Note: Descriptions are shown in the official language in which they were submitted.
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FLUID TURBINES
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application
Ser. No. 61/415,626, filed Nov. 19, 2010, and U.S. Patent Application Serial
No.
13/078,382, filed Apr. 1, 2011. This application relates to U.S. Patent
Application
Ser. No. 12/054,050, filed Mar. 24, 2008, and U.S. Provisional Patent
Application Ser. No. 60/919,588, filed Mar. 23, 2007. The disclosures of these
applications are hereby fully incorporated by reference in their entirety.
FIELD OF INVENTION
[0002] The present disclosure relates to shrouded fluid turbines having
various configurations.
BACKGROUND
[0003] 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. HAWTs will not exceed the Betz limit of 59.3% efficiency in
capturing
the potential energy of the wind passing through it. HAWTs are also heavy,
requiring substantial support and increasing transport costs of the
components.
It would be desirable to increase the efficiency of a fluid turbine by
collecting
additional energy from the fluid.
BRIEF DESCRIPTION
[0004] The present disclosure relates to shrouded fluid turbines of
various
configurations. The fluid turbines include an impeller, a turbine shroud, and
an
ejector shroud in various configurations. In some configurations, a plurality
of
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fluid ducts is used in lieu of an ejector shroud. In others, an external
stator
extends radially from the ejector shroud.
[0005] The fluid turbines may be used as, for example, wind turbines or
water turbines.
[0006] Disclosed in embodiments is a fluid turbine comprising: an
impeller; a
turbine shroud surrounding the impeller, the turbine shroud comprising a
leading
edge and a plurality of mixing lobes that form a crenellated trailing edge;
and an
ejector shroud completely surrounding the turbine shroud, the ejector shroud
comprising a leading edge and a trailing edge.
[0007] In some embodiments, the leading edge of the turbine shroud is
coplanar with the leading edge of the ejector shroud. In others, the leading
edge
of the turbine shroud is downstream of the leading edge of the ejector shroud.
[0008] In particular versions, the leading edge of the turbine shroud has
a
substantially circular shape. In others, the leading edge of the ejector
shroud
has a substantially circular shape. The ejector shroud may have a ring airfoil
shape.
[0009] The fluid turbine may further comprise a nacelle body, the
impeller
surrounding the nacelle body, the nacelle body having a trailing edge, wherein
the nacelle body, turbine shroud, and ejector shroud are coaxial to each
other.
The trailing edge of the nacelle body can be upstream or downstream of the
trailing edge of the ejector shroud.
[0010] The impeller may be a rotor/stator assembly.
[0011] Also disclosed is a fluid turbine comprising: an impeller; a
turbine
shroud surrounding the impeller, the turbine shroud comprising a plurality of
open slots downstream of the impeller; and an exterior structure for directing
fluid flow from outside the turbine shroud through the plurality of open
slots.
[0012] In some embodiments, the exterior structure for directing fluid
flow is
an ejector shroud disposed about the turbine shroud, the turbine shroud and
the
ejector shroud being sealed to each other downstream of the plurality of open
slots.
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[0013] In other embodiments, the exterior structure for directing fluid
flow is a
plurality of fluid ducts located along an exterior surface of the turbine
shroud,
each fluid duct comprising an inlet and an outlet, the outlet being connected
to
one of the opens slot in the turbine shroud.
[0014] Each fluid duct may further comprise a fluid duct impeller.
[0015] The inlets of the plurality of fluid ducts are downstream of an
inlet end
of the turbine shroud and are parallel to the inlet end of the turbine shroud.
[0016] Also disclosed is a fluid turbine comprising: an impeller; a
turbine
shroud surrounding the impeller; an ejector shroud downstream of the turbine
shroud, a trailing edge of the turbine shroud extending into an inlet end of
the
ejector shroud; and a stator connected to an exterior surface of the ejector
shroud.
[0017] In embodiments, the turbine shroud comprises a substantially
circular
leading edge and a plurality of mixing lobes that form a crenellated trailing
edge.
[0018] The stator may have a ring airfoil shape. The ejector shroud may
have
a ring airfoil shape.
[0019] These and other non-limiting features or characteristics of the
present
disclosure will be further described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] 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.
[0021] FIG. 1 is a front left perspective view of a shrouded fluid
turbine.
[0022] FIG. 2 is a rear right perspective view of the shrouded fluid
turbine of
FIG. 1.
[0023] FIG. 3 is a front perspective view of a first exemplary shrouded
fluid
turbine.
[0024] FIG. 4 is a first right side perspective cross-sectional view of
the fluid
turbine of FIG. 3.
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[0025] FIG. 5 is a second right side perspective cross-sectional view of
the
fluid turbine of FIG. 3.
[0026] FIG. 6 is a side cross-sectional view of the fluid turbine of FIG.
3.
[0027] FIG. 7 is a front perspective view of a second exemplary shrouded
fluid turbine.
[0028] FIG. 8 is a right side perspective cross-sectional view of the
fluid
turbine of FIG. 7.
[0029] FIG. 9 is a side cross-sectional view of the fluid turbine of FIG.
7.
[0030] FIG. 10 is a left front perspective view of a third exemplary
shrouded
fluid turbine.
[0031] FIG. 11 is a front view of the shrouded fluid turbine of FIG. 10.
[0032] FIG. 12 is a left cross-sectional view of the shrouded fluid
turbine of
FIG. 10.
[0033] FIG. 13 is a left front perspective view of a third exemplary
shrouded
fluid turbine, having fluid ducts.
[0034] FIG. 14 is a front view of the shrouded fluid turbine of FIG. 13.
[0035] FIG. 15 is a left cross-sectional view of the shrouded fluid
turbine of
FIG. 13. The nacelle body is removed so that aspects of the turbine shroud are
visible.
[0036] FIG. 16 is a left front perspective view of a third exemplary
shrouded
fluid turbine, having impellers in the fluid ducts.
[0037] FIG. 17 is a front view of the shrouded fluid turbine of FIG. 16.
[0038] FIG. 18 is a left cross-sectional view of the shrouded fluid
turbine of
FIG. 16. The nacelle body is removed so that aspects of the turbine shroud are
visible.
[0039] FIG. 19 is a perspective view of a shrouded fluid turbine with an
external stator
[0040] FIG. 20 is a cross-sectional view of the shrouded fluid turbine of
FIG.
2
[0041] FIG. 21 is a smaller view of FIG. 20
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[0042] FIG. 21A and FIG. 21B are magnified views of the mixing lobes of
the
fluid turbine of FIG. 21.
[0043] FIG. 22 is a rear view of the shrouded fluid turbine of FIG. 2.
The
impeller is removed from this figure so that other aspects of the fluid
turbine can
be more clearly seen and explained.
DETAILED DESCRIPTION
[0044] 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 exemplary embodiments.
[0045] Although specific terms are used in the following description,
these
terms are intended to refer only to particular structures in the drawings and
are
not intended to limit the scope of the present disclosure. It is to be
understood
that like numeric designations refer to components of like function.
[0046] 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."
[0047] A Mixer-Ejector Power System (MEPS) provides an improved means
of generating power from wind currents. A primary shroud contains an impeller
which extracts power from a primary wind stream. A mixer-ejector pump is
included that ingests flow from the primary wind stream and secondary flow,
and
promotes turbulent mixing. This enhances the power system by increasing the
amount of air flow through the system, reducing back pressure on turbine
blades, and reducing noise propagating from the system.
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[0048] The term "impeller" is used herein to refer to any assembly in
which
blades are attached to a shaft and able to rotate, allowing for the generation
of
power or energy from fluid rotating the blades. Exemplary 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.
[0049] The end of the fluid turbine wherein fluid enters to rotate the
impeller
may be considered the front of the fluid turbine, and the end of the fluid
turbine
where fluid exits after passing through the impeller 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.
[0050] The present disclosure relates to different configurations of a
shrouded fluid turbine. The fluid turbines may be used as a wind turbine or a
water turbine. FIG. 1 and FIG. 2 initially present some details of the
shrouded
fluid turbine which will help in discussing various aspects of the different
configurations.
[0051] 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. Support
members 106 connect the turbine shroud 110 to the ejector shroud 120. The
impeller 140 surrounds the nacelle body 150. The nacelle body 150 is
connected to the turbine shroud 110 through the impeller 140, or by other
means.
[0052] 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 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 116. 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
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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.
[0053] A mixer-ejector pump (indicated by reference numeral 101)
comprises
an ejector shroud 120 surrounding the ring of mixing lobes 116 on the turbine
shroud 110. The mixing lobes 116 extend downstream and into an inlet end 122
of the ejector shroud 120. This mixer/ejector pump provides the means for
consistently exceeding the Betz limit for operational efficiency of the fluid
turbine.
[0054] In additional embodiments of the present disclosure, the ejector
shroud completely surrounds the turbine shroud. Generally, the turbine shroud
is
located between the leading and trailing edges of the ejector shroud.
[0055] FIGS. 3-6 are different views of one exemplary embodiment where
the
ejector shroud completely surrounds the turbine shroud. Here, the shrouded
fluid turbine 300 comprises an impeller 340 which surrounds a nacelle body
350.
The impeller is depicted here as a rotor/stator assembly. The nacelle body 350
has a trailing edge 352, which in this embodiment appears to be a tapered
point.
The impeller 340 is surrounded by turbine shroud 310. Ejector shroud 320 in
turn completely surrounds the turbine shroud 310. The leading edge 314 of the
turbine shroud 310 has a substantially circular shape. The leading edge 324 of
the ejector shroud 320 also has a substantially circular shape. The nacelle
body
350, impeller 340, turbine shroud 310, and ejector shroud 320 are coaxial with
each other, i.e. share a common axis.
[0056] As seen in FIG. 4 and FIG. 5, a plurality of mixing lobes 316 is
present
on the rear end of the turbine shroud, resulting in a crenellated trailing
edge 318.
[0057] As seen in FIG. 6, the turbine shroud has a leading edge 314 and a
trailing edge 318. Similarly, the ejector shroud has a leading edge 324 and a
trailing edge 328. The leading edge 314 of the turbine shroud is coplanar with
the leading edge 324 of the ejector shroud. In addition, the trailing edge 328
of
the ejector shroud is downstream of the trailing edge 318 of the turbine
shroud.
The trailing edge 318 of the turbine shroud is downstream of the impeller 340.
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The ejector shroud 320 has a ring airfoil shape, i.e. has the cross-sectional
shape of an airfoil with the suction side (i.e. low pressure side) on the
interior of
the ejector shroud.
[0058]
FIGS. 7-9 are different views of a second exemplary embodiment
where the ejector shroud completely surrounds the turbine shroud. Here, the
shrouded fluid turbine 400 comprises an impeller 440 which surrounds a nacelle
body 450. The impeller is depicted here as a rotor/stator assembly. The
nacelle
body 450 has a trailing edge 452, which in this embodiment appears to be a
tapered point. The impeller 440 is surrounded by turbine shroud 410. Ejector
shroud 420 in turn completely surrounds the turbine shroud 410. The leading
edge 414 of the turbine shroud 410 has a substantially circular shape. The
leading edge 424 of the ejector shroud 420 also has a substantially circular
shape. The nacelle body 450, impeller 440, turbine shroud 410, and ejector
shroud 420 are coaxial with each other, i.e. share a common axis.
[0059] As
seen in FIG. 8, a plurality of mixing lobes 416 is present on the
rear end of the turbine shroud, resulting in a crenellated trailing edge 418.
[0060] As
seen in FIG. 9, the turbine shroud has a leading edge 414 and a
trailing edge 418. Similarly, the ejector shroud has a leading edge 424 and a
trailing edge 428. The leading edge 414 of the turbine shroud is downstream of
the leading edge 424 of the ejector shroud. In addition, the trailing edge 428
of
the ejector shroud is downstream of the trailing edge 418 of the turbine
shroud.
The trailing edge 418 of the turbine shroud is downstream of the impeller 440.
The ejector shroud 420 has a ring airfoil shape, i.e. has the cross-sectional
shape of an airfoil with the suction side (i.e. low pressure side) on the
interior of
the ejector shroud.
[0061] It
should be noted that in FIG. 6, the trailing edge 352 of the nacelle
body 350 is upstream of the trailing edge 328 of the ejector shroud 320. In
FIG.
9, the trailing edge 452 of the nacelle body 450 is downstream of the trailing
edge 428 of the ejector shroud 420. The location of the trailing edge of the
nacelle body may vary
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[0062] In other additional embodiments of the present disclosure, the
fluid
turbine includes a turbine shroud that comprises a plurality of open slots
downstream of the impeller. An "open slot" allows fluid flowing along an
exterior
surface of the turbine shroud to pass radially from the exterior to the
interior of
the turbine shroud. The fluid turbine also includes an exterior structure
which
directs fluid flow from outside the turbine shroud through the plurality of
open
slots.
[0063] FIGS. 10-12 show different views of one exemplary embodiment of
such a fluid turbine. The shrouded fluid turbine 500 comprises an impeller 540
which surrounds a nacelle body 550. The impeller is depicted here as a
rotor/stator assembly. The nacelle body 550 has a trailing edge 552, which in
this embodiment appears to be a tapered point. The impeller 540 is surrounded
by turbine shroud 510. In this embodiment, ejector shroud 520 acts as the
exterior structure for directing fluid flow. The leading edge 514 of the
turbine
shroud 510 has a substantially circular shape. The leading edge 524 of the
ejector shroud 520 also has a substantially circular shape. The nacelle body
550, impeller 540, turbine shroud 510, and ejector shroud 520 are coaxial with
each other, i.e. share a common axis.
[0064] As seen in FIG. 12, the turbine shroud 510 has a ring airfoil
shape,
with the suction side on the interior of the turbine shroud. A plurality of
open
slots 560 are located downstream of impeller 540. The open slots here are
located along a trailing edge 504 of the fluid turbine. The turbine shroud 510
and
ejector shroud 520 are sealed to each other downstream of the open slots 560.
Put another way, the fluid turbine has only one trailing edge, rather than the
turbine shroud and ejector shroud having separate trailing edges, as seen for
example in the embodiment of FIG. 2. High energy fluid 568 flowing along an
exterior surface 517 of the turbine shroud 510 is directed by the ejector
shroud
520 through the open slots 560.
[0065] As drawn in FIG. 12, the leading edge 514 of the turbine shroud is
coplanar with the leading edge 524 of the ejector shroud. The leading edge 524
of the ejector shroud may be upstream of the leading edge 514 of the turbine
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shroud (see FIG. 9) or downstream of the leading edge of the turbine shroud
(see FIG. 1), as desired. Similarly, the open slots 560 are shown as being
located along the trailing edge 504 of the fluid turbine. This aspect is not
required. Rather, the open slots 560 must be located downstream of impeller
540.
[0066] FIGS. 13-15 show different views of another exemplary embodiment
of a fluid turbine with open slots. The shrouded fluid turbine 600 comprises
an
impeller 640 which surrounds a nacelle body 650. The impeller is depicted here
as a rotor/stator assembly. The impeller 640 is surrounded by turbine shroud
610. The leading edge 614 of the turbine shroud 610 has a substantially
circular
shape. The nacelle body 650, impeller 640, and turbine shroud 610 are coaxial
with each other, i.e. share a common axis.
[0067] As seen in FIG. 15, the turbine shroud 610 has a ring airfoil
shape,
with the suction side on the interior of the turbine shroud. A plurality of
open
slots 660 are located downstream of impeller 640. In contrast with the
embodiment of FIG. 12, the open slots 660 here are separated from the trailing
edge 604 of the turbine shroud. The open slots are seen here as having an
elliptical shape, although in principle any shape may be used.
[0068] A plurality of fluid ducts 670 is located along the exterior
surface 617
of the turbine shroud. Each fluid duct 670 comprises an inlet 672 and an
outlet
674. The outlet 674 of a fluid duct is connected to an open slot 660 in the
turbine
shroud. The inlet 672 is downstream of the inlet end 611 of the turbine
shroud,
and is parallel to the inlet end as well.
[0069] FIGS. 16-18 show different views of another exemplary embodiment
of a fluid turbine similar to that of FIGS. 13-15. This embodiment differs in
that
each fluid duct 670 has a fluid duct impeller 675. The fluid duct impeller 675
is
powered, so that fluid is forced into the exhaust stream of the turbine shroud
through the open slots 660.
[0070] FIG. 19 shows another configuration of a fluid turbine 800 similar
to
that of FIG. 1, but having an external stator. The shrouded fluid turbine 800
comprises an impeller 840 which surrounds a nacelle body 850. The impeller is
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depicted here as a rotor/stator assembly. Stator vanes 844 and rotor blades
848
are visible. The impeller 840 is surrounded by turbine shroud 810. The turbine
shroud has a plurality of mixing lobes 816 that form a crenellated trailing
edge
818. The leading edge 814 of the turbine shroud 810 has a substantially
circular
shape.
[0071] An ejector shroud 820 is downstream of the turbine shroud 810. The
mixing lobes 816 of the turbine shroud extend downstream and into an inlet end
822 of the ejector shroud 820. The leading edge 824 of the ejector shroud 820
also has a substantially circular shape. The nacelle body 850, impeller 840,
turbine shroud 810, and ejector shroud 820 are coaxial with each other, i.e.
share a common axis. The ejector shroud 820 has a ring airfoil shape, i.e. has
the cross-sectional shape of an airfoil with the suction side (i.e. low
pressure
side) on the interior of the ejector shroud.
[0072] A stator 880 is connected to an exterior surface 827 of the
ejector
shroud. The stator may also have a ring airfoil shape.
[0073] The turbine shroud and the ejector shroud may be formed to be
lightweight. For example, they can be formed by covering a rigid frame or
skeleton with a skin. The shrouds may comprise the same or different
materials.
The material for the shroud skins may include polymeric films. Exemplary
polymeric films include high density polyethylene (HDPE); polyesters such as
polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or
polytrimethylene terephthalate (PTT); and polyurethane films. Both aliphatic
and
aromatic polyurethane along with polyether and polyester polyols may be
utilized. Peroxide cured unsaturated polyester polymers in a glass matrix may
also be used. The glass may be E or S glass. A composite matrix may also
contain epoxy systems to improve the strength of the composite.
[0074] Other exemplary materials include polyvinyl chloride (PVC),
polyurethane, polyfluoropolymers, and multi-layer films of similar
composition.
Stretchable fabrics, such as spandex-type fabrics or polyurethane-polyurea
copolymer containing fabrics, may also be employed.
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[0075] Polyurethane films are tough and have good weatherability. The
polyester-type polyurethane films tend to be more sensitive to hydrophilic
degradation than polyether-type polyurethane films. Aliphatic versions of
these
polyurethane films are generally ultraviolet resistant as well.
[0076] Exemplary polyfluoropolymers include polyvinyldidene fluoride
(PVDF)
and polyvinyl fluoride (PVF). Commercial versions are available under the
trade
names KYNAR® and TEDLAR®. Polyfluoropolymers generally have
very low surface energy, which allow their surface to remain somewhat free of
dirt and debris, as well as shed ice more readily as compared to materials
having a higher surface energy.
[0077] The skin may be reinforced with a reinforcing material. Examples
of
reinforcing materials include but are not limited to highly crystalline
polyethylene
fibers, paramid fibers, and polyaramides.
[0078] The skin may independently be multi-layer, comprising one, two,
three, or more layers. Multi-layer constructions may add strength, water
resistance, UV stability, and other functionality. However, multi-layer
constructions may also be more expensive and add weight to the overall fluid
turbine.
[0079] Film/fabric composites are also contemplated along with a backing,
such as foam.
[0080] FIGS. 1-2 and FIGS. 20-22 illustrate various additional aspects of
the
different configurations of the shrouded fluid turbines of the present
disclosure.
Again, 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 downstream and "in-line"
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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
rotor blades are held together by an inner ring and an outer ring (not
visible),
and the rotor 146 is mounted on the nacelle body 150. The nacelle body 150 is
connected to the turbine shroud 110 through the stator 142, or by other means.
In some embodiments, a central passageway 152 may also extend through the
nacelle body 150.
[0082] 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.
[0083] 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.
Sound
absorbing material can affixed to the inner surface of the shrouds, and 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 will 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.
[0084] The area ratio of the ejector pump, as defined by the ejector
shroud
120 exit area over the turbine shroud 110 exit area, will be in the range of
1.5-
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3Ø The number of mixing lobes can be between 6 and 28. The height-to-width
ratio of the lobe channels will be between 0.5 and 4.5. The mixing lobe
penetration will be between 50% and 80%. The nacelle body 150 plug trailing
edge angles will be thirty degrees or less. The length to diameter (L/D) of
the
overall fluid turbine will be between 0.5 and 1.25.
[0085] Referring now to FIG. 22, the turbine shroud 110 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.
[0086] As seen in FIG. 2, the leading edge 112 of the turbine shroud 110
has
a substantially circular shape. As seen in FIG. 22, 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. Between portions are several
outer arcuate portions 183, which each have the same radius of curvature. The
radius of curvature for the inner arcuate portions 181 is different from the
radius
of curvature 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).
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.
[0087] The outer arcuate portions 183 are located in an outer plane,
which is
indicated here with reference numeral 190. The inner arcuate portions 181 are
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located in an inner plane indicated here with reference numeral 192. As seen
from this perspective, the outer plane 190 and inner plane 192 are generally
cylindrical, with their axis being the central axis 105. The outer plane 190
and
inner plane 192 are also coaxial.
[0088] The leading edge of the turbine shroud, indicated here as dotted
circle
194, has a front radius of curvature 199. The outer radius of curvature 195 of
the
outer arcuate portions is greater than the inner radius of curvature 197 for
the
inner arcuate portions. The front radius of curvature 199 of the leading edge
of
the turbine shroud can be greater than, substantially equal to, or less than
the
outer radius of curvature 195.
[0089] Referring now to FIG. 20, free stream fluid (indicated generally
by
arrow 160, which may be, for example, wind 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. 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.
[0090] Referring now to FIG. 21A, 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 171 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 . Put another way, a high energy mixing lobe 117 forms an angle 02
between 5 and 65 relative to a longitudinal axis of the turbine shroud 110.
In
particular embodiments, the angle 02 is from about 35 to about 50 .
[0091] In FIG. 21B, 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 . Put another way, a low energy mixing lobe 119 forms an
CA 02816723 2013-05-01
WO 2012/068466 PCT/US2011/061402
angle 0 between 5 and 65 relative to a longitudinal axis of the turbine
shroud
110. In particular embodiments, the angle 0 is from about 35 to about 50 .
[0092] Mixing lobes are present on the turbine shroud. If desired,
though,
mixing lobes may also be formed on a trailing edge 128 of the ejector shroud.
[0093] The present disclosure has been described with reference to
exemplary embodiments. Obviously, 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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