Note: Descriptions are shown in the official language in which they were submitted.
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TzTLE: OCEAN WAVE ENERGY EXrRACTtON
FIELD OF THE IrfVIIVIZON
The present invention relates in general to systems for hannessing and
converting
the energy from ocean waves to more useable energy forms such as electdc
power.
More particularly, the invention relates to wave powered energy extraction
systems and'the components thereof, in which the oscillating ocean wave motion
is
-used -to displace a volume of air to drive a wind operated turbine connected
to an
electrical generator. In the preferred form of the invention, the waves are
directed into
a specislly configured air compression chamber, in the outlet of which is
ansnged a
suitably operable wind turbine.
To this end the various aspects of the invention include: a novel wave
focusing
device; an air compression chamber arrangement particularly suited for use
with the
novel wave focusing device; and an independently novel wind turbine operable
to
rotate ltnidirecti.onally imder periodically reversing air flow conditions of
the kind
contemplated above.
It will be appreciated that whilst the various aspects of the znvention are
described herein as forming in combination a complete energy conversion
system,
each of these components, and in particuiar the turbine, may be suited to use
in other
unrelated applications. Alternatively, they may each be.incorporated into
similar
energy conversion systems when combined with new or existing alternative
component devices which are'not described in detail in this document.
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BACKGROUND OF THE E*,T'~ON
Concerns regarding the limited resources of traditional combustible
hydrocarbon
fuel sources and the damaging emissions resulting from their use, has prompted
considerable research into sustainable non-polluting energy sources such as
waves,
wind, tidal, geothermal and solar.
Whilst significant technological advances have been made in the conversion of
energy from some of these alternative areas such as wind and solar, the
majority of
wave powered generation systems proposed to date have not been physically
practical
andlor economically viable.
In this regard, numerous different types of wave powered generation systems
have been proposed, most of which are founded on the basic principle of using
the
vertical motion inherent in the movement of waves to effect a corresponcling
displacement of a component of the generating system. However, all of the
systems
proposed so far have had their limitations.
For example, one such system utilises oscillating floating paddles, the motion
of
which is converted directly or indirectly to electrical power. However, these
floating
paddle systems generaily have a low energy conversion efficiency and are
unable to
withstand adverse weather conditions. This means either that such systems are
limited
to coastal locations having only moderate and predictable wave patterns, or
that the
systems must be removed to a suitable shelter when storms are expected.
Other systems include those based on the concept of channelling the waves
through water displacement pumps, or alternatively into large accumulators or
reservoirs, the hydrostatic pressure of the stored water subsequently being
used to
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drive a turbine generator or the like. Again, the overall energy conversion
efficiency
is relatively low given the associated capital costs.
One of the most promising altermative types of systems proposed so far, on
which the present invention is based, are those in which the vertical movement
of the
waves is translated to rotary movement to directly or indirectly drive a
generator. In
these systems the rising and falling sea water is channelled toward and
harnessed
within an air compression chamber. The chamber has at its exit an outlet duct
or
venturi, in which is located a wind turbine of a kind operable to rotate
unidirectionally
under the periodically oscillating air flows induced by the wave motion.
Again, the main deficiencies with these latter wave driven air turbine
systems, is
the restricted overall achievable energy eff.tciencies. This is due primarily
to the
limitations f[rstly in the means of focusing the wave energy to maximise the
wave
displacement amplitude, and secondly in the operating efficiencies inherent in
the
turbine design.
In the first case, most of the prior art wave focusing devices have relied on
planar reflection of the wave front andlor channelling of the wave front
through a
narrowed opening such that the vertical displacement or amplitude of the wave
is
magnified. Others include various means to alter the formation of the sea bed
to
controllably disrupt the wave propagation, so as to thereby maximise the wave
amplitude at a predetermined location. Once again these types of systems have
been
lunited so far in respect of the maximum acbievable wave ampiification for a
given
level of capital expenditure.
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In the second case most prior art turbines are designed for constant velocity
rotation in response to fluid flow in one direction only, and as such are
unable to
operaxe continuously in response to the reversing fluid flow conditions
present in wave
powered applications of the kind discussed above. However, a number of
specially
configured unidirectional turbines have been designed for these reversing flow
conditions, the most commonly used devices being based on what is known as the
"Wells" turbine.
The original Wells turbine was of a monoplane axial fan type structure having
radially extending blades of an aerofoil section that are generally
symmetrical about
]o the chord line, where the blades are fixed with their planes of zero lift
normal to the
axis of the rotor. -
However, these early tucbines were known to suffer from stalling, often
resulting
in the shut down of the wave energy haznessing plant. This stalling occurs due
to the
fact that such a turbine needs to be designed around anticipated levels of air
flow,
whereas the size of the waves entering the turbine chamber cannot be
controlled for all
occasions. Therefore, when a larger sized wave enters the chamber, its
momentum
causes a correspondingly greater air flow rate through the turbine blades. As
the rate
-- - of rotation of the blades is unable, with its blade configuration, to
increase
correspondingly to counter this increased airflow, the angle of attack of the
airflow to
the blades increases beyond the stalling angle and the turbine shuts down.
Some later prior art devices have attempted to overcome this problem by
effectively insialling two monoplane Wells turbines in series resulting in a
bi-plane
turbine. - While this modified system solves the stalIing problem, it does so
at a
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penalty to the overall efficiency. This is because it sacriftces the first set
of blades by
allowing them to correspondingly stall and shut down, the second set of blades
then
continuing operation at a reduced pace and efficiency. This is due to the
total air flow
rate having now been decreased and smoothed out by the stalling and
interruption of
the air flow by the first turbine.
These prior art turbines also usually rely on a low revving high mass
construction in order to ensure smooth continuous rotation under periodically
reversing driving air flows of the kind contemplated.
It witl therefore be appreciated that most prior art turbines suited to this
type of
application are often quite complex in design and usually have severe
Iimitations in
relation to operating conditions and/or efficiencies.
It is an object of the present invention to provide a wave energy extracting
system and/or one or more of the components thereof, which overcomes or at
least
ameliorates one or more of the above discussed disadvantages of the prior art,
or at
I5 least offers a usefiilf alternative thereto.
DISCLOSURE OF THE INVENTTON
According to a first aspect of the invention there is provided a plane wave
focusing and amplifying structure, said structure com.prising an open sided
bay
bounded by a generally upright wall, the wall being configured at its inner
periphery
to define in plan section from the bay opening two converging arms of
generally part
parabolic curvature, wherein the axes of symmetry of each said paraboli from
which
the arms are derived are parailel and the arms are joined adjacent their
converging
ends to form a shared apex, said wall being oriented to admit an advancing
wave front
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in a direction generally parallel to said axes of symmetry, so that upon
reflection from
the wall the wave converges to an energy harnessing region near the apex at or
adjacent the focus of each of said paraboli, thereby amplifying the vertical
displacement of the wave at that region.
Desirably, the converging arms of part parabolic curvature are joined at the
shared apex by means of an end wall portion that also defines the rear wall
portion of
an air compression chamber, the front portion of the chamber preferably being
defined
by a front wall section that extends forward of the rear portion to
circumscribe a
predetermined area around the energy harnessing region, the front wall section
extending only partially below the anticipated water level so that the water
is able to
flow below the front wall and up into the chamber.
ln a preferred form the wall is configured to define in plan section at its
inner
periphery an end part of a single parabola or close approximation thereto,
wherein
upon reflection from the wall the waves converge in a region at or adjacent
the single
focus of that parabola.
In another form, that may be less costly to construct, the structure comprises
an
air compression chamber wherein the rear wall portion maybe formed in part by
the
existing coast line and the bay is defined simply by two possibly relatively
short arms
of part parabolic curvature extending from the chamber walls. Generally, any
compromise on the length of the parabolically curved auns is compensated for
by
extending the plan area of the air compression chamber that circumscribes the
energy
harnessing region.
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Preferably, the bay is further bounded at its base by a generally planar sea
bed
that is of constant depth along a direction generally perpendicular to the
axis of
symmetry of the parabola. The depth and inclination (if any) of the sea bed
can vary
according to local strata and wave conditions, as well as the maunen in which
the
amplified waves are to be harnessed for energy extraction. The general aim
will be to
optimise local conditions to maximise the wave rnagnification, ideally without
the
waves breaking prior to entering the harnessing region. For example, in one
preferred
form, the sea bed may.slope upwardly toward the harnessing region to assist in
further
forcing the water upwardly at that location. -
Preferably, the focal length of the parabola should be less than or equal to
1/7 of
a wave length of the incoming waves, which in a majority of cases results in a
focal
length of between 5 and 15 metres.
According to a second aspect of the invention there is provided a turbine
operable to rotate unidirectiona(Iy when subjected to reversing generally
axial fluid
flows therethrough, said turbine included a rotor comprising:
a cent.ral hub;
a plurality of straight radially extending aerofoil sectioned blades each
connected with said hub;
the cross section of each of said blades being approximately symmetrical about
a
line defining the maximum camber height and generally constant along its
radially
extending length;
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whereby the approximately symmetrical shape of the blades and their
orientation
in relation to the hub facilitates unidirectional rotation of the rotor in
response to
reversing axial fluid flows therethrough.
Preferably the blades are each connected with tb.e hub such ti}at the included
angle between the chordal plane of said aerofoil section and the axis of the
hub is
between 00 and 90 and more preferably between 0 and, say, 45 .
Desirably, the above discussed maximum included angle is adjustable and
further can preferably be reversed in synchronisation with the reversing fluid
flow, to
thereby optimise the angle of attacTt for the Duid flow in both directions.
It will be appreciated that reversing of the blade pitch can be achieved in
numerous ways including, for example, the use of a motor driven bevel gear
assembly
disposed to rotate a central spigot on which each blade is mounted. In another
variation, each blade is mounted on a spigot having an offset operating arm
which
cooperates with a helically splined actuating shaft which is reciprocally
movable along
the axis of the rotor.
In one preferred form suited to a particular set of conditions, the maximum
inciuded angle is between +30 and -30 and is reversible to conespond with the
reversing fluid flow. In another preferred form, particularly suited for
applications of
the kind described herein, in which the working fluid is a gas such as air,
the reversal
of the blade pitching is by means responsive to a pressure transducer disposed
to
detect the point of reversal of the gas flow.
Desirably, the blades are equi spaced about the central hub. In some preferred
forms suited to particular applications, the rotor has between 4 and 16
blades. The
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solidity can be highly variable often falling in the range of between 0.2 and
0.8. The
preferred blade chord ratio is 18%; and the preferred blade profile comprises
two
merged front halves of a standard NACA 65-418 aerofoil.
According to a third aspect of the invention there ~s provided an ocean wave
energy extracting system, said system including:
wave focusing means to magnify the periodic vertical peak to trough
displacement of incoming waves at a predetennined plan location t3efini.ng an
energy
harnessing region;
an air compression chamber having a generally submerged water inlet disposed
at or closely adjacent said haxnessing region to -admit the periodically
oscillating
waves so as to displace a volume of air thereabove to thereby generate a
correspondingly periodic reversing air flow;
said compression chamber also having an air outlet in which is located an air
driven turbine operable to rotate unidirectionally in response to said
reversing air flow.
Desirably, the turbine is one configured in accordance with the second aspect
of
the invention.
Preferably, the wave focusing means comprises a generally parabolic plane
wave focusing and amplifying structure in accordance with the first aspect of
the
invention wherein the focus of the parabola falls within the predetermined
plan
location.
Desirably, the air compression chamber is configured to converge from the
water inlet toward the air outlet so as to acceierate the air flow. In one
preferred form,
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the chamber includes a venturi adjacent its outlet in the throat of which is
disposed the
air driven turbine.
In other preferred forms, the air compression chamber outlet andlor the
shrouding and/or stators associated with the turbine, may include guide vanes
to
t
optimise the direction of air flow into and/or out of the turbine.
BRIEF DESCRIPTION OF THE DR.A'VINGS
Preferred embodiments of the invention will now be described, by way of
example only, with reference to the accompanying drawings, in which:
Figure 1 is a schematic plan view of a:&rst embodiment wave focusing and
t o amplifying structure in accordance with a first aspect of the invention
wherein the wall
arms from the bay opening are formed by two part parabolic sections having
parallel
and spaced apart axes of symmetry.
Figure 2 is a schematic computer generated perspective view of a second
embodiment plane wave focusing and amplifying structure in accordance with the
frst
aspect of the invention wherein the wall is defined generaIly by an end
portion of a
single parabola, illustrating the maximum wave trough displacement achievable
at the
harn.essing region;
Figure 3 is a schematic computer generated perspective view of the structure
shown in Figure 2, illushating the maximum wave peak displacement achievable
at
the energy harnessing region;
Figure 4 is a graphical scaled representation of the second embodiment plane
wave parabolic wave focuser as shown in figures 2 and 3;
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Figure 5 is a schematic sectional plan view of a third embodiment plane wave
part parabolic wave focusing and amplifyi.ug structure;
Figure 6 is a schematic perspective view of a fcrst embodiment turbine rotor
in
accordance with a second aspect of the invention, wherein the blades are fixed
at an
included angle of 0 to the axis of the central hub;
Figure 7 is a schematic perspective view of a second embodiment turbine rotor
in accordance with the second aspect of the invention, wherein the blade pitch
is
adjustable and can be reversed in response to the reciprocating air flow
through the
turbine;
Figure 8 is a part view of the turbine rotor Figure 7 showing one blade and
its
connection to the hub;
Figure 9 is a schematic transverse section of one blade of the turbine rotors
shown in Figures 6, 7 and 8;
Figure 10 is a schematic sectional view showing a first embodiment turbine
blade pitch variation and reversal mechanism;
Figure 11 is a part plan view of the mechanism shown in Figure 10;
Figure 12 is a schematic view showing a second embodiment turbine blade pitch
variation and reversal mechanism;
Figure 13 is a part plan view of the mechanism shown in Figure 12; and
Figure 14 is a schematic sectional view of a first embodiment ocean wave
energy extracting device in accordance with the third aspect of the invention;
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PREFERRED EMBODMENTS OF THE RqVENUON
Referring firstly to Figure 1, there is shown a first embodiment wave focusing
structure in accordance with the first aspect of the invention denoted
generally by
reference numeral 1.
The structure I comprises an open sided bay 2 bounded by a generally upright
sea wall 3. The wall 3 is concavely curved at its inner periphery 4 to define
in plan
two converging arms 5 of generally part parabolic curvature, wherein the
respective
axes of symmetry 6 and 7 of the paraboli from which the arms are derived are
parallel.
The arFns 5 are joined adjacent their converging ends to form a shared apex 8.
The
l4 wall 3 is oriented to admit an advancing wave front that is propagating in
a direction
generally parallel to the axes of symmetry 6 and 7.
Figure 5 shows another variation on the structure illlustrated in Figure 1
which
may be employed when it is too costly or not possible to construct the wall of
the bay
as either part of the surrounding coastline or having long parabolic arms
extending out
into the bay. In this instance a compromise is reached by constructing
relatively short
part parabolic arms 5 which connect directly to a shared apex 8 which
simultaneously
forms the rear wall portions of an associated air compression chamber shown in
plan
section at 11.
Figures 2, 3 and 4 show a-preferred form where the structure is formed as an
end
portion of a single parabola or close approximation thereto having a single
focus 9.
Waves in the ocean contain enormous amounts of energy, but since they are
generally plane waves, the energy in each crest is spread out along that
crest. The aim
of the parabolic or part parabolic wave focusing and a3oaplifying structure of
the fnst
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aspect of the invention, is to transport or converge that energy to one
centralised
region from which that energy can be more readily harnessed.
In use, the wave focusing structure is orientated as described, such that the
plane
wave advances toward the parabolic or part parabolic wall 3 in a direction
generally
parallel to the axis (or axes) of symmetry 6 and 7. On impact with the
parabolic
sections 5 of the wall 3, the wave is reflected to converge toward the
corresponding
facua 9 or foci 9 and 10 of each respective parabola. When the.wall defines
part of a
single parabola as in the preferred second embodiment shown in Figures 2, 3
and 4,
the wave converges toward the single focus 9 as a circular or polar wave. At
this
point, the displacement amplitude of the wave wiil have been significantly
magnified,
making it the perfect plan location at which to position suitable means for
converting
that sea water displacement to another more useable energy form. This is
defined as
the energy harnessing region shown generally at 12 which in Figure 5
corresponds in
location with air compression chamber 11. It will be appreciated that the plan
size of
this region is not fixed and its determination will depend in part on the
achieved
energy spread within this area.
It should be noted that there are a few conditions which need to be met so as
to
achieve maximal energy focusing with the generally parabolic or part parabolic
wave
focusing and ampiifying structure described above.
Firstly, the wave crests should ideally be propagating closely paraliel to the
or
each parabola's axis of symmetry 6 and 7. It appears slight variations can be
tolerated
with little loss of energy, but the greater the angle between the axis or axes
of
symmetry and the wave propagation direction, the more spread out will be the
area of
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energy concentration malcing the system less efficxent. This is not generally
a major
concern providing the wave focusing structure is correctly oriented at
installation, as
waves at the coast do not vary their angle of incidence greatly due to the
approach
bathometry.
Once the section of the plane wave enters the domain of the parabola, the sea
bottom should ideally be reasonably flat or planar across the axis of the
parabola or
paraboli, so as not to disturb the wave direction, and of suffcient depth or
otherwise
configured to prevent the wave crests from breaking prior to entering the
harnessing
region as they grow due to non-linear effects. Preliminary investigations have
to indicated that for one particular application a depth at the bay opening of
approximately 6 metres should be sufficient in most but the biggest of surf
conditions.
If the energy is initially scattered due to a very choppy and irregular
incoming
wave, then some energy will be scattered away from the focus or foci 9 and 10.
The
loss of energy due to this or to any of the above-mentioned conditions can be
lessened
by choosing the focal length appropriately, so that the waves do not have time
or the
space in which to vary greatly within the parabolic domain. Once again
pretiminary
investigations have indicated that a focal length of roughly 1/7 of wave
length should
be suitable in a wide variety of applications. As wave lengths are typically
35 to 105
metres, this translates to a focal length of about 5 to 15 metres.
The potential of a wave focusing device.of this kind is significant, computer
simulations indicating that 24% more energy flows into the parabolic domain
than
exists in a non focused wave of a length corresponding to the opening width of
the
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parabola. This translates to a wave magnification of the order of 3. Tests to
date have
shown that a magnification factor of 2.5 is readily achievable.
However, it is appreciated that in reality there will be losses that will
prevent the
maximum theoretical energy Tevels from being obtained For example, in
practical
operation of the single parabola structure, the circular wave which converges
on the
focus will not, in fact, be a full circle, as there will be a missing sector
on the open
ocean side. At the edges of this missing sector there will be some diffraction
of
energy into the domain of the parabola. There may also be losses due to
interfering
wave reflection from coastal structures located adjacent the parabolic bay and
irregtilarities in the sea bed.
Preferred means of achieving that energy extraction and conversion will be
described hereinafter with reference to the second and third aspects of the
invention
and Figures 6 to 14 relating thereto.
Turning to Figure 6, there is shown a rotor 20 of a first embodiment turbine
in
accordance with the second aspect of the invention operable to rotate
unidirectionally
when subjected to reversing generally axial fluid flows therethmugh.
The rotor 20 includes a central hub 21 having an axis 22 extending from which
are a plurality of straight radially extending aerofoil sectioned blades 23.
Desi.rably, the blades 23 have an aerofoil section of the general
configuration
illustrated in Figure 9 having on one side a generaily planar surface 24 and
on the
opposing, side a generally convex surface 25. The chord line, which also
denotes what
will be referred to as the longitudi.nally extended chordal plane of the
blades, is shown
generally._at 26. As shown, the cross-section of each of the blades is also
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approximately symmetrical about a line 27 def ning the maximum camber height
of
the blade section and is also generally constant along its radially extending
length.
The fxst embodiment illustrated in Figure 6 has the chordal plane of each of
the
blades straightly aligned;with or parailel to the central hub axis 22, that is
at an
included angle of 0 . In this manner, air flow entering the turbine from
either axial
direction will have the same angle of incidence with the rotor blades 23 and
effect the
same resultant rotation of the rotor.as marked. In this regard, the net force
exerted in
each flow direction on the generally planar blade surface 24 as the fluid
flows by, due
to the Bernoulli effect and the resultant pressure difference between the
planar and
convex sides of the blades, will be in the same direction, the magnitude
depending on
the relative air flows in the two opposing directions.
Whilst this fixed blade configuration may be satisfactory for various low
speed
app.lications, as the speed of rotation of the rotor increases, the angle of
attack of the
driving flow will no longer be optzmal, thus effecting the operational
efficiency of the
turbine.
In order to address this problem, a second variable pitch embodiment of the
invention has been proposed as illustrated in Figures 7 and S. In this
embodiment,
each of the blades 23 are connected to the central hub 21 by means of a
centra.i spigot
28 or the like which, by means of some appropriate internal mechanism,
facilitates
rotation of the blade to thereby vary its pitch.
It should be noted that the mechanism for adjusting the blade pitch is
preferably
configured such that the pitch can be automatically reversed in
synchronisation with
the reversing fluid flow through the rotor, so that the angle of attack is
optiznised in
CA 02574781 2007-01-19
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both directions. Clearly, if the rotor is fixed for optisnisation in one
direction only, the
detrimental effect when the air flow is reversed would in most situations more
than off
set any benefits that could potentially be gained over the fixed parallel
blade
configuration shown in Figure 4.
Two suitable mechanisms are illustrated, by way of example only, in Figures 10
to 13. In this regard, Figures 10 and 11 show a simple arrangement whereby
each
blade 23 is secured by means of a sleeve 29 to a centrally located spigot 28,
which in
turn is rigidly connected to the rotor hub 21. Also rigidly connected to the
hub 21 is a
suitable motor 30 which drives an axially depending pinion gear 31. The pinion
engages a spur gear 32 which has an associated annular bevel gear 33 which is
able to
rotate freely around the central hub 21.
The sleeve 29 of the central spigot 28 of the blade 23 has at its end a
smaller
bevel gear 34 which engages the annular bevel gear 33. A similar arr'angement
is
provided for each blade. In this manner it is possible while the turbine is
rotating at
high speed, to vary the inclination of the blades relative to the axis of the
rotor by
means of the gear mechanism described.
Figures 12 and 13 illustrate an alternative arrangement whereby rotation of
the
blades 23 is effected by axial reciprocal movement of a diagonally splined
actuating
collar 35. The collar splines engage pins 36 mounted on off set actuating arms
37,
causing the blades to thereby rotate about the central spigot 28.
It will be appreciated by those sltilled in the art of turbine design, that
there are a
number of parameters which need to be evaluated for the particular conditions
and
energy content of each proposed application for a turbine of this type. These
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parameters include the aspect ratio of the blades (chord ratio), the chord
length of the
blade, the solidity of the turbine (effectively a blade length to hub diameter
ratio), the
number of blades, and the maximum angle through which the blades can turn to
the air
flow (ie. the lilade pitch). One example that has been proposed as suitable to
one
particular application has a blade chord ratio of 18%, a chord length of 0.4
zz-, a hub
diameter 1.2 metres, a blade length of 0.45 m, a total of 12 blades and
a=maximum
included angle between the chordal plane of the blades and the hub axis of 30
. The
preferred blade profile comprises two merged front half portions of a standard
NACA
65-418 aerofoil.
Moving next to Figure 14, there is shown a schematic sectional view of a first
embodiment ocean wave energy extracting systen140 in accordance with a third
aspect of the invention.
The system 40 includes a wave focusing means shown generally at 41 which is
used to magnify the periodic vertical peak to trough displacement of incoming
waves
at a predetermined plan location or h.amessing region 12 the centre of which
is
indicated by line 42.
Disposed at or closely adjacent the plan location 42 circumscribing the
harnessing region is an air compression chamber 43. The chamber has~ a
generally
submerged water inlet 44 and is sized such that on admission of the
periodically .
oscillating waves a volume of air 45 is thereby displaced to generate a
correspondingly periodic reversing air flow.
Desirably, the compression chamber converges toward an air outlet.46 in or
adjacent which is located an air driven turbine shown generally at 47.
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In use, the incoming waves are focused so as to magnify the periodic vertical
peak to trough displacement of the waves adjacent the location 42. In this
manner, a
zeciprocating body or column of water oscillates within the air compression
chamber
43 via the water inlet 44, thereby acting like a piston on the volume of air
45
thereabove. For example, on the upward stroke of the wave, the volume of air
45 is
displaced toward the air outlet 46, the converging chamber walls and ducting
causing
an acceleration of the displaced air flow. This accelerated air flow is then
forced
through the air driven. turbine, the rotation of which may be used to power a
generator
or the like. As the waves subside air is drawn downwardly into the chamber,
again
causing rotation of the turbine which has been configured to opezate
Unidirectionally
in response to the reversing air flows.
In the preferred form, the system utilises the parabolic wave focusing device
of
the first aspect of the invention and the unidirectional turbine of the second
aspect of
the invention. In this manner, the exceptional efficiencies of each of these
mechanisms is compounded to result in a highly viable wave energy extracting
process. _
However, as previously foreshadowed, it will be appreciated that each of the
components of the system and in particular the wave focusing device and the
turbine,
can each be used in other applications or in combination with alternative
devices not
2o described herein in detail. This is particularly relevant to the turbine
which may have
numerous unrelated applications for use with a wide range of operating fluids.
In summary therefore it will be appreciated that whilst each aspect of the
invention has been described with reference to specific embodiments, each of
these
CA 02574781 2007-01-19
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various aspects and indeed the combined system incorporating these aspects,
may be
embodied in a variety of different forms and still fall wit.hi.n the scope of
each aspect
of the invention as claimed.
