U.S. patent application number 13/128563 was filed with the patent office on 2012-04-26 for fluid directing system for turbines.
Invention is credited to Frederick Churchill, Ion Paraschivoiu, Octavian Trifu.
Application Number | 20120099977 13/128563 |
Document ID | / |
Family ID | 42152440 |
Filed Date | 2012-04-26 |
United States Patent
Application |
20120099977 |
Kind Code |
A1 |
Churchill; Frederick ; et
al. |
April 26, 2012 |
FLUID DIRECTING SYSTEM FOR TURBINES
Abstract
A directing system for directing fluid entering an axial flow
turbine along an inlet flow direction. The turbine includes a
plurality of turbine blades. The directing system includes a base
structure, a plurality of directing segments attached to the base
structure, downstream of the base structure, and a directing
segment adjustment system for adjustably positioning the directing
segments between a retracted configuration and a deployed
configuration. The directing segments, in the deployed
configuration, extend beyond the base structure in a direction
transversal to the inlet flow direction and deflect the fluid
towards an outer circumference of the plurality of turbine blades
corresponding to a higher torque area of the blades. A directing
system for directing fluid entering a cross-flow turbine is also
disclosed. In the cross-flow turbine, the fluid is directed towards
a centerline of the rotor of the turbine, which is a high torque
area of the turbine blades.
Inventors: |
Churchill; Frederick;
(Montreal, CA) ; Paraschivoiu; Ion; (Ville
Mont-Royal, CA) ; Trifu; Octavian; (Laval,
CA) |
Family ID: |
42152440 |
Appl. No.: |
13/128563 |
Filed: |
November 9, 2009 |
PCT Filed: |
November 9, 2009 |
PCT NO: |
PCT/CA2009/001641 |
371 Date: |
December 30, 2011 |
Current U.S.
Class: |
415/185 |
Current CPC
Class: |
F03B 15/08 20130101;
Y02E 10/223 20130101; F05B 2240/244 20130101; F05B 2270/32
20130101; Y02E 10/20 20130101; Y02E 10/28 20130101; F05B 2240/211
20130101; F05B 2240/217 20130101; Y02E 10/226 20130101; F05B
2240/121 20130101; F05B 2270/1014 20130101; F03B 3/183 20130101;
F03B 17/061 20130101; Y02E 10/72 20130101; F03B 17/062 20130101;
F05B 2210/16 20130101; F05B 2240/221 20130101; Y02E 10/721
20130101; F03D 1/04 20130101 |
Class at
Publication: |
415/185 |
International
Class: |
F01D 9/02 20060101
F01D009/02; F01D 1/04 20060101 F01D001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2008 |
CA |
2643567 |
Claims
1. A directing system for directing fluid entering an axial flow
turbine along an inlet flow direction, said turbine comprising a
plurality of turbine blades, said directing system comprising: a
base structure; a plurality of directing segments attached to the
base structure; a directing segment adjustment system for
adjustably positioning the directing segments between: a retracted
configuration; and a deployed configuration; and an outer shroud
surrounding a circumference of the turbine blades, wherein the
directing segments, in the deployed configuration, extend beyond
the base structure in a direction transversal to the inlet flow
direction and deflect the fluid towards an outer circumference of
the plurality of turbine blades.
2. The directing system as described in claim 1, wherein the base
structure is fixed to a central rotating shaft of the turbine.
3. The directing system as described in claim 2, wherein the
plurality of directing segments are overlapping segments radially
positioned around the base structure, and the directing segment
adjustment system comprises: a set of tension rods holding the
directing segments in place; and a motorized threaded nut system
traveling along a threaded portion of the central shaft and
displacing the base structure in relation to an axial displacement
of the directing segments.
4. The directing system as described in claim 2, wherein the
turbine blades are housed between an inner annular shroud and the
outer shroud, the base structure extends radially up to the inner
annular shroud and the directing segments extend to a maximum
diameter corresponding to a diameter of the outer shroud.
5. The directing system as described in claim 1, wherein a diameter
of the base structure is at least 0.3 times a diameter of a rotor
of the turbine.
6. The directing system as described in claim 1, further comprising
a compressor fan positioned upstream of the base structure and
increasing velocity of the fluid entering the turbine.
7. The directing system as described in claim 1, wherein the
directing segment adjustment system comprises a controller and the
directing system further comprises a fluid velocity measurement
system located upstream of the base structure and producing a
signal indicative of fluid velocity entering the turbine, and
wherein the controller adjusts the directing segment adjustment
system based on the signal indicative of fluid velocity entering
the turbine.
8. A directing system for directing fluid entering a cross-flow
turbine along an inlet flow direction, said turbine comprising a
rotor, said rotor comprising a plurality of turbine blades, said
directing system comprising: an inlet directing fluid towards the
turbine; a plurality of directing segments attached to the inlet;
and a directing segment adjustment system for adjustably
positioning the directing segments between: a retracted
configuration; and a deployed configuration, wherein the directing
segments, in the deployed configuration, extend beyond the inlet in
a direction transversal to the inlet flow direction and direct the
fluid towards a centerline of a rotor of the turbine.
9. The directing system as described in claim 8, wherein the
plurality of directing segments are two inlet side deflectors
pivotably attached to the inlet and the directing segment
adjustment system comprises a pair of actuators for pivoting the
two side deflectors with respect to the inlet.
10. The directing system as described in claim 9, further
comprising an outlet directing fluid away from the turbine, a
second set of two outlet side deflectors pivotably attached to the
outlet and a second pair of actuators for pivoting the second set
of the two outlet side deflectors with respect to the outlet.
11. The directing system as described in claim 8, further
comprising a set of adjustably positionable side baffle plates
concentrically positioned within an outer circumference of the
rotor of the turbine.
12. The directing system as described in claim 11, further
comprising a set of baffle plate actuators for adjustably
positioning the side baffle plates based on a corresponding
configuration of the inlet side deflectors.
13. The directing system as described in claim 12, wherein the set
of adjustable baffle plates are supported by a set of support bars
attached to a shroud surrounding the turbine.
14. The directing system as described in claim 8, wherein the
directing segment adjustment system comprises a controller and the
directing system further comprises a fluid velocity measurement
system located upstream of the inlet and producing a signal
indicative of fluid velocity entering the turbine, and wherein the
controller adjusts the directing segment adjustment system based on
the signal indicative of fluid velocity entering the turbine.
15. The directing system as described in claim 1, wherein the base
structure is fixed to a fixed shaft supported by a turbine frame.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to both wind and
water turbines. More specifically, the present invention relates to
a fluid directing system for directing a fluid entering an axial
flow or cross-flow turbine.
BACKGROUND OF THE INVENTION
[0002] Wind turbines are generally rated at the wind speed at which
they will produce the rated power or essentially the maximum power
rating of the generator. At lower wind velocities the turbine will
produce only a fraction of the rated power.
[0003] Low winds contain less energy than high winds so
automatically they produce less useful energy. The rotor efficiency
or percentage of energy converted from the wind into useful torque
also drops as the Reynolds number of the blades decreases at low
wind speeds. There is a definite need for a rotor design that could
increase the power obtained from air streams at all speeds and most
particularly for velocities below the turbine rated speed. The
additional power generated by the blades once the rated velocity is
exceeded is lost.
[0004] The fact that wind speeds vary all the time is a problem for
windmill designers and windmill operators. Existing wind turbines
designs offer little control over immediate wind speed variations.
Most existing turbines are equipped with a hydraulic driven blade
pitch adjustment. These systems adjust the blade pitch to average
wind velocity as calculated over a time period and not to the
instantaneous wind speed.
[0005] At all wind speeds, and particularly at high wind speeds,
wind gusts cause considerable operating problems. The energy in the
gust will rapidly increase the rotor and generator rotational
speed. This can cause voltage fluctuations in the power produced
that must be removed electrically. In order to limit the rotational
speed, the blade pitch can be adjusted but the blades are massive
and the hydraulically driven pitch adjustment is not rapid.
Consequently, the brake is often applied to limit the increase in
rotor speed.
[0006] Existing turbine designs treat all the swept area of the
rotor as equal. Although the wind energy available to the blades is
constant over the entire swept area most of the energy is generated
in the high torque zone that corresponds to the area closer to the
tips of the blade. The energy of the wind traveling close to the
center shaft or the core of the swept area is essentially
wasted.
[0007] A technology that addresses the difficulties above would
greatly improve turbine efficiency, improve the electrical
stability of the production and decrease the production costs for
electricity.
[0008] There is thus presently a need for a system to increase the
energy produced by a turbine at all operating wind or fluid
speeds.
[0009] There is also a need for a system that divides the swept
area of a rotor into high torque and low torque sectors.
[0010] There is also a need for a system to increase and control
the wind velocity by adjusting the size of the swept area. This is
achieved by blocking or sectoring part of the swept area.
[0011] There is also a need for a system to increase the velocity
pressure at the face of the blades that is non-sectored, and
install an outer shroud to prevent the increased velocity pressure
from spilling over the edges of the blades and an inner shroud to
prevent air bleeding into the low torque zone of the rotor.
[0012] There is also a need for a system to control the wind
velocity through the non-sectored area of the rotor blades.
[0013] There is also a need for a system to increase the wind
velocities at the blades by rotor-sectoring to maximize velocity
pressure, blade Reynolds number and the rotor efficiency
coefficient.
[0014] There is also a need for a system to establish an effective
closed loop control based on wind speed and the dimensions of the
sectored swept area that maintains constant the rotational speed of
the rotor and electrical generator.
[0015] There is also a need for a system to direct the airflow at a
maximum wind pressure to the outermost radius of the rotor whereby
maximizing the torque produced per unit of air mass.
[0016] There is also a need for a system to develop a design of
rotor sectoring that can be retrofitted to existing turbines.
SUMMARY OF THE INVENTION
[0017] An object of the present invention is to provide a directing
system that satisfies at least one of the above-mentioned
needs.
[0018] According to the present invention, there is provided a
directing system for directing fluid entering an axial flow turbine
along an inlet flow direction, the turbine comprising a plurality
of turbine blades, the directing system comprising: [0019] a base
structure; [0020] a plurality of directing segments attached to the
base structure; [0021] a directing segment adjustment system for
adjustably positioning the directing segments between: [0022] a
retracted configuration; and [0023] a deployed configuration;
[0024] and [0025] a shroud surrounding a circumference of the
turbine blades, wherein the directing segments, in the deployed
configuration, extend beyond the base structure in a direction
transversal to the inlet flow direction and deflect the fluid
towards an outer circumference of the plurality of turbine
blades.
[0026] According to the present invention, there is also provided a
directing system for directing fluid entering a cross-flow turbine
along an inlet flow direction, the turbine comprising a rotor, the
rotor comprising a plurality of turbine blades, the directing
system comprising: [0027] an inlet directing fluid towards the
turbine; [0028] a plurality of directing segments attached to the
inlet; and [0029] a directing segment adjustment system for
adjustably positioning the directing segments between: [0030] a
retracted configuration; and [0031] a deployed configuration,
wherein the directing segments, in the deployed configuration,
extend beyond the inlet in a direction transversal to the inlet
flow direction and deflect the fluid towards a centerline of a
rotor of the turbine.
[0032] The present invention provides an apparatus, which is able
to displace part of a fluid stream just prior to reaching the
turbine rotor. This displacement moves the fluid from a section of
the swept area producing low torque to a section producing higher
torque. The two fluid volumes are combined to increase the fluid
velocity and velocity pressure over the high torque area. This
principle is common to all axial flow and cross-flow turbines.
[0033] In the case of axial flow turbines, the apparatus consists
of a central conically or semi-circular shaped cone that directs
the fluid stream from the center towards the periphery of the
rotor. The cone retracts or deploys overlapping wall segments
creating an annular shaped channel for the fluid stream to pass
through the rotor blades. The exterior of the turbine is shrouded
to prevent the velocity pressure increase from spilling over the
tips of the turbine blades. In its retracted position, the
sectoring cone occupies preferably between 50 and 75% of the total
swept area of the rotor.
[0034] Located behind the walls of the sectoring cone, where it is
protected from the fluid stream, a mechanism is installed that
permits to expand or deploy overlapping wall segments. As the
segments are expanded, the sectored or blocked area of the rotor is
increased to 100%. A sectoring of 90 to 99% of the available swept
area is applied when the nominal fluid velocity is low, whereas a
sectoring of 0 to 10% of the available swept area corresponds to a
high nominal fluid speed.
[0035] In the case of cross-flow turbines, aerodynamic side
deflectors are installed that can be extended or rotated into the
fluid stream. The side deflectors are attached to the turbine
shrouds that serve as a housing in front of the upstream and
downstream faces of the rotor. The shrouds or sidewalls are
required to prevent the increase in velocity pressure from spilling
around the edges of the rotor blades.
[0036] Actuators attached to the turbine frame push against the
deflectors that rotate into the fluid stream and decrease the width
of the opening. As the deflectors advance, the low torque sectors
of the rotor decrease and the fluid stream is concentrated in the
high torque sector. When the deflectors are fully extended the high
torque area receives almost all the fluid whereas the low torque
sector receives very little or no fluid.
[0037] Inside the vertical axis rotor itself are located two sets
of straight vertical side plates or inner walls. These side plates
move back and forth, synchronized with the displacement of the side
deflectors to create a more defined channel with less turbulence.
These side plates necessitate the use of a true H-type vertical
rotor configuration whereby the blades are supported close to their
midpoints and with little cross bracing.
[0038] For both the axial and cross-flow turbines, the velocity
pressure of the fluid stream over the high torque area is increased
providing considerable more power. Although the swept area of the
rotors has been decreased, the increase in fluid velocity or
velocity pressure provides a much greater contribution to energy
production. The adjustment of the swept area also controls the
fluid stream velocity to the blades providing maximum efficiency
for the rotor at all nominal fluid speeds. The control of the fluid
stream speed in turn provides for steady rotor rotational speeds
for more stable and efficient electrical power generation.
BRIEF DESCRIPTION OF DRAWINGS
[0039] These and other objects and advantages of the invention will
become apparent upon reading the detailed description and upon
referring to the drawings in which:
[0040] FIG. 1 is a schematic view of the zones (sectors) of low and
high torques on the swept area of an axial flow turbine.
[0041] FIG. 2 is a side cut view of a directing system according to
a preferred embodiment of the present invention for a shrouded
axial flow turbine.
[0042] FIG. 3 is a side cut view of a directing system according to
another preferred embodiment of the present invention for an
augmented axial flow turbine.
[0043] FIG. 4 is a perspective view of a one-piece directing system
according to another preferred embodiment of the present invention,
with segments deployed.
[0044] FIG. 5 is a perspective view of the directing system shown
in FIG. 4, with segments retracted.
[0045] FIGS. 6A to 6E are three perspective interior views and two
detailed views respectively of the directing system shown in FIGS.
4 and 5 in fully deployed, 50% deployed and retracted
configurations respectively.
[0046] FIG. 7 is a perspective view of a directing system according
to another preferred embodiment of the present invention, equipped
with a variable speed compressor fan.
[0047] FIG. 8 is a perspective view of a two-piece directing system
according to another preferred embodiment of the present invention,
with segments deployed.
[0048] FIG. 9 is a perspective view of a two-piece directing system
according to another preferred embodiment of the present invention,
with segments retracted.
[0049] FIGS. 10A to 10C are perspective interior views of the
directing system shown in FIGS. 8 and 9 in fully deployed, 50%
deployed and retracted configurations respectively.
[0050] FIG. 11 is a perspective view of a two-piece directing
system according to another preferred embodiment of the present
invention, equipped with a variable speed compressor fan.
[0051] FIG. 12 is a graph of power vs. sectoring ratio at three
nominal wind speeds for a shrouded axial flow turbine with a
directing system according to a preferred embodiment of the present
invention.
[0052] FIG. 13 is a graph of chord and twist angle distribution
along the blade used for a simulation of operation of a standard
twisted horizontal axis wind turbine rotor.
[0053] FIG. 14 is a schematic view illustrating zones (sectors) of
low and high torques on the swept area of a cross-flow turbine
[0054] FIG. 15 is a graph illustrating the azimuthal variation of
tangential force (FT) of a generic cross-flow turbine
[0055] FIG. 16 is a top cut view of a directing system according to
a preferred embodiment of the present invention in use with a
shrouded cross-flow turbine.
[0056] FIG. 17 is a top cut view of a directing system according to
another preferred embodiment of the present invention in use with
an augmented cross-flow turbine.
[0057] FIG. 18 is a perspective view of a directing system
according to another preferred embodiment of the present
invention.
[0058] FIG. 19 is a graph of power vs. sectoring ratio at three
nominal wind speeds for a shrouded axial flow turbine with a
directing system according to a preferred embodiment of the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0059] Although the invention is described in terms of specific
embodiments, it is to be understood that the embodiments described
herein are by way of example only and that the scope of the
invention is not intended to be limited thereby.
[0060] As shown in FIGS. 2 to 11 and as better shown in FIGS. 4 and
5, according to the present invention, there is provided a
directing system 1000 for directing fluid entering an axial flow
turbine 1002 along an inlet flow direction. The turbine 1002
comprises a plurality of turbine blades 1004. The directing system
1000 includes a central base structure 1006, and a plurality of
directing segments 1008 attached to the central base structure
1006. The directing system also includes a directing segment
adjustment system 1010 for adjustably positioning the directing
segments 1008 between a retracted configuration (shown in FIG. 5)
and a deployed configuration (shown in FIG. 4). The directing
segments 1008, in the deployed configuration, extend beyond the
base structure 1006 in a direction transversal to the inlet flow
direction and deflect the fluid towards an outer circumference of
the plurality of turbine blades 1004.
[0061] Preferably, the base structure 1006 is fixed to a central
rotating shaft of the turbine 1002.
[0062] Preferably, as better shown in FIGS. 6A to 6C, the plurality
of directing segments 1008 are overlapping segments radially
positioned around the base structure 1006. The directing segment
adjustment system 1010 comprises a set of tension rods 1012 holding
the directing segments 1008 in place and a motorized threaded nut
system 1014 traveling along a threaded portion of the central
rotating shaft and controlling pressure being applied on the
tension rods 1012.
[0063] Preferably, as shown in FIG. 5, the turbine blades 1004 are
housed between an inner annular shroud 1016 and an outer annular
shroud 1018. The base structure 1006 can extend radially up to the
inner annular shroud 1016 and the directing segments 1008 extend to
a maximum diameter corresponding to a diameter of the outer annular
shroud 1018.
[0064] Preferably, a diameter of the base structure is at least 0.3
times a diameter of a rotor of the turbine.
[0065] Preferably, as shown in FIG. 7, the directing system 1000
further includes a compressor fan 1020 positioned upstream of the
base structure 1006 and increasing velocity of the fluid entering
the turbine.
[0066] Preferably, the directing segment adjustment system
comprises a controller and the directing system further comprises a
fluid velocity measurement system located upstream of the base
structure. The measurement system produces a signal indicative of
fluid velocity entering the turbine. The controller then adjusts
the directing segment adjustment system based on the signal
indicative of fluid velocity entering the turbine.
[0067] According to the present invention, there is also provided a
rotor-sectoring apparatus for axial flow turbines for use with at
least one turbine to increase the velocity pressure of the air
stream contacting the blades of the wind turbine, the
rotor-sectoring apparatus comprising: [0068] (a) an inner and outer
turbine shrouds constituting a shrouded annular turbine section,
the section comprising an entrance and an exit said entry having a
nominal diameter equal to said exit; [0069] (b) an entrance and
exit adapters to said shrouded annular section with the entrance
and exit diameters being slightly larger than said shrouded section
to reduce the loss of velocity pressure as the wind stream enters
and exits said shrouded section; [0070] (c) an aerodynamically
shaped sectoring cone positioned upstream of the rotor having
overlapping walls that permit the diameter of the base of said
sectoring cone to increase and decrease while retaining its
aerodynamic configuration and same shape; [0071] (d) a sectoring
cone positioned on the downwind side of the rotor blades to
maximize the velocity pressure recovery after the rotor blades;
[0072] (e) the adjustable upstream sectoring cone having a maximum
diameter equal to the diameter of the outer shroud and minimum
diameter equal to the diameter of the inner shroud; [0073] (f) a
retracting mechanism that retracts and deploys the overlapping cone
segments; [0074] (g) a set of tension rods that hold the
overlapping segments in place and transmit a change of height of
the cone into a change in the diameter of its base; [0075] (h) a
motorized threaded nut that travels back and forth along a threaded
portion of the rotor shaft to adjust the diameter of the sectoring
cone by applying or relieving pressure to the segment tension rod
holding disk; [0076] (i) a wind velocity measurement located
upstream of the sectoring cone and that transmits a continuous
signal for adjusting diameter of the sectoring cone; [0077] (j) an
electronic controller programmed to read the wind speed from the
wind velocity instrument and adjust the position of the motorized
nut to control the wind speed at the face of the said rotor blades;
and [0078] (k) a compressor fan with an adjustable speed drive that
fits over the end of the rotor shaft and serves to increase the
velocity pressure at the face of the said rotor blades.
[0079] Preferably, the shrouded wind turbine rotor has a minimum of
three blades and a maximum of 50 blades all having the same nominal
diameter as the shrouded section.
[0080] Preferably, the rotor-sectoring device produces an annular
shaped channel at the face of the rotor blades of variable
dimensions by increasing or decreasing the diameter of the
sectoring device.
[0081] Preferably, the rotor-sectoring apparatus is capable of
adjusting its diameter between 0.30 and 1.0 times the diameter of
the turbine rotor.
[0082] Preferably, the sectoring cone is of such dimensions that it
can be mounted on the shaft of the turbine rotor in order to rotate
with the turbine into the wind.
[0083] Preferably, the rotor-sectioning cone has an aerodynamic
form that maximizes the wind pressure at the face of the rotor
blades.
[0084] In another embodiment of the present invention, the
rotor-sectioning cone preferably uses the rotational speed of the
rotor shaft to deploy the overlapping segments.
[0085] Preferably, the rotor-sectioning cone increases its diameter
without increasing the distance between the base of the cone and
the rotor.
[0086] Preferably, the rotor-sectioning device directs the air
stream to the optimum section of the rotor blades to develop the
maximum torque per unit of air volume at all wind speeds.
[0087] Preferably, the rotor-sectioning cone can increase the power
generated significantly by a conventional HAWT or axial flow
turbine at evaluated wind speeds of 4.0, 7.0 and 12.0 m/s.
[0088] Preferably, the rotor-sectioning apparatus can increase the
power output of existing HAWT wind turbines by retrofitting the
apparatus to the existing rotor or turbine.
[0089] Preferably, the rotor-sectioning apparatus performs
satisfactorily with non-augmented or augmented axial flow wind
turbines.
[0090] Preferably, the rotor-sectioning apparatus incorporates a
motorized fan on the end of the rotor shaft to increase the
velocity pressure at the face of the rotor blades.
[0091] The aforesaid and other objectives of the present invention
are realized by generally providing a rotor-sectoring apparatus for
use with a wind turbine to increase the velocity pressure of the
air contacting the blades. The rotor-sectoring apparatus comprises
shrouded rotor with a curve-shaped adapter at the entrance and
conical or curved adapter at the exit, a sectoring cone with
overlapping segments supported by the shaft of the rotor, a cone
deployment mechanism employing tension arms located behind the
sectoring cone segments, a series of overlapping outer segments
with outside radius when extended essentially the same as the
radius of the turbine rotor, an actuator mounted on the rotor shaft
to deploy the segments in synchronous fashion, a wind measurement
device located upstream of the rotor-sectoring apparatus entrance,
and an actuator or series of actuators which respond to a
controller programmed to hold the wind speed constant by adjusting
the deployment of the cone segments.
[0092] The idea behind the concept consists in using an adequate
flow control system to direct the incoming air stream towards those
zones of the rotor swept area that are the most efficient in terms
of energy conversion. Certainly, this concept may be applied to
conventional non-augmented wind turbines as well as to augmented
wind turbines which are operated inside a wind augmenting system. A
wind augmentation system ensures an increase in the velocity
pressure of the wind in front of the turbine rotor. The increase in
velocity pressure may be small of the order of fractions of inches
of water or may be quite large of the order of several feet of
water and requiring the application of a large
convergent-divergent.
[0093] In the case of a HAWT (Horizontal Axis Wind Turbine)
turbine, the sectoring can be done with the aid of a cone-like or
semi-circular body, with variable geometry capability, installed in
front of the rotor. The cone will direct the air flux toward the
high torque zone and will prevent it to pass through its low
efficiency central zone, while also accelerating the air stream.
Since the flow regime upstream of the rotor, even in an augmenting
system, is basically a subsonic incompressible one (V<100 m/s),
the body placed in front of the rotor for sectoring purposes
preferably has a semi-spherical shape.
[0094] In the case of a HAWT rotor (propeller type), the
application of the concept described here aims at directing the air
flux toward its periphery (zone of high torque 110) as shown in
FIG. 1, and avoid passing it through the central zone of the rotor
where, due to the small distance from the rotation axis the blades
have reduced tangential speed, thus poor aerodynamic efficiency
(low torque zone 100). The construction principle of the rotor
swept area "sectoring" concept is illustrated in FIG. 2 for the
case of a shrouded HAWT (including a shroud inlet 210, turbine
shroud 200 and shroud outlet 220) and FIG. 3 for the case of a HAWT
employing an augmented wind energy system (including a turbine 300,
convergent inlet 310, a diffuser 320, upwind cone 312 adjustable
between wrapped 340 and deployed 360 configurations, a strut 322, a
turbine section 314, and an adjustable downwind cone 324).
[0095] With shrouded turbines, the entrance and exit adapters are
located at the ends of the shrouds or turbine section and in the
case of augmented turbines after the convergent and before the
diffuser. Both adapters are designed specially to reduce the
entrance and exit losses. The length, width and shape of the
entrance and exit adapters are designed using standard air handling
design practices and do not increase the velocity pressure of
either the incoming or outgoing air stream. The inside diameter of
both is essentially the diameter of the shroud. The entrance and
exit areas are preferably between 1.2 and 1.7 times the rotor
area.
[0096] The shroud has essentially the same diameter as the rotor to
avoid air stream bypassing the rotor blades. As the air stream
enters the shroud the sectoring cone reduces progressively the
swept area and this increases the velocity pressure upstream of the
blades. The role of the shroud is to prevent the increase in
velocity pressure from spilling around the blade tips and uniform
the wind direction upstream and downstream of the blades. The
length of the shroud is a function of the velocity pressure
upstream of the blades. At higher velocities the shroud needs to be
longer than at lower velocities, as the velocity pressure is
higher.
[0097] The parameter used to compare the relative amounts of the
swept area that is sectored is the sectoring ratio or SR. SR is
defined as the fraction of the non-swept area (open flow area) of
the rotor blades as a fraction of the total swept area of the
rotor.
[0098] In order to minimize the travel of the sectoring cone
tension rods and the amount of overlap of the segments, the
retracted position of the cone will stop once the determined high
torque zone is completely open to the air stream. As a general
rule, the length of travel of the tension rods corresponds to a SR
of 0.70 to 0.0. At a SR of 0.0 the rotor swept area is fully
sectored and airflow is stopped, at 0.50 the sectored area is equal
to 50% of the rotor swept area.
[0099] In order to simplify the deployment mechanism the sectoring
cone can be built in two-pieces instead of one-piece. The head of
the cone is fixed and only the base of the cone deploys. This
shortens the length of the cone arms and provides a more precise
control of the SR.
[0100] It has been determined that the velocity pressure increases
as the SR decreases or rather as the cone overlapping segments open
or deploy. Deployment of the cone segments is not a problem even
for large diameter rotors as the diameter of the fixed cone
increases with the diameter of the rotor. The centrifugal force
will also assure that the tension rods are always under
tension.
[0101] The force required to retract the segments is obtained by
installing a motorized nut on a threaded section of the rotor
shaft. As the nut turns it will increase the overall height of the
cone. The circular collecting plate at the apex of the cone that
holds the tension arms in place will be raised or lowered through
the displacement of the motorized nut along the threaded shaft.
[0102] As the base of the cone is fixed the tension applied to the
tension rods that hold the segments in place will force a decrease
in the area of the base of the sectoring cone. This in turn adjusts
the sectoring ratio of the rotor. As the position of the base of
the sectoring cone is fixed the distance between the edges of the
overlapping segments and the rotor blades remains constant at all
values of SR.
[0103] In a further embodiment, the sectoring cone design rather
than being one-piece can be designed as two unequal pieces as shown
in FIGS. 8 to 11. The first piece is immovable, has a fixed
diameter and is mounted on the end of the rotor shaft or to the
frame supporting the turbine rotor. The second piece is a series of
deployable overlapping segments and is installed in the wind shadow
of the first piece. The form of the deployable segments is
basically the same form as the lower section of the first half. As
a result the deployable segments when fully retracted are protected
or covered from the air stream.
[0104] As the segments deploy the diameter of the cone increases
and the extremities of the segments approach the rotor blades. The
most outer edge of the segments may be rounded or streamlined in
the direction of the airflow in order to reduce turbulence at the
blades. As the segments deploy the distance between the outer edge
and the face of the blades remains constant. A motorized nut
located on the shaft of the sectoring cone pushes the head of the
cone farther away from the blades. The pressure of the oncoming
wind will always push the cone towards the blades. When fully
deployed, the segments will reduce the sectored area up to 100% of
the total swept area of the rotor.
[0105] In the cases of one-piece, two-piece or multiple-piece
assemblies of the sectoring cone, the actuators, which deploy the
segments, may be pneumatic, hydraulic or electric. As they deploy,
the segments slide along tracks designed to withstand the forces
exerted by the incoming wind. As the sectoring cone is normally
circular and fixed to the rotor shaft it creates an annular shaped
sectored area, which grows in diameter as the segments deploy. This
annular configuration is important as it directs the air stream
equally to the outermost radius of the blades and it is an
efficient form for increasing the velocity pressure by decreasing
the swept area and this with minimal friction losses.
[0106] In a further embodiment the sectoring device may be attached
to the shaft of an existing three-blade rotor. This will require
the addition of an outer shroud to prevent the loss of the
additional wind pressure generated by the sectoring device spilling
over the tips of the blades. A second inner shroud is added to
prevent the increase in velocity pressure from entering the low
torque zone centered on the rotor shaft. This device provides the
same benefits: it increases the total energy of the wind through
the blades, it directs the air stream to the optimum area of the
high torque zone and it allows for a precise control of the
velocity through the blades.
[0107] In a further embodiment a sectoring device is added to the
downstream face of the rotor. This reduces the frictional losses,
turbulence and loss of velocity pressure downstream of the rotor
blades.
[0108] The upstream air speed measurement consists of an instrument
mounted on an extension to the rotor shaft. It is wireless and
mounted on a bearing to avoid rotating with the shaft. As wind
speeds of 12 m/s are common an extension of 3 meters will permit a
reaction time for the controller and actuators responsible for
deploying the outer segments of the order of 0.25 seconds.
[0109] As a preferred embodiment, adjustable liners may be
installed on the inner rim of the rotor and deploy at the same
vertical speed as the cone segments. The role of these inner liners
is simply to reduce turbulence as the air flows between the blades
close to the inner rim. The inner segments are not required to
section the rotor. They are installed on the inner rim to reduce
the friction losses as the wind passes between the rotor blades.
Essentially both the inner liners and sectoring cone segments
deploy together to provide a more even channel flow through and
after the blades.
[0110] In another preferred embodiment a motorized variable speed
compressor fan is attached to the rotor shaft above the sectoring
cone. The compressor fan accelerates the speed and volume of the
air stream being displaced from the low torque zone to the high
torque zone.
[0111] The turbines can be augmented or non-augmented although the
results with augmented turbines are more impressive given the
higher wind speeds. The rotors of existing turbines can be replaced
by this new technology to improve their performance. Otherwise this
technology is implemented in the manufacture of new sectored and
shrouded air and water turbines. By the principle of dynamic
similarity, the results obtained when air is the fluid in motion is
also applicable when water is the fluid in motion.
[0112] FIGS. 2 and 3 show the principal sections of the
rotor-sectoring device, which include firstly the axial flow
turbine rotor, the rotor blades and their swept area and secondly
the sectoring cone apparatus. FIGS. 4 and 5 illustrate the
sectoring cone outer shroud (1), the rotor blades mounted on a
blade shaft (2) the sectoring cone inner shroud (3), the rotor
spokes (4) the rotor hub (5) and the turbine drive shaft (6). In
illustrating the sectoring cone, FIGS. 4 and 5 show the adjustable
outer edge of the overlapping segments forming the body of the cone
(7), the segment tension rod retaining disc (8) and the shaft of
the sectoring apparatus (9).
[0113] FIGS. 4 and 5 also show the non-dimensional references of
the variable outside radius of the sectoring cone (R3), the outside
radius of the rotor blades (R2) and the inside radius of the rotor
blades (R1). FIG. 2 shows the non-dimensional reference to the
adjustable variable outside radius of the sectoring cone (R3). The
reference to the adjustable edge of the overlapping segments (7)
and the reference (R3) to the adjustable outside radius of the
sectoring cone is synonymous.
[0114] FIGS. 6A to 6E show the deployment mechanism of the
sectoring cone that includes curved tension rods that hold the
overlapping segments in position (10), the outer rim of the
sectoring cone (11), the spokes of the sectoring mechanism (12) and
the sliding connection that permits the overlapping segments to
deploy and retract by allowing the slip connection to travel along
the spokes of the sectoring mechanism (13).
[0115] FIG. 7 illustrates a sectored HAWT with a motorized drive
(14) for a compressor fan (15) mounted on the end of the rotor
shaft.
[0116] FIG. 8 illustrates a fully deployed two-piece sectoring
apparatus. The overlapping segments (7) are deployed from the fixed
upper cone (8) and the sectoring cone shaft (9).
[0117] FIG. 9 illustrates a two-piece sectoring device with the
segments fully retracted. A motorized nut (15) turns on the shaft
of the sectoring device to allow it to remain at a constant
distance from the blades as the segments deploy.
[0118] FIGS. 10A to 10C illustrate the inside framing of the
two-piece sectoring mechanism. The segment actuators (14) are fixed
to the vertical spokes of the sectoring device. As the actuators
extend the segments deploy, as the actuators retract the segments
retract. FIG. 10A illustrates fully or 100% deployed segments, FIG.
10B a 50% deployment of segments and FIG. 10C a 0.0% deployment of
segments. The segment guides (10) hold the segments in place, the
outer ring (11) fastens the base of the cone to the inside face of
the shroud, the actuator support rods (12) support the actuators,
the actuator rods (13) extend and retract from the actuator housing
(14).
[0119] FIG. 11 illustrates a two-zone sectoring apparatus equipped
with a motorized fan drive (14), compressor fan (15) two upstream
wind measurement devices (17), the vertical holding rod (16) that
keeps the measurement devices outside the effects of the compressor
fan, and the dead weight (18) that keeps the holding rod
stationary. It is the shaft that connects the vertical holding rod
to the turbine rotor shaft that is equipped with an internal roller
bearing that permits the holding rod to remain vertical.
[0120] Operational performance of the present invention is
described in the non-limitative following examples that were
derived from recognized computer simulation software applied by
recognized experts in the field of wind turbines.
[0121] To assess quantitatively the effects of using the swept area
sectoring system on augmented HAWT and VAWT (Vertical Axis Wind
Turbine, described in more detail below), two computer programs,
which have the capability to calculate the performance (power
output) of such wind turbines, have been used. For HAWT analysis
the code used was WT Perf, and for VAWT analysis, the CARDAAV code
has been used.
The WT Perf Code
[0122] WT Perf uses blade-element momentum (BEM) theory to predict
the performance of HAWT. It was developed at National Renewable
Energy Laboratory (NREL) from the code PROP, originally set up by
Oregon State University decades ago. The staff at the National Wind
Technology Center from the National Renewable Energy Laboratory,
USA, has recently modernized PROP by adding new functionalities
developed into the current WT Perf.
The CARDAAV Code
[0123] CARDAAV is a computer code developed by Ion Paraschivoiu for
the prediction of the aerodynamic qualities and the performances of
the vertical axis wind turbines.
[0124] CARDAAV is based on the Double-Multiple-Streamtube model
with variable upwind- and downwind-induced velocities in each
streamtube (DMSV). Due to this model and to a quite large number of
options regarding the geometrical configuration, the operational
conditions and the control of the simulation process, CARDAAV
proves to be an efficient software package, appropriate for the
needs of VAWT designers. It computes the aerodynamic forces and
power output for VAWTs of arbitrary geometry at given operational
conditions.
[0125] The numerous parameters that are necessary to fully describe
the analyzed VAWT provide a rather large freedom in specifying its
geometry. Among the most important in this category are: the rotor
height and diameter, the number of blades and the type of airfoil
defining their cross-section, the diameter of the central column
(tower), the size and position of the struts, the size of the
spoilers, etc. Virtually any blade shape can be analyzed,
including, of course, the straight one. Moreover, the blade can be
made of segments having different chord lengths and cross-sections
(airfoils). The airfoil data-base of the code includes some of the
well known symmetrical NACA shapes (NACA 0012, NACA 0015, NACA
0018, NACA 0021) as well as several of those specially designed for
VAWTs at Sandia National Laboratories (SNLA 0015, SNLA 0018, SNLA
0021). If the user wants to perform the analysis with an airfoil
that is not among those already available, this can be done quite
simply, by including the values of its experimentally determined
lift and drag coefficients in the actual airfoil data base. These
data must be given for several Reynolds numbers that correspond to
those attained on the revolving blades and cover (at each Re) the
full 360.degree. range for the angle of incidence
(0.degree..ltoreq..alpha..ltoreq.360.degree.).
[0126] Among the principal operating parameters that are readily
modifiable to meet the needs of a specific analysis one can
mention: the wind speed, the rotational speed of the rotor, the
local gravity acceleration and the working fluid properties
(density, viscosity--usually for air). Either constant rotational
speed at different wind speeds or different rotational speeds at a
constant wind speed can be considered when performing an analysis.
By specifying the adequate value for the atmospheric wind shear
exponent, a power law type variation of the wind speed with height
will be taken into account during the computations.
[0127] In what regards the control parameters, the code requires
the number of half cycle (azimuthal) divisions and vertical
divisions which define the total number of stream tubes that are
going to be considered in the computations as well as the number of
integration points over the width of each tube. In the same
category, the user has to specify the maximum number of iterations
in the computation of the upwind and downwind interference factors
along with the convergence criteria (relative error levels that
must be satisfied when computing the interference factors and the
dynamic stall). The decision on whether to apply or not the
aerodynamic corrections related to the blade-tip effects and those
due to the occurrence of the dynamic stall must be taken when the
control parameters are specified. Four dynamic stall models are
available, three derived from Gormont's method and the "indicial"
model.
[0128] The important number of parameters and options (mentioned
above) give CARDAAV a rather large capacity and flexibility in
computing the performances of various Darrieus type VAWTs.
Depending on the actual values given to these parameters, the code
performs the computations on a particular configuration by
neglecting or taking into account the effects of the dynamic stall
as well as several "secondary effects", such as those due to the
rotating central column, the struts and spoilers. The dynamic stall
has a significant influence on the aerodynamic loads and the rotor
performances at low tip-speed ratios, whereas the "secondary
effects" are important at moderate and high tip-speed ratios.
[0129] Running under the Microsoft Windows environment, CARDAAV is
user-friendly, being provided with a graphical interface so that
all the input data that need to be frequently changed for a
comprehensive performance analysis (rotor geometry, operational and
control parameters) is easily modified. The local induced
velocities, Reynolds number and angle of attack, the blade loads
and the azimuthal torque and power coefficients are the output
data. These results can be directly visualized on the computer's
display or stored in ASCII files or in a format compatible with the
graphic software TECPLOT (Amtec Engineering Inc.) for further post
processing and interpretation.
[0130] Numerous validations have demonstrated the capacity of
CARDAAV to compute with a fair accuracy the aerodynamic loads and
global performances (torque, power) of the usual types of vertical
axis wind turbines, including those of Darrieus H-type. The CARDAAV
results compare quite well with the experimental ones over a large
range of tip speed ratios (TSR).
[0131] The simulation was performed using as the reference a
standard 22-meter diameter HAWT blade. The simulations were carried
out on shrouded rotors at wind speeds of 4, 7 and 12 m/s. The
sectoring ratio was varied between 1.0 and 0.25. The effect and
advantages of sectoring the rotor are clearly illustrated by the
test results as shown in FIG. 12.
[0132] The form of the sectoring device for the simulation was a
cone shape. The effect of changing the form of the sectoring device
was not evaluated, only the effect of the change in swept area.
Many different forms of sectoring device are applicable including
parabolas, cones and semi-circles and the form may improve slightly
the result. However the important variable remains the change in
the sectored area that has the effect of increasing the wind
pressure at the face of the blades and the application of this wind
pressure to the optimum high torque zone of the rotor.
[0133] The simulated results of sectoring were achieved using a
standard 22-meter HAWT blade. The cord and twist angle distribution
are depicted in FIG. 13.
[0134] The results of the simulations are listed in Table 1 and
depicted as continuous curves in FIG. 12.
TABLE-US-00001 TABLE 1 Power generated versus sectoring ratio 22
meter HAWT rotor at wind speeds of 4.0, 7.0, and 12 m/s 4.0 m/s 7.0
m/s 12.0 m/s SR Power generated (kW) 1.0 10 30 190 0.9 20 30 210
0.8 20 40 225 0.7 30 50 260 0.6 30 70 300 0.5 40 100 550 0.4 40 150
750 0.3 50 220 1150 0.25 55 300 1500
Example 1
A HAWT Sectored Rotor at 4.0 m/s
[0135] At 4.0 m/s the sectoring ratio was varied between 1.0 and
0.25. The power produced increased from 10 to 55 kW or an increase
of 5.5 fold.
Example 2
A HAWT Sectored Rotor at 7.0 m/s
[0136] At 7.0 m/s the sectoring ratio was varied between 1.0 and
0.25. The power produced increased from 30 to 300 kW or an increase
of 10 fold.
Example 3
A HAWT Sectored Rotor at 12.0 m/s
[0137] At 12.0 m/s the sectoring ratio was varied between 1.0 and
0.25. The power produced increased from 190 to 1500 kW or an
increase of 7.7 fold.
[0138] As a person skilled in the art would understand a plurality
of types of axial flow or horizontal axis turbines may be used with
the device of the present invention. Also for each wind turbine
different combinations may be used for example a different number
and/or configuration of blades, the space between the wind section
and the wind turbine, etc.
[0139] As a person skilled in the art would understand the
parameters of the sectoring cone may differ from the examples shown
in this document. Similarly the mechanism for adjusting the opening
of the aperture or flow channel may differ based on the fluids,
operating conditions and turbine apparatus.
Embodiments for Cross-Flow Turbines
[0140] According to the present invention, as shown in FIG. 18,
there is also provided a directing system 1800 for directing fluid
entering a cross-flow turbine along an inlet flow direction. The
turbine comprises a rotor. The rotor comprises a plurality of
turbine blades 1802. The directing system 1800 comprises an inlet
1808 directing fluid towards the turbine, and a plurality of
directing segments 1804 attached to the inlet 1808, downstream of
the inlet. A directing segment adjustment system 1806 is also
provided for adjustably positioning the directing segments 1804
between a retracted configuration and a deployed configuration. The
directing segments, in the deployed configuration, extend beyond
the inlet 1808 in a direction transversal to the inlet flow
direction and deflect the fluid towards a centerline 1801 of a
rotor of the turbine.
[0141] Preferably, the plurality of directing segments 1804 are two
inlet side deflectors pivotably attached to the inlet and the
directing segment adjustment system 1806 comprises a pair of
actuators for pivoting the two side deflectors with respect to the
inlet.
[0142] Preferably, the directing system further comprises an outlet
1809 directing fluid away from the turbine, a second set of two
outlet side deflectors 1805 pivotably attached to the outlet and a
second pair of actuators for pivoting the second set of the two
outlet side deflectors with respect to the outlet.
[0143] Preferably, the directing system further comprises a set of
adjustably positionable side baffle plates 1803 concentrically
positioned within an outer circumference of the rotor of the
turbine.
[0144] Preferably, the directing system further comprises a set of
baffle plate actuators for adjustably positioning the side baffle
plates 1803 based on a corresponding configuration of the inlet
side deflectors or directing segments 1804.
[0145] Preferably, the set of adjustable baffle plates are
supported by a set of support bars 1807 attached to a shroud
surrounding the turbine.
[0146] Preferably, the directing segment adjustment system
comprises a controller and the directing system further comprises a
fluid velocity measurement system located upstream of the inlet and
producing a signal indicative of fluid velocity entering the
turbine, and wherein the controller adjusts the directing segment
adjustment system based on the signal indicative of fluid velocity
entering the turbine.
[0147] According to the present invention, there is also provided a
rotor-sectoring device for use with at least one wind turbine to
increase the velocity pressure and maximize the torque produced by
the wind contacting the blades of the wind rotor, the
rotor-sectoring device comprising: [0148] (a) a shrouded tunnel
section, the tunnel section comprising four walls an entry and an
exit, the entry having an area equal or slightly lower than the
exit; [0149] (b) an entrance and exit adapters, the adapters
designed to minimize the loss of velocity pressure as the air
stream enters and leaves the wind turbine; [0150] (c) a set of two
pivoting side deflectors located both upstream and downstream of
the wind rotor; [0151] (d) a set of actuators that deploy or
retract the upstream side deflectors into the air stream, the width
or cross section of the air stream being controlled by the
actuators or the side wall deflectors; [0152] (e) a set of
actuators that deploy or retract the downstream side deflectors
into the air stream, the width or cross section of the air stream
being controlled by the actuators or the side wall deflectors;
[0153] (f) a set of adjustable position side baffle plates located
within the circumference defined by said turbine rotor and
traveling back and forth in synchronous fashion with the adjustable
side deflectors and thereby controlling the size of the flow
channel; [0154] (g) a set of actuators to position the side wall
baffles in synchronous fashion with the side wall deflectors;
[0155] (h) a wind measurement instrument located upstream of the
entrance adapter and providing a continuous measurement of wind
speed to a programmable controller; [0156] (i) the programmable
controller adjusting the position of the deflectors and the side
baffles to control the sectoring ratio and the speed through the
adjustable flow aperture.
[0157] Preferably, the rotor-sectoring device produces a square or
rectangular shaped channel at the face of the rotor blades of
variable dimensions by increasing or decreasing the width of said
sectoring device.
[0158] Preferably, the rotor-sectoring apparatus is capable of
adjusting the area of the flow aperture of the turbine rotor.
[0159] Preferably, the sectoring cone is of such dimensions that it
can be mounted on the shrouds of the turbine rotor in order to
rotate with the turbine into the wind.
[0160] Preferably, the rotor-sectioning device has an aerodynamic
form that maximizes the wind pressure at the face of the rotor
blades.
[0161] Preferably, the rotor-sectioning cone optimizes the
production of power by limiting the flow aperture to dimensions
that maximize the torque produced by decreasing the low torque
zone.
[0162] Preferably, the rotor-sectioning device directs the air
stream to the optimum section of the rotor blades to develop the
maximum torque per unit of air volume at all wind speeds.
[0163] Preferably, the rotor-sectioning cone can increase the power
generated significantly by a conventional VAWT or cross-flow
turbine at evaluated wind speeds of 4.0, 7.0 and 12.0 m/s.
[0164] Preferably, the rotor-sectioning apparatus can increase the
power output of existing VAWT wind turbines by retrofitting the
apparatus to the existing VAWT rotor or turbine.
[0165] Preferably, the rotor-sectioning apparatus performs
satisfactorily with non-augmented or augmented axial flow wind
turbines.
[0166] Preferably, the rotor-sectioning apparatus, by dynamic
similitude, will provide very similar overall performance when
either water or air are the fluids passing through the turbine.
[0167] The blades of a cross-flow turbine such as a VAWT do not
provide a continuous level of torque over each revolution. Whether
the rotor is shrouded or operating in an open channel the torque
developed varies as the blades travel around their 360-degree path.
Similar to the HAWT, as shown in FIG. 14, there exists a low torque
area 1420 and a high torque area 1410. When looking at a vertical
cross-flow rotor along the direction of its shaft, the high torque
sector of the upwind and downwind arcs is centered on the 12
o'clock and 6 o'clock positions. The low torque sectors are
centered on the 3 o'clock and 9 o'clock positions. Thereby, in the
case of a VAWT rotor, the zones of "low torque" (hence low power
production) are situated on the two sides of the rotor swept area,
whereas the "high torque" zone coincides with the central part of
the rotor swept area as shown by FIG. 14.
[0168] The azimuthal variation of the tangential force FT of a
generic VAWT is illustrated in FIG. 15.
[0169] The purpose of installing a sectoring apparatus on a VAWT is
to direct air away from the low torque area and into the high
torque area. Computer simulations have permitted to determine that
the power produced will continue to increase until the area
sectored represents 67% of the total swept area. Above 67% the
power output falls rapidly.
[0170] The sectoring device creates an adjustable rectangular or
square opening at the upwind and downwind faces of the rotor. The
side deflectors are adjustable to decrease the width of the
aperture. Essentially this removes airflow from the walls or the
low torque areas and directs it to the high torque area located
along the rotor centerline. The reduction in the area of the
aperture increases the wind velocity pressure.
[0171] The rotor is shrouded in order to prevent the air from
spilling around the edge of the blades. A bell shaped lip on the
upwind entrance and an angled or round lip on the downwind exit
serve to minimize the entrance and exit friction losses.
[0172] It is important that the side deflectors attached to the
turbine shrouds have a suitable aerodynamic shape for each
application and fluid. For an application where choking of the
fluid stream becomes a problem a baffle plate is installed in line
with the turbine shaft to cut the non-sectored area into two equal
parts. The walls of this baffle have a slight outward radius.
[0173] In order to reduce velocity pressure losses when the air is
traveling between the rotors two adjustable baffles are installed
inside the rotor parallel to the direction of wind flow. As the
side deflectors move to increase or decrease the width of the
aperture their horizontal displacement and the horizontal
displacement of the baffles are synchronized. The effect is to
create a more continuous flow channel up to and through the rotor
blades.
[0174] The sectoring of VAWT is applicable for augmented and
non-augmented turbines. In all cases the rotor is shrouded or
ducted. FIGS. 16 and 17 show the construction principle for
non-augmented (including a turbine shroud 160, shroud inlet 162 and
shroud outlet 164) and for augmented turbines (including a turbine
170, convergent inlet 172, diffuser 174, side plates 176,
adjustable upwind vanes 178, adjustable downwind vanes 180)
respectively.
[0175] FIG. 18 shows the principal sections of the rotor-sectoring
apparatus for cross-flow turbines which are the rotor shaft (1801),
the rotor airfoils (1802), the adjustable baffle walls (1803), the
upwind flow deflectors (1804), the downwind flow deflectors (1805),
the upwind and downwind flow deflector actuators (1806), the
adjustable baffle wall actuators (1807), the entrance flow adapter
(1808), the exit flow adapter (1809) and the shrouds covering the
top bottom and sides of the turbine section. The top shroud is not
shown for purposes of clarity and comprehension.
[0176] Operational performance of the present invention is
described in the non-limitative examples that are computer
simulations prepared using recognized computer simulation programs
by competent recognized experts in the fields of simulating wind
turbines. The tools, method and techniques are discussed in the
previous section of this document.
[0177] The examples described below have been executed with a
vertical airfoil with characteristics as shown in Table 2. The
rotor has been equipped with shrouds and the effect of the
rotor-sectoring device was evaluated at wind speeds of 4.0, 7.0 and
12.0 m/s.
TABLE-US-00002 TABLE 2 Power versus SR at 4.0, 7.0 and 12.0 m/s 4.0
m/s 7.0 m/s 12.0 m/s SR Power generated in kW 1.0 10 50 200 0.9 15
60 290 0.8 25 75 380 0.7 30 110 560 0.67 35 120 625
Example 1
A VAWT and Sectored Rotor at 4.0 m/s
[0178] At 4.0 m/s the sectoring ratio was varied between 1.0 and
0.67. The power produced increased from 10 to 35 kW or an increase
of 3.5 fold.
Example 2
A VAWT and Sectored Rotor at 7.0 m/s
[0179] At 7.0 m/s the sectoring ratio was varied between 1.0 and
0.67. The power produced increased from 50 to 120 kW or an increase
of 2.5 fold.
Example 3
A VAWT and Sectored Rotor at 12.0 m/s
[0180] At 12.0 m/s the sectoring ratio was varied between 1.0 and
0.67. The power produced increased from 200 to 625 kW or an
increase of 3.1 fold.
[0181] The results obtained are shown as curves in FIG. 19.
[0182] As a person skilled in the art would understand a plurality
of types of cross-flow or vertical axis turbines may be used with
the device of the present invention. Also for each wind turbine
different combinations may be used for example a different number
and/or configuration of blades, the space between the wind section
and the wind turbine, etc.
[0183] As a person skilled in the art would understand the
parameters of the sectoring cone may differ from the examples shown
in this document. Similarly the mechanism for adjusting the opening
of the aperture or flow channel may differ based on the fluids,
operating conditions and turbine apparatus.
[0184] While illustrative and presently preferred embodiments of
the invention have been described in detail hereinabove, it is to
be understood that the inventive concepts may be otherwise
variously embodied and employed and that the appended claims are
intended to be construed to include such variations except insofar
as limited by the prior art.
* * * * *