U.S. patent application number 15/134072 was filed with the patent office on 2016-10-20 for optimized accelerator-extractor pairs for fluid power generation.
The applicant listed for this patent is V Squared Wind, Inc.. Invention is credited to Robert M. Freda, Bradford Knight.
Application Number | 20160305247 15/134072 |
Document ID | / |
Family ID | 57129721 |
Filed Date | 2016-10-20 |
United States Patent
Application |
20160305247 |
Kind Code |
A1 |
Freda; Robert M. ; et
al. |
October 20, 2016 |
OPTIMIZED ACCELERATOR-EXTRACTOR PAIRS FOR FLUID POWER
GENERATION
Abstract
A device includes an extractor structurally configured to
extract energy from a fluid flow, an accelerator structurally
configured to accelerate a fluid stream through the extractor
thereby creating an accelerated fluid stream, and an extractor
feature structurally configured to minimize blockage of the
accelerated fluid stream. The extractor feature may include one or
more of a linear cascade, an oscillating foil, and an axial
extractor.
Inventors: |
Freda; Robert M.; (West
Roxbury, MA) ; Knight; Bradford; (West Roxbury,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
V Squared Wind, Inc. |
West Roxbury |
MA |
US |
|
|
Family ID: |
57129721 |
Appl. No.: |
15/134072 |
Filed: |
April 20, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62149821 |
Apr 20, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F03D 5/00 20130101; Y02E
10/70 20130101 |
International
Class: |
F01D 1/04 20060101
F01D001/04; F01D 25/24 20060101 F01D025/24; F01D 5/14 20060101
F01D005/14 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] This invention was made with government support under
contract W911QY-13-C-0054 awarded by the Department of Defense. The
government has certain rights in the invention.
Claims
1. A device comprising: an extractor structurally configured to
extract energy from a fluid flow; an accelerator structurally
configured to accelerate a fluid stream through the extractor
thereby creating an accelerated fluid stream; and an extractor
feature structurally configured to minimize blockage of the
accelerated fluid stream, the extractor feature including one or
more of a linear cascade, an oscillating foil, and an axial
extractor.
2. The device of claim 1 wherein the extractor feature is
structurally configured to minimize individual extraction plane
flow effects by reducing individual plane solidity.
3. The device of claim 2 wherein the extractor feature includes the
linear cascade, the linear cascade including two or more co-planar
blades and a stage solidity of less than 20%.
4. The device of claim 2 wherein the extractor feature includes the
oscillating foil, the oscillating foil including two or more
co-planar foils and a stage solidity of less than 20%.
5. The device of claim 2 wherein the extractor feature includes the
axial extractor, the axial extractor including two or more
co-planar collapsible foils and a stage solidity of less than
20%.
6. The device of claim 1 wherein the extractor feature is
structurally configured to minimize blockage by minimizing flow
effects engendered by power extraction.
7. The device of claim 6 wherein the extractor feature extracts
power from a mono or bidirectional radial motion.
8. The device of claim 7 wherein the mono or bidirectional radial
motion includes a linear cascade.
9. The device of claim 6 wherein the extractor feature extracts
power from an axial motion.
10. The device of claim 9 wherein power from the axial motion is
extracted by one or more of a piston and collapsible kite
configuration or an electrostatic system.
11. The device of claim 6 wherein the extractor feature extracts
power from a combination of axial and radial motion.
12. The device of claim 11 wherein the combination of axial and
radial motion is caused by one or more of an oscillating foil or an
unsteady aerodynamics configuration.
13. The device of claim 1 wherein the extractor feature is
structurally configured to extract power from a volume by utilizing
multiple extraction planes.
14. The device of claim 1 wherein the extractor feature is
structurally configured to minimize flow effects by minimizing a
size of one or more extractor elements relative to boundaries of
the accelerator and other extraction planes.
15. The device of claim 14 wherein the flow effects include
wakes.
16. The device of claim 1 wherein the extractor feature is
structurally configured to reduce individual plane solidity to
minimize individual extraction plane flow effects.
17. The device of claim 1 wherein the extractor feature is
structurally configured to limit flow effects to an outside of a
swept area by increasing a number and reducing a size of one or
more extractor elements.
18. The device of claim 1 wherein the extractor feature is
structurally configured to counterbalance effects to an outside of
a swept area in at least one of a two-dimensional or
three-dimensional anhedral configuration thereby reducing one or
more of a tip leakage or a tip vortex expansion angle.
19. The device of claim 1 wherein the extractor feature is
structurally configured to minimize blockage between extractor
elements by changing a geometry of an extractor blade row from a
nozzle to one or more of a tube or diffuser configuration that
utilizes an axial offset in one or more of a spiral or angled
configuration.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional App. No. 62/149,821 filed on Apr.
20, 2015, the entire content of which is hereby incorporated by
reference.
TECHNICAL FIELD
[0003] The present disclosure generally relates to devices,
systems, and methods for maximizing power output from
accelerator-extractor pairs in fluid flows.
BACKGROUND
[0004] The power performance of fluid accelerator-extractor systems
is generally determined by the rate of blockage experienced by the
accelerator due to the extractor. This rate of blockage is
generally a combination of a given rate of power extraction (power
blockage) and the specific flow field engendered by extracting
power (non-power blockage) with a given extractor. In free stream
turbines the axial induction (a) (a way of characterizing blockage
relative to the swept area or max area of a given device) and the
power coefficient are similar until the higher power coefficients
at which point axial induction is less than the power coefficient.
The axial induction factor can be defined as the fractional
decrease in wind velocity between the free stream and an energy
extraction device, generally in the form:
a = v 1 - v 2 v 1 ##EQU00001##
[0005] The relationship between the axial induction and the power
coefficient can be depicted in a classic Betz graph comparing
P/P.sub.o to v.sub.2/v.sub.1.
[0006] Once an extractor is placed in an accelerator, however, this
relationship may no longer be based purely on the extractor, but on
the power extraction of the extractor and the extractor's
interaction with the accelerator. Therefore, the axial induction
and power coefficient may vary based on the interaction of a
particular accelerator-extractor pair. If blockage is high, the
axial induction can be significantly higher than the power
extraction coefficient related to the maximum area of the
accelerator (e.g., the maximum area comparison determines whether
the accelerator is providing any benefit to power production
compared to the same swept area free stream device) which has led
to erroneous conclusions about accelerators in the prior art. If
the blockage is above the critical point, where benefits can be
derived from accelerators, then the axial induction is higher than
the power coefficient (Cp). If blockage is reduced solely to the
blockage engendered by the power extraction, then the Cp can be a
multiple of the axial induction experienced by the device. For
example, an accelerator with a 2.times. area ratio (AR) with no
non-power blockage can have power coefficients that are six times
the axial induction of the device. Due to power blockage this Cp:a
ratio reduces as the Cp increases to the theoretical maximum.
[0007] In general, to date, no accelerator-extractor pair has
yielded a Cp that is significantly higher than the axial induction
(a) of the device. This is primarily due to the pairs that have
been examined in the field for the last 30 years or so. Prior
implementations are generally limited to pairing wide angle (e.g.,
20-40 degrees) diffuser augmented wind turbines (DAWTs) with axial
rotary extractors of between two and eight blades (horizontal axis
wind turbines (HAWTs), wind, or HATs, water). In addition to DAWTs
being inefficient accelerators (if the baseline acceleration in an
empty accelerator is too low relative to the AR, the device will
not achieve the critical point) HAWT/HATs engender highly
non-uniform flow with significant flow and momentum effects to the
outside of the device and therefore significant blockage and high
value of a when placed in accelerators. A further complication is
that improving the DAWT's accelerative capabilities by reducing the
expansion angle may increase interaction between the HAWT/HAT's tip
vortex wake spiral and the diffuser wall which dissipates the
wake's transport energy thereby stalling the wake in the diffuser
which through mass conservation engenders a reduction in intake
velocity and an increase in the value of a. Any interaction of the
extractor flow field with the walls of the accelerator anywhere in
the accelerator may induce blockage at the intake due to the
reduction in available transport energy and the communication of
such losses through the accelerator volume to the velocity at the
intake.
[0008] Due to this state of affairs it remains desirable to move
beyond the prior art and pair accelerators with extractor devices
that reduce the interaction between the pair, or to introduce
mechanisms on accelerators by which the effect of any interaction
can be counterbalanced (or both).
SUMMARY
[0009] A device includes an extractor structurally configured to
extract energy from a fluid flow, an accelerator structurally
configured to accelerate a fluid stream through the extractor
thereby creating an accelerated fluid stream, and an extractor
feature structurally configured to minimize blockage of the
accelerated fluid stream. The extractor feature may include one or
more of a linear cascade, an oscillating foil, and an axial
extractor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The foregoing and other objects, features and advantages of
the devices, systems, and methods described herein will be apparent
from the following description of particular embodiments thereof,
as illustrated in the accompanying drawings. The drawings are not
necessarily to scale, emphasis instead being placed upon
illustrating the principles of the devices, systems, and methods
described herein.
[0011] FIG. 1 shows a reversible camber oscillating airfoil with a
uniform guide path.
[0012] FIG. 2 shows a reversible camber oscillating airfoil with a
variable guide path.
[0013] FIG. 3 shows a reversible camber airfoil.
[0014] FIG. 4 shows a reversible camber airfoil.
[0015] FIG. 5 shows a linear array of oscillating airfoils.
[0016] FIG. 6 shows an array of oscillating airfoils.
[0017] FIG. 7 shows an array of oscillating airfoils.
[0018] FIG. 8 shows an array of oscillating airfoils.
[0019] FIG. 9 shows a spiraling geometry.
[0020] FIG. 10 shows a spiraling geometry.
[0021] FIG. 11 shows a device cycle for an axial extraction
parafoil.
[0022] FIG. 12 shows a PIV example of wall proximity blockage in a
Savonius turbine.
[0023] FIG. 13 illustrates effects of wall interaction with wake
energy.
[0024] FIG. 14 shows an effect of a non-uniform wake on a nozzle
function.
[0025] FIG. 15 depicts a two-dimensional linear modular array.
[0026] FIG. 16 shows single and double stage tilted linear
cascades.
[0027] FIG. 17 shows a CD nozzle with variable expansion and
vanes.
[0028] FIG. 18 shows a CD nozzle with variable expansion and
vanes.
[0029] FIG. 19 shows triangular circuit linear cascades.
[0030] FIG. 20 shows triangular circuit linear cascades.
[0031] FIG. 21 shows trends in nozzle performance with linear
cascades.
[0032] FIG. 22 shows simulation results for an energy
extractor.
[0033] FIG. 23 shows simulation results for a two stage energy
extractor.
[0034] FIG. 24 shows a graph illustrating the degree of
blockage.
[0035] FIG. 25 shows a device for fluid power generation.
[0036] FIG. 26 shows a device for fluid power generation.
DETAILED DESCRIPTION
[0037] The embodiments will now be described more fully hereinafter
with reference to the accompanying figures, in which preferred
embodiments are shown. The foregoing may, however, be embodied in
many different forms and should not be construed as limited to the
illustrated embodiments set forth herein. Rather, these illustrated
embodiments are provided so that this disclosure will convey the
scope to those skilled in the art.
[0038] All documents mentioned herein are incorporated by reference
in their entirety. References to items in the singular should be
understood to include items in the plural, and vice versa, unless
explicitly stated otherwise or clear from the context. Grammatical
conjunctions are intended to express any and all disjunctive and
conjunctive combinations of conjoined clauses, sentences, words,
and the like, unless otherwise stated or clear from the context.
Thus, the term "or" should generally be understood to mean "and/or"
and so forth.
[0039] Recitation of ranges of values herein are not intended to be
limiting, referring instead individually to any and all values
falling within the range, unless otherwise indicated herein, and
each separate value within such a range is incorporated into the
specification as if it were individually recited herein. The words
"about," "approximately," or the like, when accompanying a
numerical value, are to be construed as indicating a deviation as
would be appreciated by one of ordinary skill in the art to operate
satisfactorily for an intended purpose. Ranges of values and/or
numeric values are provided herein as examples only, and do not
constitute a limitation on the scope of the described embodiments.
The use of any and all examples, or exemplary language ("e.g.,"
"such as," or the like) provided herein, is intended merely to
better illuminate the embodiments and does not pose a limitation on
the scope of the embodiments or the claims. No language in the
specification should be construed as indicating any unclaimed
element as essential to the practice of the embodiments.
[0040] In the following description, it is understood that terms
such as "first," "second," "top," "bottom," "up," "down," and the
like, are words of convenience and are not to be construed as
limiting terms unless specifically stated to the contrary.
[0041] Described herein are devices, systems, and methods for
maximizing power output from accelerator-extractor pairs in fluid
flows. In general, a variety of linear extractors and other
non-rotary configurations for extracting power from a fluid flow
are disclosed. While the emphasis is on arrangements suitable for
extracting wind power from air flow, it should be understood that
the principles of this disclosure may be suitably adapted to other
fluid flows such as water or the like, as well as extractors used
without accelerators, restrictors, or the like.
[0042] As used herein, "non-power blockage" generally refers to the
difference between total blockage and a power blockage that has
been theoretically and/or experimentally isolated, unless
explicitly stated to the contrary or otherwise clear from the
context.
[0043] U.S. Pat. Pub. No. 2013/0334824 to Freda (hereinafter
"Freda") describes various geometric optimizations, modular
extractor configurations, and so forth. While the following
description may focus on non-rotary extractor configurations, many
aspects of Freda remain relevant to arrays of extractors using the
principles described herein. As such, U.S. Pub. No. 2013/0334824 is
hereby incorporated by reference in its entirety.
[0044] For example, in Freda, in general, geometric optimization
parameters for high efficiency (e.g., >90%) accelerators are
described. The diffusion angle on these accelerators may be between
8 and 2 degrees dependent on the AR of the given accelerator. These
accelerator parameters may be included herein as the geometric
optimization parameters for accelerators. Variance of these
parameters outside the optimum range of performance may reduce the
rate of acceleration and thereby available power. These parameters
may not be varied to accommodate the wake and overall flow field of
extractor devices without affecting the accelerative performance
until, as in the case DAWTs, the accelerative performance is
reduced to such a level that there is no benefit from the
accelerator.
[0045] Therefore the accelerator parameters may be largely fixed to
the previously described optimum geometries. Therefore, features
that improve performance of accelerator-extractor pairs may be
extractors that reduce flow field effects to the outside of the
extractor area and/or features introduced to the accelerator
geometry that may counteract the effects of the extractor.
[0046] As another example, in Freda various modular accelerator
array systems are generally described where the benefits from such
modular systems may be accrued to more efficient
extractor-accelerator pairs. The accelerator-extractor pairs may
include a modification of the systems described herein or may
adhere to parameters of the described systems. Any
accelerator-extractor pairs described herein may be applied if
geometrically feasible to either the prior or modified modular
systems.
[0047] In an implementation, a class of extractor systems that may
be paired effectively with accelerators is axial rotary devices
wherein the axial rotary devices may have about 3-128 blades, may
be of variable average chord width globally or locally, may be
n-staged counter-rotating or co-rotating, may vary blade number
between stages, may vary pitch globally or locally from about 75
degrees to about negative 5 degrees, may have blades pitched at
different average angles, may have global or local anhedral tilt,
may have global or local sweep, may be single or multi-element
airfoils or a combination thereof on single airfoil or single rotor
or a combination thereof, may be spiraled in n-helix or n-helix
segmented configurations, may include a stator or multiple stators,
may have a combination of propeller and rotor behavior, may be
n-staged propeller-rotor or rotor-propeller pairs, may vary in
radius, position, and type between rotor or rotor-propeller or
propeller-rotor stages, may be surfaced with aerodynamic
enhancement features (e.g., as described in Freda), may have a
cylindrical or n-polygonal tube hubs, may have hubs that extend to
about 50% of rotor radius, may be uniformly or non-uniformly geared
to generators exterior to the accelerator, may be attached to
generator(s) with modularly engaged groups or windings, may be
n-parafoil types, may have orthogonally and/or angled louvered
blades, may include pressure release channels, may have variable
chord dimensions outward and inward and orthogonally globally or
locally and uniformly and non-uniformly, may have shaped tips such
as u-tips or saw-edge tips or similar, and the like and may have
any combination of the above features.
[0048] In an implementation, a class of extractor systems that may
be paired effectively with these accelerators is radial rotary
devices where the definition of rotary may include without
limitation circular, elliptical, stadium, and linear paths and all
closed geometric variations therein, may have paths that are
oriented axially or radially internal or external to the
accelerator, may include mechanisms to control pitch relative to
axial flow locally or globally in a prescribed or adaptive manner,
may have bearing and the like paths, may have mag-lev paths, may
have invertible camber airfoils, may have about 3-200 blades, may
be of variable average chord width globally or locally, may be
n-staged counter-rotating or co-rotating (e.g., that draw power
from an internal volume rather than a single plane), may vary blade
number between stages, may vary pitch globally or locally from
about 75 degrees to about negative 5 degrees, may have blades
pitched at different angles, may have global or local anhedral
tilt, may have global or local sweep, may be single or
multi-element airfoils or a combination thereof on single airfoil
or single device or a combination thereof, may be spiraled or
tilted in n-helix or n-helix segmented configurations either
axially or radially, may have a combination of propeller and rotor
behavior, may include a stator, may be n-staged propeller-rotor or
rotor-propeller pairs, may vary in radius, position, and type
between rotor or rotor-propeller or propeller-rotor stages, may be
surfaced with aerodynamic enhancement features (e.g., as described
in Freda), may be uniformly or non-uniformly geared to generators
exterior to the accelerator, may be attached to generator(s) with
modularly engaged groups or windings, may be n-parafoil types, may
have orthogonally and/or angled louvered blades, may include
pressure release channels, may have variable chord dimensions
vertically and orthogonally globally or locally and uniformly and
non-uniformly, may have shaped tips such as u-tips or saw-edge tips
or similar, and the like and may have any combination of the above
features. Radial types may also be deployed within nozzles in
n-device arrays wherein the arrays may be n-staged uniformly or
non-uniformly in parallel or offset and may include tandem types
such as tandem arrangements of 2, 3, 4, . . . n oscillating foils
and the like, or may have any combination of the above
features.
[0049] In an implementation, a class of extractor systems that may
be paired effectively with these accelerators is axial motion
extractors where axial motion extractors may include any device
that extracts power through an oscillatory or non-oscillatory
motion in parallel to the flow and the like. This may include
electrostatic types, which may include ionic types or magnetic
particulate types and the like, or harmonic extractors, vibrational
or sinusoidal, or piston type extractors and the like. In an
embodiment, an axial oscillatory device may include flow resistive
aerodynamic shape such as a parafoil or airfoil or flat plate or
symmetrically angled flat plate and the like oriented orthogonally
or angled to the flow attached to a spring. The piston circuit may
be circular, elliptical, stadium, or linear, or may be freeform as
in the case of combination of tether types with magnetic
particulates. "Spring" or the like may be used generally herein to
describe any mechanism such as a spring or tether or other means of
recovery such as magnetic that can return the foil with the energy
stored in the mechanism. The foils may be of any scale within the
volume or may cover the volume vertically or horizontally. The foil
may have a cycle where the flow pushes the foil downstream against
the generator loading and spring resistance and is returned by the
recovery mechanism. The recovery mechanism may store the energy
enabling the system to extract power on the recovery cycle. A foil
device may include a collapsible foil where the foil may have a
hinge such as a pinned metal or pressed hinge or the like down the
centerline that may allow it to assume a flat or airfoil shape on
the recovery cycle which may limit losses. The down flow and
recovery cycle may be attached to a mechanism such as a gear or a
linkage crank to produce rotation in a generator shaft or the path
may be executed with a linear generator or the like to generate
power on both the down and recovery cycles and the like and may
have any combination of the above features. Axial motion extractors
may also be deployed within nozzles in n-device arrays where the
arrays may be n-staged uniformly or non-uniformly in parallel or
offset and the like.
[0050] An embodiment may also include uniform or non-uniform
spacing or tip gaps between the extractor and accelerator.
[0051] In an implementation, accelerator features that may reduce
or counteract blockage due to an extractor may include forward or
backward pitched elements on the outer or inner surface of the
accelerator such as the exit or entrance or throat and may include
linear or curved geometries such as a dimensionalized gurney flap
or the like applied to the three-dimensional accelerator geometry
or which may be positioned singly or in arrays and the like in
combination with previously described optimal accelerator
geometries, the forward or backward pitched elements as described
that may be uniform or non-uniform or variable solidity and have
porosity or edge features such as vortex generation geometries or
scalloping or corrugation or the like and any combination thereof,
may have variable thickness and curvature, may include pressure
release mechanisms such as drill-throughs or open areas in the
extractor region and the like or any combination thereof, may
include flow control mechanisms internal or external anywhere along
the length of the accelerator to control either the entrained flow
or the external flow such as a saw edge intake and the like, may
include active boundary layer mechanisms locally or globally
applied as are known in the art such a plasma or injection control,
may include passive mechanisms locally or globally applied as are
known in the art such as scalloping or surface dimpling, may
include any combination of passive and active flow control applied
either locally or globally, and the like as are known in the art
and may have any combination of the above features and features
included by reference in the aforementioned patents and patent
applications. The accelerators may be two-dimensional or
three-dimensional accelerators with variable thickness inside and
outside, they may have different curvature outside or inside, they
may be deployed singly or in an array. The elements pitched forward
or backward can be placed anywhere on the accelerator geometry and
may range in geometry from a flat plate, to concave or convex on
either side, where thickness and element shape can vary across the
element.
[0052] All accelerator extractor pairs described herein may be
deployed in two-dimensional or three-dimensional arrays. Adjustment
of the vertical to horizontal aspect ratio may allow granular
control of the value of power density per m 2 horizontal surface.
When blockage is resolved at a sufficient rate the power density of
the modular arrays at a 2:1 aspect ratio may equal the power
density of coal and is 30% of the power density of natural gas.
[0053] By way of specific examples:
[0054] a) high rpm (>500) three bladed horizontal rotors or
H-type darrius vertical, 4 N thrust free stream, 90% blockage and
.about.15% Cp.
[0055] b) linear cascades at low rpm (.about.100), 4 N thrust free
stream, 35% blockage and .about.55% Cp.
[0056] c) 25% Screen, 4 N thrust free stream, 15% blockage and the
pressure drop across the screen indicates a .about.140% Cp.
[0057] An example is shown, e.g., in FIG. 22, where a 2.25 AR
nozzle (including flap) is producing 66 watts, axial induction
0.33, and a Cp of 0.56. Thrust model for a 2.25 with a baseline
acceleration of 1.75 yields 66 watts, 0.3 axial induction, and Cp
of 0.56. Both throat velocities are .about.6.5 for free stream of
4.5. Two stage linear cascades in the free stream produce an axial
induction of 0.12 for a Cp of 0.2. They maintain roughly this a:Cp
ratio in accelerators.
[0058] The cascade also gives an example of a device that does not
have three-dimensional uniform rotational effects across the
device. The asymmetric effects make it easier to see the structure
and its effect within the accelerator; see, e.g., FIG. 22, which
shows a single row showing the asymmetric flow in the free stream
and accelerator. The single rows are more efficient until the
cascade effects take over at certain RPMs or AR ratios. Once the
device flow effects dominate the function and expansion of the
accelerator the efficiency may drop rapidly.
[0059] FIG. 24 shows the effect of AR on Cp when sufficient
blockage has been resolved, as in the linear cascades.
[0060] If the total blockage (the pair's axial induction) is around
or greater than the Cp then AR increase results in lower Cp's. If
blockage is less than Cp due to a reduction in the extractor
interaction then the Cp increases with AR until the accelerator
geometries become problematic. The slope of the Cp to AR (the line
in FIG. 24) reflects the degree of blockage in the pair engendered
by the extractor.
[0061] This trend is predicted by the tube/accelerator thrust model
as the requisite mass flow coefficient required to reach the
minimum benchmark is lower as AR increases. These results are not
optimized as extractor parameters are held stable, 60 degree pitch,
2 stages, counter-rotating, blade number of 12. The value 0.20 at 1
is the free stream rotor specific performance. In this graph, the
AR includes the flap. The FIG. 23 graph is of best case at each AR.
Solidity increase of 2 rows and/or the AR increase does not yield a
corollary increase in overall axial induction as previously
predicted in the art. A variety of linear or other non-rotary
extractors may be usefully devised to extract wind power without
the use of turbines.
[0062] FIG. 1 shows a reversible camber oscillating airfoil with a
uniform guide path. The system, which is generally shown in
multiple views in the figure (a first view 100, a second view 101,
and a third view 103), may, for example, use non-flexible arc foils
102 such as NACA 9501 or the like (the foils 102 may also be
referred to herein as airfoils). As illustrated, the foil 102 may
be secured to an endplate 104 (or multiple endplates 104, e.g., on
opposing ends), and have an oscillating motion cycle 106 that
rotates about bearing blocks 108 (e.g., linear bearing blocks) or
the like between two positions defined by mechanical stops such as
pitch restraint pegs 110 or the like. A turning peg 111 may act on
the endplate 108 from a top of the foil 102 to support an
oscillating motion cycle 106.
[0063] FIG. 2 shows a reversible camber oscillating airfoil with a
variable guide path. Specifically, this figure shows three
positions (a first position 200, a second position 201, and a third
position 203 of a foil 202). In this embodiment, a turning peg 211
may act on the endplate 204 at a bottom of the foil 202 as
generally illustrated to support an oscillating motion cycle 206.
The figure also shows the bearing block 208 (e.g., linear bearing
block) and pitch restraint pegs 210.
[0064] FIG. 3 shows a reversible camber airfoil. In this system
300, the foil 302 may be a flexible foil, with foil parameters
controlled with rigid LE and TE elements 312 in combination with
the elastic modulus of the flexible foil section 314. The turning
peg 311 and pitch restraint peg 310 may act on the endplate(s) 304
to support an oscillating motion cycle 306 on linear bearing blocks
308.
[0065] FIG. 4 shows a reversible camber airfoil. In general, an
entry cycle 400 and an exit cycle 401 may be fixed by wind, with an
intervening turning cycle 403 generating rotational motion. The
foil may be flipped thereby providing a flipped foil 405 as shown
in the figure.
[0066] FIG. 5 shows a linear array of oscillating airfoils. A foil
array 500 can be used with either a camber system or flat plates,
and may include a number of foils 502 in a line or other linear or
non-linear arrangement. These foils 502 may also be mechanically
coupled to one another (e.g., via an array endplate 514), or these
foils 502 may be independently operable. The figure further shows
the foil endplates 504, foil endplate couplers 505, a bearing block
508 (e.g., a linear bearing block), a pitch restraint peg 510, and
a turning peg 511 that acts on the endplate 504 of the foil
502.
[0067] FIG. 6 shows an array of oscillating airfoils. As
illustrated, these oscillating foils 602 may be placed in the
throat 616 of a restrictor, nozzle, or the like to increase air
flow about the foils, and the airfoils may oscillate in tandem
either through mechanical coupling or aerodynamic coupling.
[0068] FIG. 7 shows an array of oscillating airfoils. As
illustrated, any number of tandem airfoils 602 may be used, such as
two airfoils, four airfoils, six airfoils, and so forth. The
airfoils may be disposed in the throat 716 of a restrictor, nozzle,
or the like to increase air flow.
[0069] FIG. 8 shows an array of oscillating airfoils. In
particular, eight tandem oscillating airfoils 802 are depicted in
the throat 816 of a restrictor, nozzle, or the like.
[0070] FIG. 9 shows a spiraling geometry. In particular, in a first
spiraling geometry 900, a nozzle 920 is depicted with a zero offset
between foils 902 as shown by the first line 922. As shown in the
first spiraling geometry 900 of the figure, the axial LE to LE may
be the same for the foils 902. In a second spiraling geometry 902,
the nozzle 920 or tube is depicted with a ten degree offset
(relative to a direction of fluid flow) between two sequential
airfoils as shown by the second line 924 offset from the first line
922. As shown in the second spiraling geometry 902 of the figure,
the axial LE to LE may be the same for the foils.
[0071] FIG. 10 shows a spiraling geometry. In particular, the
figure shows a first view 1000 illustrating a full isometric view
of the geometry and a second view 1001 showing a variety of
segmented views of the geometry.
[0072] FIG. 11 shows a device cycle for an axial extraction
parafoil. As depicted, the parafoil may open and close on a hinge
1102 or the like to provide cycles of linear displacement, e.g.,
against a spring, coil or the like, and relaxation. Thus, the foil
may open at a hinge as shown in step 1, and may be drawn linearly
in a direction of fluid flow. This linear motion may be converted
on a spool or the like into a rotational motion to drive a
generator. In the return cycle (step 3), the foil may return to an
initial position, e.g., through a spring or the like on the spool,
or otherwise using a portion of the power extracted during the out
cycle (step 2). Once the foil has returned to the starting position
(step 4), the process may return to step 1 and the hinge may be
open to once again capture force from an incident fluid flow.
[0073] FIG. 12 shows a PIV example of wall proximity blockage in a
Savonius turbine. In particular, a first top view 1200 of a
vertical axis wind turbine blade is shown in a 25% open channel,
and a second top view 1201 of a vertical axis wind turbine blade is
shown in a free stream without adjacent walls. As shown in this
figure, substantial blockage may be evident around the tips of the
turbine blade that are adjacent to the wall even with 25% of linear
open space around the blade tips.
[0074] Thus, as demonstrated by FIG. 12, use of vertical extraction
devices, e.g., vertical axis turbines may be used in the devices,
systems, and methods described herein. For example, this may
include Savonius turbines or the like, or otherwise vertically
mounted airfoils.
[0075] The devices, systems, and methods described herein may also
or instead include two or more sequential rotors on a common axis.
For example, the common axis may be a horizontal axis, thereby
creating a horizontal extraction device. In another aspect, the
common axis may be a vertical axis. In certain aspects, sequential
rotors may rotate in the opposite direction of one another, thereby
creating a multi-stage extraction device, e.g., a multi-stage
horizontal extraction device. For example, one aspect includes a
two stage assembly, where the second stage rotates in the opposite
direction of the first stage. Considerations for the design of such
assemblies include without limitation power extraction performance,
cost, manufacturability, reliability, maintenance requirements, and
so forth.
[0076] In multiple rotor assemblies as described herein, multiple
sets of rotor blades may be disposed on the same shaft (such as in
a steam turbine), or multiple sets of rotor blades may be disposed
on multiple shafts, e.g., multiple horizontal shafts.
[0077] FIG. 13 illustrates effects of wall interaction with wake
energy. In general, blockage may be caused by the wall interaction
with wake energy caused by the turbine, e.g., at the tips of the
turbine blades. The interaction may be affected by anhedral tilt.
The figure shows a first image 1300 illustrating an anhedral tilt
rotor at forty degrees and a second image 1302 illustrating an
anhedral tilt rotor at twenty degrees 1310. At forty degrees, the
blockage may be equal to 0.55 with a Cp=0.31 intake; at twenty
degrees, the blockage may be equal to 0.65 with a Cp=0.2 intake.
Diffuser acceleration and interaction may include, for example, a
low interaction and a high interaction. An example of a low
interaction may include a relatively short diffuser with a
1.3.times. baseline and a Cp=0.54 exit. An example of a higher
interaction may include a relatively long diffuser with a
1.8.times. baseline and a Cp=0.31 exit.
[0078] FIG. 14 shows an effect of a non-uniform wake on a nozzle
function. In particular, a first accelerator 1400 and a second
accelerator 1402 are shown. The first accelerator 1400 may include
a rotor with a relatively low velocity through the constriction.
The second accelerator 1402 may include a relatively high velocity
through the same constriction as the first accelerator 1400, where
the rotor of the second accelerator 1402 is replaced by a radial
screen of equal area. The first accelerator 1400 may include a
cross-section rotor in a 2.75 area ratio accelerator, where the
freestream thrust is 4.5 N, the thrust blockage is 0.25, and the
blockage is 0.63. The second accelerator 1402 may include a
cross-section radial screen in a 2.75 area ratio accelerator, where
the freestream thrust is 3.7 N, the thrust blockage is 0.21, and
the blockage is 0.27.
[0079] FIG. 15 depicts a two-dimensional linear modular array.
Specifically, the figure shows a linear modular array 1500 and a
velocity profile 1502 through the array.
[0080] FIG. 16 shows single and double stage tilted linear
cascades. Specifically, the figure shows two models, a first model
1600 showing a single stage tilted linear cascade, and a second
model 1602 showing a double stage tilted linear cascade.
[0081] FIG. 17 shows a converging/diverging (CD) nozzle 1700 with
variable expansion and vanes 1702.
[0082] FIG. 18 shows a CD nozzle with variable expansion and vanes.
The nozzle 1800 may include vanes 1802 offset at about 6 degrees
from a longitudinal axis 1804 through the nozzle 1800.
[0083] FIG. 19 shows triangular circuit linear cascades.
Specifically, the figure shows a first cascade 1900 and a second
cascade 1902. The first cascade 1900 may include a triangular
circuit linear cascade in the general shape of an asymmetric
isosceles (20:12 degree). The second cascade 1902 may include a
triangular circuit linear cascade in the general shape of an
asymmetric isosceles (20:-15 degree).
[0084] FIG. 20 shows triangular circuit linear cascades.
Specifically, the figure shows a first cascade 2000 and a second
cascade 2002. The first cascade 2000 may include a triangular
circuit linear cascade in the general shape of an asymmetric
isosceles (20:12 degree, tube arrangement). The second cascade 2002
may include a triangular circuit linear cascade in the general
shape of an asymmetric isosceles (30:-15 degree, nozzle offset
arrangement).
[0085] FIG. 21 shows trends in nozzle performance with linear
cascades. Specifically, the figure shows a graph 2100 and a table
2102 showing trends and examples of nozzle performance with linear
cascades. The bars on the graph 2100 represent the power
coefficient (max area power) and the points (*) connected by lines
represent axial induction. The table 2102 shows, for example case
numbers, each of the stage, row tilt, and AR.
[0086] FIG. 22 shows simulation results for an energy extractor.
Specifically, the figure shows a first model 2200, a second model
2210, a first set of data 2202 for an example case, and a second
set of data 2212 for an example case. For the first model 2200, the
maximum theoretical at Cp=0.3 may be 121 watts, where a=0.21, vmax
is 7.12, and thrust is 17.3 N. Performance on cylinders at
Cp.about.0.5. thrust thus appears to overestimate. For the second
model 2210, the structure may match that of PIV of louver flow (not
rotational).
[0087] FIG. 23 shows simulation results for a two stage energy
extractor. Specifically, the figure shows a first model 2300, a
second model 2310, a first set of data 2302 for an example case,
and a second set of data 2312 for an example case. For the first
model 2300, there may be similar axial induction for greater than
two times the solidity in a two-stage linear cascade. This may
include an `a` ratio of 1.13 and a solidity ratio of 2.2. As shown
in the second model 2310, counter-rotating appears to make the flow
more symmetrical. Thus, the one-stage may be split into two with
the same blade count.
[0088] FIG. 24 shows a graph illustrating the degree of blockage.
Specifically, the graph 2400 shows an example of the effect of AR
(shown on the x-axis 2402) on Cp (shown on the y-axis 2404) when
sufficient blockage has been resolved, e.g., as in the linear
cascades. If the total blockage is around or greater than the Cp
then AR increase may result in lower Cp's. If the blockage is less
than Cp (e.g., due to a reduction in the extractor interaction)
then the Cp may increase with AR until the accelerator geometries
become problematic. The slope of the Cp to AR (the line 2406) may
reflect the degree of blockage in the pair engendered by the
extractor.
[0089] FIG. 25 shows a device for fluid power generation. As shown
in the figure, the device 2500 may include an extractor 2502, an
accelerator 2504, and an extractor feature 2506 that may provide
for optimized fluid power generation for the device 2500.
[0090] The figure also shows a first fluid flow 2508 into the
device 2500 (v.sub..infin.) and a second fluid flow 2510 out of the
device 2500 (v.sub.wake). The figure further shows a first area
bounded by a first dashed line 2512 that represents a maximum area
reference plane of the outer streamtube, and a second area bounded
by a second dashed line 2514 that represents a disk area reference
plane of the inner streamtube.
[0091] The extractor 2502 may include any as described herein or
otherwise known in the art, e.g., a turbine, a rotor, a fan, and
the like. In general, the extractor 2502 may be structurally
configured to extract energy from a fluid flow. The fluid flow may
be any as described herein or otherwise known in the art, e.g., air
(e.g., wind), water, gas, exhaust, and the like.
[0092] The accelerator 2504 may include any as described herein or
otherwise known in the art. For example, the accelerator 2504 may
include a structure that confines the flow of the fluid being
extracted, e.g., a nozzle, a diffuser, a cavity, a chamber, a
channel, a tube, or the like. In general, the accelerator 2504 may
be structurally configured to accelerate a fluid stream through the
extractor 2502, past the extractor 2502, or created by the
extractor 2502, thereby creating an accelerated fluid stream (e.g.,
the second fluid flow 2510) in the device 2500. The accelerator
2504 may thus condense a fluid stream directed toward the extractor
2502, through the extractor 2502, or in a flow path downstream of
the extractor 2502.
[0093] The device 2500 may be configured to prevent or limit
disturbances in the fluid flow created by the extractor 2502 within
the accelerator 2504. These disturbances may include blockage as
described herein. The disturbances (e.g., blockage) may be caused
by an extractor 2502 featuring rotors (e.g., rotor blades or the
like), where the rotors create a low velocity, high pressure region
that extends out from the center of a hub of the rotor to a surface
of the accelerator 2504. In this manner, the edges of the fluid
flow disposed at or near the surfaces of the accelerator 2504 may
form wakes, e.g., caused by high mass flow in a confined channel of
the accelerator 2504. These wakes created towards the outside/edges
of the accelerator 2504 may cause blockage. In some
extractors/accelerators, the blockage can be so significant that it
almost defeats the purpose of the accelerator 2504. It may thus be
desirous to include an extractor feature 2506 that reduces the mass
flow to the edges of the device 2500 near the surfaces of the
accelerator 2504.
[0094] The extractor feature 2506 may be structurally configured to
minimize blockage of the accelerated fluid stream (e.g., mitigate
non-power blockage in the fluid stream). The extractor feature 2506
may be present on, be part of, or otherwise be in mechanical or
fluid communication or cooperation with, one or more of the
extractor 2502 and the accelerator 2504. In an aspect, the
extractor feature 2506 is disposed on the accelerator 2504 (e.g.,
the extractor feature 2506 is basically a feature of the
accelerator 2504). In another aspect, the extractor feature 2506 is
disposed on the extractor 2502. The extractor feature 2506 may be
structurally configured to minimize individual extraction plane
flow effects by reducing individual plane solidity, e.g., thereby
minimizing blockage as described herein.
[0095] The extractor feature 2506 may include one or more of a
linear cascade, an oscillating foil, and an axial extractor.
[0096] In an aspect, the extractor feature 2506 includes a linear
cascade (e.g., an n-stage linear cascade). The linear cascade, for
example, may be the same or similar to any of those as described
herein, e.g., with reference to one or more of FIGS. 16, 19 and 20.
For example, in an aspect, the extractor feature 2506 includes a
linear cascade that includes two or more co-planar blades and a
stage solidity of less than about 20%.
[0097] In an aspect, the extractor feature 2506 includes an
oscillating foil (e.g., an n-stage oscillating foil). The
oscillating foil, for example, may be the same or similar to any of
those as described herein, e.g., with reference to one or more of
FIGS. 1-8. For example, in an aspect, the extractor feature 2506
includes an oscillating foil that includes two or more co-planar
foils and a stage solidity of less than about 20%.
[0098] In an aspect, the extractor feature 2506 includes an axial
extractor (e.g., an n-stage axial extractor). The axial extractor,
for example, may be the same or similar to any of those as
described herein, e.g., with reference to FIG. 11. For example, in
an aspect, the extractor feature 2506 includes an axial extractor
that includes two or more co-planar collapsible foils and a stage
solidity of less than 20%. The axial extractor may thus be a
feature of the extractor 2502, or may replace or supplement the
extractor 2502 of the device 2500.
[0099] The extractor feature 2506 may be structurally configured to
minimize blockage by minimizing flow effects engendered by power
extraction. The extractor feature 2506 may also or instead extract
power from a mono or bidirectional radial motion. In an aspect, the
mono or bidirectional radial motion includes a linear cascade. The
extractor feature 2506 may extract power from an axial motion. In
an aspect, power from the axial motion is extracted by one or more
of a piston and collapsible kite configuration or an electrostatic
system. Implementations may also or instead include an extractor
feature 2506 that extracts power from a combination of axial and
radial motion. In an aspect, the combination of axial and radial
motion is caused by one or more of an oscillating foil or an
unsteady aerodynamics configuration.
[0100] The extractor feature 2506 may be structurally configured to
extract power from a volume by utilizing multiple extraction
planes. One skilled in the art will recognize that an example of an
extraction plane is shown by the line that also represents the
extractor 2502 in the figure. The extractor feature 2506 may also
or instead be structurally configured to minimize flow effects by
minimizing a size of one or more extractor elements relative to
boundaries of the accelerator 2504 and other extraction planes. The
flow effects may include wakes.
[0101] In other words, the smaller the element (e.g., the extractor
feature 2506 or components thereof), the more localized the effect
the element has on the flow. In this manner, an improved device
2500 may include multiple small elements that create partitioned
wakes rather than large wakes that a single large element would
create. For example, for 1 m.sup.2 of surface area, it may be
advantageous to have ten 0.1 m.sup.2 surface areas rather than a
single 1 m.sup.2 area.
[0102] The extractor feature 2506 may be structurally configured to
reduce individual plane solidity to minimize individual extraction
plane flow effects. The extractor feature 2506 may also or instead
be structurally configured to limit flow effects to an outside of a
swept area by increasing a number and reducing a size of one or
more extractor elements. The extractor feature 2506 may also or
instead be structurally configured to counterbalance effects to an
outside of a swept area in at least one of a two-dimensional or
three-dimensional anhedral configuration thereby reducing one or
more of a tip leakage or a tip vortex expansion angle. In other
words, typically on a straight blade rotor, the fluid may "leak" up
the blade spinning of a tip vortex. Tilting the blade forward (such
as in an anhedral) may reduce the percentage of fluid that leaks up
the blade as the tilt counterbalances the centripetal force.
[0103] The extractor feature 2506 may also or instead be
structurally configured to minimize blockage between extractor
elements by changing a geometry of an extractor blade row (e.g.,
the space between the blades) from a nozzle to one or more of a
tube or diffuser configuration that utilizes an axial offset in one
or more of a spiral or angled configuration.
[0104] The extractor feature 2506 may also or instead include a
brim on the accelerator 2504, drill throughs, double annular
shells, or the like.
[0105] FIG. 26 shows a device for fluid power generation.
Specifically, this figure shows a device 2600 having a plurality of
accelerator-extractor pairs in the form of turbines 2602 disposed
in channels 2604.
[0106] The above systems, devices, methods, processes, and the like
may be realized in hardware, software, or any combination of these
suitable for a particular application. The hardware may include a
general-purpose computer and/or dedicated computing device. This
includes realization in one or more microprocessors,
microcontrollers, embedded microcontrollers, programmable digital
signal processors or other programmable devices or processing
circuitry, along with internal and/or external memory. This may
also, or instead, include one or more application specific
integrated circuits, programmable gate arrays, programmable array
logic components, or any other device or devices that may be
configured to process electronic signals. It will further be
appreciated that a realization of the processes or devices
described above may include computer-executable code created using
a structured programming language such as C, an object oriented
programming language such as C++, or any other high-level or
low-level programming language (including assembly languages,
hardware description languages, and database programming languages
and technologies) that may be stored, compiled or interpreted to
run on one of the above devices, as well as heterogeneous
combinations of processors, processor architectures, or
combinations of different hardware and software. In another aspect,
the methods may be embodied in systems that perform the steps
thereof, and may be distributed across devices in a number of ways.
At the same time, processing may be distributed across devices such
as the various systems described above, or all of the functionality
may be integrated into a dedicated, standalone device or other
hardware. In another aspect, means for performing the steps
associated with the processes described above may include any of
the hardware and/or software described above. All such permutations
and combinations are intended to fall within the scope of the
present disclosure.
[0107] Embodiments disclosed herein may include computer program
products comprising computer-executable code or computer-usable
code that, when executing on one or more computing devices,
performs any and/or all of the steps thereof. The code may be
stored in a non-transitory fashion in a computer memory, which may
be a memory from which the program executes (such as random access
memory associated with a processor), or a storage device such as a
disk drive, flash memory or any other optical, electromagnetic,
magnetic, infrared or other device or combination of devices. In
another aspect, any of the systems and methods described above may
be embodied in any suitable transmission or propagation medium
carrying computer-executable code and/or any inputs or outputs from
same.
[0108] It will be appreciated that the devices, systems, and
methods described above are set forth by way of example and not of
limitation. Absent an explicit indication to the contrary, the
disclosed steps may be modified, supplemented, omitted, and/or
re-ordered without departing from the scope of this disclosure.
Numerous variations, additions, omissions, and other modifications
will be apparent to one of ordinary skill in the art. In addition,
the order or presentation of method steps in the description and
drawings above is not intended to require this order of performing
the recited steps unless a particular order is expressly required
or otherwise clear from the context.
[0109] The method steps of the implementations described herein are
intended to include any suitable method of causing such method
steps to be performed, consistent with the patentability of the
following claims, unless a different meaning is expressly provided
or otherwise clear from the context. So for example performing the
step of X includes any suitable method for causing another party
such as a remote user, a remote processing resource (e.g., a server
or cloud computer) or a machine to perform the step of X.
Similarly, performing steps X, Y and Z may include any method of
directing or controlling any combination of such other individuals
or resources to perform steps X, Y and Z to obtain the benefit of
such steps. Thus method steps of the implementations described
herein are intended to include any suitable method of causing one
or more other parties or entities to perform the steps, consistent
with the patentability of the following claims, unless a different
meaning is expressly provided or otherwise clear from the context.
Such parties or entities need not be under the direction or control
of any other party or entity, and need not be located within a
particular jurisdiction.
[0110] It should further be appreciated that the methods above are
provided by way of example. Absent an explicit indication to the
contrary, the disclosed steps may be modified, supplemented,
omitted, and/or re-ordered without departing from the scope of this
disclosure.
[0111] It will be appreciated that the methods and systems
described above are set forth by way of example and not of
limitation. Numerous variations, additions, omissions, and other
modifications will be apparent to one of ordinary skill in the art.
In addition, the order or presentation of method steps in the
description and drawings above is not intended to require this
order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, while
particular embodiments have been shown and described, it will be
apparent to those skilled in the art that various changes and
modifications in form and details may be made therein without
departing from the spirit and scope of this disclosure and are
intended to form a part of the invention as defined by the
following claims, which are to be interpreted in the broadest sense
allowable by law.
* * * * *