The
front end of each member is pivotally engaged to the back end of an upstream
member. The stationary member can be located in any position in the row.
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[0112] FIGS. 13-15 illustrate an example of this design, where the stator vane
310 has a total of four segments or members that make up the cross section of
an
airfoil. The stator vane comprises an outer cover 320 that covers a set of
pivotally
engaged members that make up the airfoil. The outer cover provides a
relatively
smooth surface for the air to flow over the airfoil cross section of the
stator vane.
The outer surface is shown separated from the segments.
[0113] Here, the stator vane is shown with the front end 332 of stationary
member
330 defining the leading edge 312 of the stator vane. The back end 334 of the
stationary member is pivotally engaged with a front end 342 of a first
moveable
member 340. The back end 344 of the first moveable member is pivotally engaged
with a front end 352 of a second moveable member 350. The back end 354 of the
second moveable member is pivotally engaged with a front end 362 of a third
moveable member 360. The back end 364 of the third moveable member defines
the trailing edge 314 of the stator vane. In this embodiment, the stationary
member
330 does not make up any part of the trailing edge 314 of the airfoil shape of
the
stator vane. Similarly, none of the moveable members make up any part of the
leading edge 312 of the airfoil shape of the stator vane. Although four
segments are
shown, the stator vane may be comprised of more or fewer segments.
[0114] FIG. 15 is a magnified view showing the stator vane mounted on a
nacelle
308 of a wind turbine 300 with the moveable members configured for high
camber.
The rotor 306 is visible downstream of the stator. The outer cover is not
shown for
illustration purposes. A root end or distal end of the stationary member 330
is fixedly
attached to the nacelle 308. A tip end or proximal end of the stationary
member may
also be fixedly attached to the turbine shroud (not shown). The nacelle may
include
a short riser 316 above its surface to which the stator vane is mounted. The
first
moveable member 340, second moveable member 350, and third moveable member
360 follow downstream of the stationary member 330.
[0115] As shown here, the stationary member 330 defines the leading edge 312
of the stator vane and does not define any part of the trailing edge 314 of
the stator
vane. In some other embodiments, the stationary member 330 defines the
trailing
edge 314 of the stator vane and does not define any part of the leading edge
312 of
the stator vane. In still other embodiments, a first moveable member defines
the
leading edge 312, a second moveable member defines the trailing edge 314, and
the
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stationary member 330 is located in the row between the first and second
moveable
members.
[0116] FIGS. 16-28 illustrate various example embodiments of stators of the
second type, in which the stator vane comprises a stationary member (i.e. a
base)
and a moveable member (i.e. a flap) which opens outwardly from the base. In
these
embodiments, the stationary member defines both the leading edge and the
trailing
edge of the stator vane. The moveable member forms a portion of an upwind or
downwind surface of the stator vane. When opened or deployed, the moveable
member is deployed downstream of the trailing edge of the stationary member.
The
deployment can occur in at least two ways: by rotation of the moveable member
about a radial axis, or by extension of the moveable member longitudinally
from the
trailing edge of the stationary member.
[0117] FIG. 16 shows a wind turbine 400 and FIG. 17 shows a magnified view of
a stator vane 410. The stator vane comprises a stationary member 420 (i.e.
base)
and a first moveable member 430 (i.e. flap). The stationary member 420 defines
the
leading edge 412 and the trailing edge 414 of the stator vane. The stationary
member 420 also has a trailing edge 424 along the trailing edge 414 of the
stator
vane. The first moveable member 430 is located adjacent the trailing edge 414
of
the stator vane and forms a portion of the upwind surface 416 of the stator
vane. Put
another way, the first moveable member is located in the upwind surface. The
rotor
406 is visible downstream of the stator vanes 410. In this figure, the first
moveable
member is in a closed or stowed state, i.e. a first position. Here, the flap
430 has a
generally rectangular shape. The distal side surface 432 and the proximal side
surface 434 of the flap are of equal lengths when measured from the trailing
edge.
[0118] FIG. 19 shows the first moveable member in an open or deployed state,
i.e. a second position. In this figure, the stationary member 420 and the
first
moveable member 430 are pivotally engaged along a radial axis 405 which is
located along the trailing edge 424 of the stationary member 420. The flap
rotates
about this axis 405 to be deployed downstream of the trailing edge 414; this
rotation
is indicated by arrow 409. An interior surface 436 of the flap, which was
previously
hidden, now becomes an upwind surface. A pocket or recess 421 in the upwind
surface 416, in which the flap 430 rests when stowed, is now exposed. The
trailing
edge 438 of the flap 430 is further downstream than the trailing edge 424 of
the
stationary member.
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[0119] FIG. 21 also shows the first moveable member 430 in an open or deployed
state. However, this embodiment differs from that of FIG. 19 in the mechanism
by
which deployment occurs. Here, the first moveable member 430 extends
longitudinally from the trailing edge 424 of the stationary member. This can
be done,
for example, when the first moveable member 430 is connected to the stationary
member 420 along distal side surface 432 and proximal side surface 434. In
this
embodiment, the interior surface of the flap becomes a downwind surface (not
visible). The extension is represented via arrow 411.
[0120] FIG. 23 shows a further variation. Here, the trailing edge 438 formed
by
the flap 430 upon deployment has a nonlinear shape. For example, as
illustrated
here, the trailing edge has a sawtooth shape. Other nonlinear shapes which are
contemplated include a sinusoidal shape and a crenellated shape. Put another
way,
the flap comprises a nonlinear edge. FIG. 23 also shows the flap 430 deploying
via
extension rather than rotation, as indicated by the straight edge 427 (which
would
otherwise have a nonlinear shape that complements the shape of trailing edge
438).
[0121] FIG. 25 shows another variation. Here, an array or plurality of fluid
passages 450 is present between an upper surface 452 and a lower surface (not
visible) of the flap. This allows air to flow through the flap. The fluid
passages 450
may generally be of any shape, though here they are shown as circular
apertures.
[0122] In FIG. 27, a further variation is illustrated wherein the flap 430 has
an
asymmetrical shape along a radial length of the stator vane. This is reflected
in the
distal side surface 432 and the proximal side surface 434 of the flap having
different
lengths when measured from the trailing edge 414 of the stationary member 420
to
the trailing edge 438 of the flap 430. In the embodiment depicted, the distal
side
surface has a shorter length than the proximal side surface. However, the
opposite
may also be true.
[0123] The variations shown in FIGS. 22-27 (sawtooth edge, fluid passages,
asymmetrical shape) may also be combined as desired. In addition, these
embodiments depict a stator vane with a single moveable member or flap. It is
contemplated that a single stator vane may also include a plurality of such
moveable
flaps, and/or that each stator vane on a stator may have moveable flaps. Each
moveable flap may be independently controlled in those embodiments.
[0124] FIG. 28 is a front view of the wind turbine 400 wherein some the stator
vanes 410 have deployed flaps 430. Deployment of the flaps changes the flow of
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fluid incident to the rotor blades, providing additional control of the rotor
speed to
keep the power generator within its cut in/cut out range. It is contemplated
that the
flaps on the stator vanes of the stator can be controlled independently to
provide
finer control over the fluid flow. As shown here, there are nine stator vanes,
with four
having flaps deployed and five having flaps stowed (reference numeral 431).
Put
another way, some of the stator vanes are in a first position and some of the
stator
vanes are in a second position that allow for control of the load experienced
by the
impeller on the fluid turbine.
[0125] FIG. 29 and FIG. 30 show another example embodiment of the stator
vane. Again, the stationary member 420 defines both the leading edge 412 and
the
trailing edge 414 of the stator vane 410. Here, however, the moveable
member(s)
rotate(s) about a radial axis that is located in a central portion 423 of the
stationary
member. This embodiment shows two moveable members or flaps; however,
embodiments with one or more flaps are also contemplated. The first moveable
member 430 forms a portion of the upwind surface 416 of the stator vane. The
second moveable member 460 forms a portion of the downwind surface 418 of the
stator vane. Here, the moveable members are shown in a deployed state. The
radial axis 435, 465 of each moveable member is located in a central portion
423 of
the stationary member. The moveable members (i.e. flaps) are shown as
extending
along the entire radial length of the stator vane; however, variations are
also
contemplated where the flap extends along a portion of the radial length (i.e.
not
along the entire radial length). Arrows 407 depict the direction of wind
travel around
the stator vane 410 and rotor blade 406.
[0126] FIGS. 33-42 illustrate various embodiments of stators of the third
type. In
these stator vanes, the middle or central portion of the stator vane is made
from two
surface segments. By changing the exposed lengths of the central surface
segments, the camber of the stator vane can be changed.
[0127] A side view of one example embodiment is seen in FIGS. 31-34. Here,
the stator vane 510 comprises a leading edge member 520, an upper surface
segment 530, a lower surface segment 540, and a trailing edge member 550. The
leading edge member 520 defines the leading edge 512 of the stator vane at a
front
end 522. The leading edge member 520 includes an upper surface 526 and a lower
surface 528 along a back end 524. The upper surface 526 of the leading edge
member is longitudinally engaged with the forward edge 532 of the upper
surface
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segment 530. The lower surface 528 of the leading edge member is
longitudinally
engaged with the forward edge 542 of the lower surface segment 540. More
generally, the back end 524 of the leading edge member is longitudinally
engaged
with the forward edges 532, 542 of the upper and lower surface segments. The
trailing edge member 550 defines the trailing edge 514 of the stator vane at a
rear
end 554. The trailing edge member includes an upper surface 556 and a lower
surface 558 along a front end 552. The upper surface 556 of the trailing edge
member is longitudinally engaged with the rear edge 534 of the upper surface
segment. The lower surface 558 of the trailing edge member is longitudinally
engaged with the rear edge 544 of the lower surface segment. More generally,
the
front end 552 of the trailing edge member is longitudinally engaged with the
rear
edges 534, 544 of the upper and lower surface segments. Either the leading
edge
member 520 or the trailing edge member 550 is stationary, i.e. attached to the
stator
hub.
[0128] The upper surface segment 530 and the lower surface segment 540 move
longitudinally relative to the leading edge member 520 and the trailing edge
member
550 to change the camber of the stator vane. Put another way, the exposed
surface
area of the upper surface segment and the lower surface segment change as the
camber is changed. The stator vane of FIG. 31 has a positive camber. The
stator
vane of FIG. 33 has zero camber. The stator vane of FIG. 34 has a negative
camber.
[0129] FIG. 35 and FIG. 36 illustrate some components that drive the
longitudinal
lateral motion and engagement of the various moving parts. Lateral motion
guides
560 comprise slots and pins, with a plurality of slots in one surface and a
plurality of
pins in the mating surface, such that the components are able to move
longitudinally
with respect to one another while remaining engaged. One method of moving the
upper and lower surface segments 530, 540 is shown wherein a pair of linear
motion
actuators 562 is housed in one of the edge members, here the leading edge
member
520. Cables 564 extend from the linear motion actuators 562 to the upper and
lower
surfaces of the other edge member, i.e. upper and lower surfaces 556, 558 of
the
trailing edge member 550. Generally, the cables have the same length. Thus,
when
for example the cable leading to the lower surface 558 is shortened and the
cable
leading to the upper surface 556 is lengthened, the change in lengths will
cause the
exposed surface area of upper surface segment 530 to increase and cause the
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exposed surface area of lower surface segment 540 to decrease. These change in
lengths change the camber, thus impacting the airfoil shape of the stator
vane. It is
also contemplated that the linear motion actuators 562 are housed in the
trailing
edge member 550, and that the cables 564 extend to the upper and lower
surfaces
526, 528 of the leading edge member 520.
[0130] In FIG. 35 and FIG. 36, the stator vane 510 is shown in three different
positions. Two positions (positive, neutral) configurations are shown in
dotted lines.
The negative camber configuration is shown in solid lines. Again, the moveable
component (i.e. the stator vane) can be moved between two different positions
to
control the load experienced by the impeller incorporating this stator vane.
[0131] FIG. 37 and FIG. 38 illustrate another method of actuating motion
between
the various components. Here, a drive pulley 566 is located within one of the
edge
members, here the leading edge member 520. A single cable 564 engages the
drive
pulley. Each end of the cable 564 is attached to a fixed point on the other
edge
member, i.e. trailing edge member 550, the fixed point being shown here as
single
point 568 (although the ends can be attached to separate fixed points if
desired).
The distance between the drive pulley and the fixed point(s) 568 is constant,
or fixed.
The upper surface segment 530 and the lower surface segment 540 engage the
cable 564 on opposite sides of the drive pulley 566. As the drive pulley is
rotated
either clockwise or counter-clockwise, one side is shortened while the
opposite side
is lengthened, thus causing the upper and lower surface segments to move and
shorten / lengthen the surfaces of the airfoil shape.
[0132] Another method is illustrated in FIG. 39. A first linear motion
actuator 570
is axially engaged and pivotally engaged with a fixed point 572 along the
upper
surface 526 of the leading edge member 520, and also axially engaged and
pivotally
engaged with a fixed point 574 along the upper surface 556 of the trailing
edge
member 550. A second linear motion actuator 580 is axially engaged and
pivotally
engaged with a fixed point 582 along the lower surface 528 of the leading edge
member 520, and also axially engaged and pivotally engaged with a fixed point
584
along the lower surface 558 of the trailing edge member 550. As depicted here,
fixed points 574 and 584 are the same point, though of course they can be
separate
points. Telescoping linear motion actuators are common and may employ screw
drive, pneumatics, or other means to cause elongation. By lengthening one
actuator
while shortening the opposite actuator, the airfoil camber may be changed as
the
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leading edge member 520 and trailing edge member 550 move relative to upper
surface segment 530 and lower surface segment 540.
[0133] Another method is illustrated in FIG. 40. Linear motion actuator 590
connects upper surface 526 of the leading edge member 520 with the forward
edge
532 of upper surface segment 530. Linear motion actuator 592 connects lower
surface 528 of the leading edge member 520 with the forward edge 542 of lower
surface segment 540. Linear motion actuator 594 connects upper surface 556 of
the
trailing edge member 550 with the rear edge 534 of upper surface segment 530.
Linear motion actuator 596 connects lower surface 558 of the trailing edge
member
550 with the rear edge 544 of lower surface segment 540. The upper and lower
surface segments 530, 540 are engaged to the leading and trailing edge members
520, 550, as previously described and can move relative to them. As the linear
actuators are lengthened or shortened, the airfoil camber is altered.
[0134] FIG. 41 and FIG. 42 show stator vanes of the third type in a positive
camber configuration on a wind turbine 500. The distal end of the leading edge
member 520 engages the nacelle 508 and the proximal end of the leading edge
member engages the turbine shroud 503. The upper surface segment 530 and
lower surface segment 540 can be seen on various stator vanes.
[0135] The various stator vanes depicted above can be moved between a first
position and a second position to control the load experienced by the fluid
turbine. It
is contemplated that the moveable component of these stator vanes can be moved
actively or passively. By "actively", it is contemplated that the moveable
component
receives an instruction from a controller, for example from a computer program
running instructions or from a user of the fluid turbine. By "passively," it
is
contemplated that the moveable component does not receive an instruction from
a
controller, but rather moves based on changes in ambient conditions. For
example,
it is contemplated that the moveable member 430 described in FIGS. 17-19 could
be
designed to passively open when the fluid velocity exceeds a given threshold
and
"blows" the moveable member out of the pocket 421.
[0136] In a further aspect of the present disclosure, rotors comprising
moveable
components are disclosed. The rotor blade is hollow. The upstream surface and
the
downstream surface of the rotor blade each contain a fluid passage. Located
within
the hollow rotor blade is a gate that opens and closes the fluid passages
depending
on the rotational speed of the rotor. This rotational speed is dependent upon
the
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CA 02796432 2012-10-12
WO 2011/140412 PCT/US2011/035460
fluid velocity. Above a given fluid velocity threshold, the gate opens the
fluid
passages to create an aperture through the rotor blade that the fluid can flow
through. Put another way, the rotor may contain a moveable component made up
of
a stationary member and a moveable member. The stationary member is the outer
rotor blade skin, which is hollow. The moveable member is the gate.
[0137] FIGS. 43-49 provide various views of one example embodiment. FIG. 43
is an exterior view of the overall rotor 600. FIG. 44 is a magnified view of
the hollow
outer rotor blade skin 610. Here, fluid passages 620 having the shape of
circular
apertures are seen in the upstream surface 612 of the rotor blade. However,
the
fluid passages may have any shape. Inserts 630 are seen inserted into the
fluid
passages 620 to prevent fluid flow through the rotor blade. FIG. 45 is a
magnified
view of the rotor blade skin 610 wherein the inserts have been removed so that
fluid
can flow through the fluid passages 620. The downstream surface 614 is visible
through the fluid passages.
[0138] FIGS. 47-49 show various interior views of the rotor blade skin 610. In
FIG. 47, the upstream surface 612 and the downstream surface 614 are shown.
Fluid passages 620 are present in both surfaces. Arrow 605 indicates a radial
axis.
The gate 640 that controls fluid flow is also visible. The gate 640 comprises
an
insert 630 for each fluid passage. The insert covers the fluid passage and
prevents
fluid flow through the fluid passage. It is contemplated that the insert may
have, for
example, a half-sphere, cylindrical, or circular cone shape.
[0139] As seen in FIG. 48 and FIG. 49, the insert(s) 630 is/are operatively
connected to a pivoting arm 642. For example, as seen in FIG. 49, the inserts
may
be mounted onto a plate 644 which is connected to a pivoting arm 642. It is
contemplated that there are two pivoting arms 642, one for the fluid
passage(s) on
the upstream surface 612 and one for the fluid passage(s) on the downstream
surface 614. The pivoting arms 642 engage a weighted member 650. The weighted
member 650 in turn engages a tension member 660. The tension member is
connected to the rotor at the distal end 602, or in other words at the center
of the
rotor, not the tip of the rotor blade. An example of a tension member is a
spring.
The tension member acts to bias the gate in the direction towards the center
of the
rotor.
[0140] FIG. 48 illustrates the rotor blade in a closed state, i.e. when the
inserts
630 are aligned with the fluid passages 620 of the rotor blade skin 610. In
this
CA 02796432 2012-10-12
WO 2011/140412 PCT/US2011/035460
illustration, the rotor is exposed to a fluid velocity which is below a given
threshold.
The tension in the tension member 660 is stronger than the rotational force,
and the
tension member thus maintains the bias of the gate 640 towards the distal end
602,
as indicated by arrow 619. The pivoting arms 642 are biased away from the
weighted member 650 and towards the rotor blade surfaces 612, 614. Below the
fluid velocity threshold, there may be some "give" in the pivoting arms 642 so
that
although the tension member and weighted member may move relative to the
distal
end 602, the inserts 630 remain aligned with the fluid passages 620.
[0141] FIG. 49 illustrates the rotor blade in an open state. In this
illustration, the
rotor is exposed to a fluid velocity above the given threshold. This generates
a force
(indicated by arrow 615) that causes the weighted member 650 to move away from
the distal end 602, overcomes the bias towards the center of the rotor, and
causes
the tension member 660 to move or stretch such that the pivoting arms 642 can
no
longer travel. This causes the plate 644 and the inserts 630 mounted thereon
to be
removed from the fluid passages 620. Fluid can consequently flow through the
fluid
passages 620. This will cause the rotational speed of the rotor to decrease,
reducing the load on the rotor in high fluid velocity conditions. These
figures
illustrate an embodiment wherein the moveable member of the rotor blade, i.e.
the
gate, moves passively in response to an increased rotor speed which can occur
when the ambient conditions change, e.g. when the fluid velocity increases
relative
to its prior speed.
[0142] The stators, rotors, and shrouds of the present disclosure can be made
using materials and methods known in the art.
[0143] The present disclosure has been described with reference to several
different embodiments. Modifications and alterations will occur to others upon
reading and understanding the preceding detailed description. It is intended
that the
present disclosure be construed as including all such modifications and
alterations
insofar as they come within the scope of the appended claims or the
equivalents
thereof.
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