U.S. patent application number 09/923649 was filed with the patent office on 2002-09-05 for low drag ducted ram air turbine generator and cooling system.
Invention is credited to Ghetzler, Richard, Kruse, Neils, Schmulenson, Harold, Stephens, Kendal R., Wojtalik, Jerome F. JR..
Application Number | 20020122717 09/923649 |
Document ID | / |
Family ID | 22342314 |
Filed Date | 2002-09-05 |
United States Patent
Application |
20020122717 |
Kind Code |
A1 |
Ghetzler, Richard ; et
al. |
September 5, 2002 |
Low drag ducted ram air turbine generator and cooling system
Abstract
A low drag ducted ram air turbine generator and cooling system
is provided. The ducted ram air turbine generator and cooling
system has reduced drag with respect to prior ram air turbine
generator systems while extracting dynamic energy from the air
stream during the complete range of intended flight operating
regimes. A centerbody/valve tube having an aerodynamically shaped
nose is slidably received in a fairing and primary structure to
provide a variable inlet area. An internal nozzle control mechanism
attached to the valve tube positions nozzle control doors to
provide variable area nozzles directing air flow to the turbine
stator and rotor blades to maintain optimum generator efficiency.
An alternate embodiment includes an annular internal nozzle having
interleaved panels to modulate the air flow to the turbine.
Inventors: |
Ghetzler, Richard; (Buffalo
Grove, IL) ; Wojtalik, Jerome F. JR.; (Hoffman
Estates, IL) ; Kruse, Neils; (Cary, IL) ;
Stephens, Kendal R.; (Fox River Grove, IL) ;
Schmulenson, Harold; (Buffalo Grove, IL) |
Correspondence
Address: |
Edward J. Chalfie
Suite 5125
311 South Wacker Drive
Chicago
IL
60606-6622
US
|
Family ID: |
22342314 |
Appl. No.: |
09/923649 |
Filed: |
August 6, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09923649 |
Aug 6, 2001 |
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09461551 |
Dec 14, 1999 |
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6270309 |
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60112141 |
Dec 14, 1998 |
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Current U.S.
Class: |
415/35 |
Current CPC
Class: |
F02C 7/042 20130101;
F01D 15/10 20130101; F01D 17/06 20130101; Y10T 137/0645 20150401;
Y02T 50/60 20130101; Y10T 137/0536 20150401; F01D 17/14 20130101;
F01D 25/12 20130101; F05D 2220/34 20130101; B64D 41/007
20130101 |
Class at
Publication: |
415/35 |
International
Class: |
F01D 017/06 |
Claims
What is claimed is:
1. Ram air turbine apparatus comprising: a generally cylindrical
external fairing having a leading end and an aft end, with an air
inlet passage at said leading end, and with a plurality of external
exhaust ports proximate said aft end; a support structure radially
proximate the inner surface of said external fairing, said fairing
supported by said support structure, said support structure
including a plurality of axial spars, a central flow guide
coaxially located within and supported by said support structure,
said guide having an outer surface spaced from said support
structure, a valve tube coaxially located intermediate said support
structure and said central flow guide in radial proximity to said
primary support structure, said valve tube being axially movable
with respect to said external fairing and having an aerodynamically
contoured nose end, a plurality of openings aft said nose end of
said valve tube enabling flow of air from said air inlet passage
through an annular passage formed between an inner surface of the
valve tube and said outer surface of said center flow guide, a
turbine wheel having vanes, a stator means having vanes for
directing air flow to said turbine vanes, at least one nozzle in
said annular passage between the outer surface of said central flow
guide and said inner surface of said movable valve tube secured to
said center flow guide and extending outward in close proximity to
the inner surface of said movable valve tube, said at least one
nozzle axially extending from a position proximate to said aft end
of said air inlet in said external fairing to a position in close
proximity to said stator vanes, said valve tube being movable
between a first position wherein said contoured nose of said valve
tube end is in line with the leading edge of said fairing front end
such that a maximum flow area is presented to the air stream in
said air inlet allowing maximum air flow through the air inlet,
said at least one nozzle, said stator vanes, said turbine vanes,
and through said fairing external exhaust ports to a surrounding
region, and a second position wherein said valve tube is advanced
forward so that the contoured nose end of said valve tube restricts
said air inlet area so that reduced airflow occurs through said air
inlet, said at least one nozzle, said stator vanes, said turbine
vanes, and said fairing external exhaust ports to the surrounding
region, and a third position wherein said valve tube is advanced to
a maximum forward position so that the contoured nose of the valve
tube contacts the inner surface of the fairing air inlet in a
manner such that said air inlet is completely closed.
2. The ram air turbine apparatus of claim 1, further comprising a
nozzle control intermediate said valve tube and said central flow
guide operable to control flow of air through said nozzles in
response to movement of said valve tube between said first, second
and third positions.
3. The ram air turbine apparatus of claim 2, wherein said nozzle
control includes: a plurality of circumferentially spaced control
doors positioned between and pivotally supported between a pair of
parallel nozzle side walls for movement between retracted positions
substantially contiguous with the inner surface of said valve tube
and extended positions projecting radially inward into said nozzle,
a cam follower mounted on each of said control doors at a position
spaced from said respective pivotal support of said respective
door, and a slot in each said nozzle side wall forming a cam,
whereby movement of said respective cam follower in said respective
slot moves said respective control door between a fully retracted
position and a fully extended position.
4. The ram air turbine apparatus of claim 3, wherein said nozzle
control maintains a fixed ratio of the total exhaust areas of the
nozzles to the area of the air inlet passage.
5. The ram air turbine apparatus of claim 2, wherein said nozzle
control includes: a plurality of alternately interleaved primary
and secondary nozzle control panels positioned between and
pivotally supported on a panel mounting ring for movement between
retracted positions substantially contiguous with the inner surface
of said valve tube and extended positions projecting radially
inward into said nozzle, a cam slot mounted on each of said primary
nozzle control panels at a position spaced from said respective
pivotal support of said primary nozzle control panels on said panel
mounting ring, and cam followers mounted on said valve tube,
whereby movement of said respective cam followers in said
respective cam slots urges said primary nozzle control panels and
said interleaved secondary nozzle control panels between a fully
retracted position and a fully extended position.
6. The ram air turbine apparatus of claim 5, wherein said nozzle
control maintains a fixed ratio of the total exhaust areas of the
nozzles to the area of the air inlet passage.
7. Ram air turbine generating apparatus comprising: a generally
cylindrical external fairing having a leading end, said fairing
tapered radially inward toward said leading end with a primary air
inlet passage at said leading end, and the external fairing
extending to an aft end, and having a plurality of external exhaust
ports proximate said aft end, a primary structure means radially
proximate the inner surface of said external fairing, extending the
length of said fairing means, said fairing means mounted to said
primary structure, said primary structure including a plurality of
straight axial spars extending the length of said external fairing,
central flow guide means mounted to said support structure and
coaxial therewith, said guide means having an outer surface spaced
from said structure means, centerbody/valve tube means intermediate
said primary structure means and said central flow guide means
coaxial therewith and in radial proximity to said primary structure
means, said centerbody/valve tube means including an
aerodynamically contoured nose end with an aft tubular body with
the tube connected to the aft larger valve tube portion of the
centerbody/valve tube assembly with aerodynamic shaped spars
spanning the increased diameter, a plurality of openings therewith
set back at a distance from the nose end of said centerbody/valve
tube aft end enabling flow of air into and through the openings in
said nose end and through an annular passage formed between the
inner surface of the valve tube and said center flow guide, a
turbine wheel having blades and drivingly coupled to a generator or
hydraulic pump or both, stator means for directing air flow to the
turbine blades, a plurality of nozzle means, each formed in radial
extent in the annular passage between the outer wall of said
central flow guide and inner wall of said movable valve tube and in
circumferential extent between a set of parallel nozzle side wall
means, said nozzle sidewall means consisting of plates mounted to
the center flow guide and extending outward within close proximity
to the inner wall of said movable valve tube means, and said nozzle
side wall means; and said nozzle means extending in axial extent
from an axial position proximate to the aft end of said primary air
inlet in said external fairing and extending afterward to a
position in close proximity to said stator, said valve tube means
being movable between a first position whereat said contoured nose
of said valve tube end is in line with the leading edge of said
fairing front end such that a maximum area flow area is presented
to the air stream in said primary inlet of said external fairing
allowing maximum air flow through said primary air inlet, through
said plurality of inlet holes in said contoured nose of said valve
tube, through said annular nozzle means, through said stator,
through said turbine, through an exhaust deflector and said fairing
exhaust ports to the surrounding region; and a second position
whereat said valve tube is advanced forward so that the contoured
nose end of said valve tube restricts the area of said primary air
inlet so that reduced airflow occurs through said primary air
inlet, through said plurality of inlet holes in the contoured nose
of said valve tube, through said annular nozzle means, through said
stator, through said turbine, through said exhaust deflector and
said fairing exhaust ports to the surrounding region; and a third
position whereat said valve tube is advanced forward to a maximum
forward position so that the contoured nose of the valve tube
contacts the inner surface of the fairing primary air inlet in the
manner such that the inlet is completely closed, speed sensor means
for detecting the speed of said turbine wheel; and an actuator and
speed control means responsive to said speed sensor means for
moving said valve tube forward toward the second position when the
speed of said turbine wheel exceeds a predetermined value, thereby
reducing the primary inlet flow area and air flow through the
primary air inlet, nozzle means, and to the turbine; thereby
returning the speed of said turbine wheel to the predetermined
speed, said actuator and speed control means responsive to said
speed sensor means for moving said valve tube afterward toward the
first position when the speed of said turbine wheel is less than a
predetermined value, thereby increasing the inlet flow area and air
flow through the primary air inlet, nozzle means, to the turbine;
returning the speed of said turbine wheel to the predetermined
speed, said actuator and speed control means responsive to external
control for moving said valve tube forward toward the third
position when power output is to stopped thereby completely closing
the inlet flow area.
8. The ram air turbine generating apparatus as set forth in claim 7
including: nozzle control means intermediate said valve tube means
and said central flow guide means operable to control flow of air
through the nozzle in response to movement of said valve tube means
between the first, second, and third positions.
9. The ram air turbine generating apparatus as set forth in claim 8
wherein said nozzle control means includes: a plurality of
circumferentially spaced control doors positioned between and
pivotally mounted to each of said nozzle side vanes for movement
between retracted positions substantially contiguous with the inner
surface of said valve tube means and extended positions projecting
radially inward into the annular nozzle, a plurality of cam
followers, each said cam follower being rotatably mounted to shafts
attached to and extending circumferentially outward from each of
said control doors adjacent to the end of the respective door and
opposite said respective door mounting pivot, a slot in each said
side wall of said nozzle side vanes whereby the motion of said
respective shaft of said cam followers is accommodated in said
nozzle side vanes when said respective nozzle control door moves
between a fully retracted position and an extended position, a
plurality of twin cams, each said twin cam mounted axially to the
inner surface of said valve tube and extending radially inward into
the plurality of channels situated between the outboard surfaces of
adjoining one of said respective nozzle vanes, and a plurality of
torsion springs, each attached on one end to the outboard side of
said nozzle vanes in proximity to and engaged on the other end to
the cam follower shaft whereby outward forces are applied to said
cam followers maintaining contact between each cam follower and cam
for all positions of the cam and cam follower; whereby each side of
said twin cam simultaneously engages the adjacent cam followers
from either side of adjacent said control doors, whereby each of
said control doors is held in the retracted position when said
valve tube is in the first position, and whereby each of said
control doors is held in the extended position when said valve tube
means is in the second position.
10. The ram air turbine generating apparatus as set forth in clam 8
including track means for radial positioning and allowing axial
sliding motion of said valve tube relative to said primary
structure, wherein said track means consists of a plurality of
grooves in the radial inboard surface of said longitudinal spars of
said primary structure, each said groove accommodating a matching
protruding member of said valve tube which slides in said groove
with low friction.
11. The ram air turbine generating apparatus as set forth in claim
8 wherein said central flow guide means has an axial bore therein;
and wherein said valve tube means aft end is slidably received in
the axial bore of said central flow guide means.
12. The ram air turbine generating apparatus as set forth in claim
7 wherein said valve tube means includes an aerodynamic shaped
forebody forming said contoured nose end, a plurality of air inlet
channels are spaced circumferentially around and set back from the
nose end of said contoured nose, a cylindrical body connected to
said contoured nose end with aerodynamically shaped spars, and
extending afterward to an axial position in close proximity to the
front of said stator, and a plurality of said aerodynamically
shaped spars connecting the smaller diameter contoured nose to the
aft larger diameter valve tube.
13. The ram air turbine generating apparatus as set forth in claim
12 including a turbine with a turbine shaft rotatably mounted at
the forward end to the aft side of an aft plate member of said
center flow guide and on the aft end to a plate mounted to the
primary structure.
14. The ram air turbine generating apparatus as set forth in claim
13 including a forward bearing on said central flow guide means for
rotatably mounting said one end of said turbine shaft and an aft
bearing on said turbine aft plate of the primary structure bulkhead
for rotatably mounting said other end of said turbine shaft.
15. The ram air turbine generating apparatus as set forth in claim
14 including a generator mounted to the aft side of an axially
positioned generator mounting plate which is mounted to the primary
structure, wherein said generator mounting plate has a bearing for
rotatably mounting the shaft of said generator, with a portion of
said generator shaft extending forward through said bearing; and a
shaft coupler for drivingly coupling said aft shaft of said turbine
to said generator shaft.
16. The ram air turbine generating apparatus as set forth in claim
7 wherein said actuator and speed control means includes an
electronic speed control circuit and an actuator controlled by said
speed control circuit for positioning said valve tube afterward
toward the first position when increased speed is needed to match
the required turbine speed, and forward toward the third position
when decreased turbine speed is needed to match the required
turbine speed.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to ram air turbine
devices and more particularly to a ducted type ram air turbine
generator.
[0003] 2. Description of the Prior Art
[0004] One type of ram air turbine generator disclosed in the prior
art consists of a ram turbine generator with the blades mounted
externally to extract power from an air stream. The blades are
usually mounted to a rotatable housing forming part of a center
aerobody with the turbine center shaft drivingly coupled to an
electric generator, or a hydraulic pump, or both if desired.
Turbine speed control and power output are maintained through speed
control mechanisms which vary the pitch of the blades under varying
flight conditions, thereby tending to maintain constant power to
the blades from the air stream. This type of ram air turbine
generator is presently the predominate type used on externally
carried electronic pods, primarily in military applications, and
for emergency power electric/and or hydraulic power. The units are
stored in the wing or fuselage of an aircraft and are deployed into
the air stream when there is failure of the onboard aircraft power.
Recent patents relate to improvements in this basic technology.
U.S. Pat. No. 5,249,924 (Brum) relates to mechanisms and controls
to adjust the pitch of the blades for speed control. U.S. Pat. No.
4,991,796 (Peters, et al) discloses a drive system between a ram
air turbine and power generator units aboard a host aircraft. U.S.
Pat. No. 5,122,036 (Dickes et al) discloses an externally bladed
ram air turbine generator with a mechanism to prevent blade stall
and to allow power generation at low speeds, including aircraft
landing approach and final landing.
[0005] The process of converting air stream power to mechanical
rotary power in externally bladed turbines, in terms of power
extracted relative to the power dissipated through drag, is
relatively efficient at low to moderate subsonic speeds. However as
the flight speed of the aircraft increases, to values where the
relative velocity between the air and blade becomes sonic,
efficiencies of the process fall off dramatically. In these regimes
the shock waves, induced by the blades, create high frontal
pressures on the blades and flow separation over and behind the
blades, with corresponding dramatic increases in drag. This can
occur at flight speeds in the range of Mach=0.60 depending on the
blade design and shaft rotational speed. As flight speed further
increases to high subsonic, through transonic, and into supersonic
flight regimes, the drag to lift ratio can further increase at
least several times depending on blade profile, reflecting equal
increases in the drag for the same power extracted from the air
stream, which is produced by the blade lift. These drag increases
can be critical in applications to electronic pods mounted to high
performance supersonic fighter aircraft. With increasing power
needs for electronic systems in external aircraft pods, this drag
penalty for the external turbine bladed technology has increasing
undesirable impact on aircraft performance, adversely affecting
speed, maneuverability and range. In addition, external bladed ram
turbine generators do not have the capability to provide direct
cooling from the exhaust air. In applications where portions of the
flight profile include high speed flight which induces significant
aerodynamic heating on the skin of a pod, additional active cooling
systems are required for the pod electronics, entailing additional
size and weight penalties.
[0006] Ducted ram air turbine generators are a second type of ram
air turbines. U.S. Pat. No. 4,267,775 (Sjotun) discloses a ram air
turbine generator positioned internally, in the nose of a missile,
with a wreath arrangement of inlet ducts supplying ram air to the
inlet of a radial flow turbine. Outlet ducts direct the exhaust
flow forward. During supersonic flight of the missile, the shock
waves off the front of the missile increase the pressure in front
of the exhausts, tending to increasingly throttle the flow through
the ducts and turbine as the missile accelerates, thereby tending
to limit the maximum speed of rotation of the turbine. However,
drag reduction features were not a goal and were not present. The
drag is large for the power extracted, due to the reaction forces
set up from the full reversal of the air inlet stream, and the
resistance to the exhaust flow from the oncoming air stream. No
direct cooling capability is provided.
[0007] U.S. Pat. No. 4,477,039 (Boulton, et al) discloses a vented
cowl variable geometry inlet for aircraft. A variable area vent, in
the side of an air inlet cowl with a slidable door, can be
positioned to allow air flow dumping, thereby permitting starting
with high contraction inlets, for example as used in ram jets, and
to control airflow to the engine during flight. The system is
intended for use with supersonic aircraft air induction systems
associated with air driven auxiliary power equipment. The system
controls airflow supply to air driven power equipment, as is needed
for speed and power control. However, the basic approach offered,
including the air induction and then venting, with the shape of the
leading edge of the door diverting the flow outward through vents,
inherently does not offer a reduced drag.
[0008] Present inventor Ghetzler's earlier invention entitled "Ram
Air Turbine Generating Apparatus", U.S. Pat. No. 5,505,587
discloses a ducted ram air turbine that obtains some measure of
power output and speed control from purely aerodynamic and spring
activated mechanical internal control elements. However, the ducted
ram air turbine of that invention results in speed and power
variation as great as thirty percent above or below a nominal
design value throughout moderate subsonic through supersonic flight
speed range. For many airborne applications the final power
supplied to electronic systems requires a tighter tolerance on
power and speed usually in the range of five percent. Thus, the use
of this earlier invention may entail additional power conditioning
systems with increasing size and weight penalties. This earlier
invention has bypass features which admit and then bypass and
exhaust a portion of the airflow before entering the turbine. As in
the Boulton, et al, patent, the process of admitting, bypassing,
and then exhausting airflow presents drag penalties due to the
momentum interchange.
[0009] It is with the knowledge of the state of the present
technology and limitations of that technology as just set forth,
that the present invention was conceived and now has been reduced
to practice.
SUMMARY OF THE INVENTION
[0010] The ram air turbine of this invention is designed to reduce
drag in the process of extracting dynamic energy from the air
stream and converting the energy to hydraulic and/or electric power
during the complete range of intended flight operations. The
intended operating flight regime for this invention is moderate to
high subsonic through supersonic. Under conditions when power
generation is not required, an aerodynamic shaped centerbody is
advanced forward in the inlet completely shutting off the air inlet
flow while presenting a low drag forebody to the air stream,
thereby also minimizing drag induced by the presence of the device
during the non operating mode. In addition to power generation
capability, the present invention has the capability of providing
cooling air flow to the generator and other external electronic
equipment if desired, through the use of the exhaust air from the
turbine which has been cooled in the process of performing work on
the turbine.
[0011] In accordance with this invention, a ram air turbine
generator comprises a generally cylindrical external fairing having
an air inlet at the leading end and external exhaust ports
proximate the aft end. The external fairing is mounted to a primary
structure consisting of longitudinal spars which in turn are
attached to several axially positioned rings in the forward part
and structural bulkheads in the rear part of the fairing. An
axially movable centerbody/cylindrical valve tube structure is
coaxial with, and positioned inside the fairing and primary
structure forward of the bulkhead structure, and radially proximate
the inner surfaces of the axial spars and rings. An aerodynamically
shaped forward nose acts as a centerbody in the air inlet. The
forward nose is of smaller maximum diameter than the aft
cylindrical valve tube. The aft part of the forward nose is
attached to the aft cylindrical valve tube by aerodynamic shaped
vanes which span the increased radius.
[0012] The centerbody/valve tube is slidable relative to the
fairing and primary structure on axial slide mechanisms on the
inner surface of the longitudinal spars of the primary structure. A
coaxially mounted cylindrical center flow guide has an outer
surface spaced radially inward from the fairing and primary
structure with a front part slidably receiving the aft surface of
the centerbody of the centerbody/valve tube. The centerbody/valve
tube forward nose forms a centerbody of an annular variable area
air inlet. Air flows through an annular space between the outer
surface of the forward nose and the inner surface of the fairing,
into the annular openings in annular channels formed between the
aerodynamically shaped vanes, and then into an annular variable
area nozzle formed between the inner surface of a plurality of
nozzle control doors and the outer surface of the center flow
guide.
[0013] The centerbody/valve tube assembly is moveable between a
first maximum aft position (position 1), where the centerbody nose
end is axially in line with the front of the inlet, thereby
presenting the maximum inlet area to the air stream. A nozzle
control mechanism attached to the valve tube positions the nozzle
control doors to the maximum open condition. In this position,
maximum airflow is permitted in the variable area inlet and nozzle
passages, and through a stator and a turbine wheel, where a portion
of the air stream's dynamic energy is extracted, and out through an
exhaust deflector and the fairing external exhaust ports to the
external environment. The turbine is drivingly coupled to and
powers an electric generator.
[0014] In a second forward position (position 2), when maximum
generator power output is required, the nose is advanced forward of
the inlet plane, such that a minimum air inlet area is presented in
the annular region between the centerbody and inner fairing
surface. The nozzle control mechanism closes the nozzle control
doors to their maximum extent.
[0015] In response to a signal from a turbine speed sensor, an
electronic controller activates an electro-mechanical or
electro-hydraulic actuator to move the centerbody/forward valve
tube. The centerbody/forward valve tube is moved toward the second
forward position when flight conditions and generator load cause
the turbine to overspeed above a certain tolerance. The
centerbody/forward valve tube is moved toward the first position
when flight conditions and generator load cause the turbine speed
to fall below a predetermined speed, within a certain tolerance,
thereby tending to maintain the turbine wheel and generator speed
within a predetermined speed range.
[0016] Thus, in a full power extraction mode, under changing flight
conditions with varying air density and flight velocity, only
sufficient air flow with sufficient kinetic energy will be admitted
into the variable area diffuser and through the variable area
nozzle to the turbine to maintain close to constant fluid dynamic
power in the airflow through the turbine. Thereby the turbine and
generator speeds are maintained at their design values. The
variable area nozzles working in conjunction with the variable area
inlet, control the variation in the airflow velocity to the stator
and turbine to cause the turbine to efficiently extract energy from
the air stream throughout the moderate subsonic through supersonic
flight speed regime. The combination of admitting only the airflow
required, and of efficiently extracting energy throughout the
intended range of flight operation, minimizes drag throughout the
operating flight speed range. During portions of a flight, when
power requirements are reduced below normal operating levels, or
completely cease, the centerbody/valve tube is advanced partially
or completely forward toward a third or closed position, further
reducing or completely closing off the inlet air flow, and further
closing the nozzles, thereby presenting a clean aerodynamic
forebody, which further reduces drag in the reduced or ceased power
operating modes.
[0017] When cooling capability is desired or required for the
generator and/or additional electronic systems, cooling capability
is provided in an alternate embodiment of the present invention.
The shaft work, performed by the air flow through the turbine,
which is converted to electrical power by the generator, results in
the exhaust air having lower internal energy or temperature than
the total recovered temperature at the inlet. This cooled exhaust
air is exhausted directly to the external environment through the
exhaust duct when cooling effects are not needed. In the embodiment
of this invention providing cooling, a bypass valve is provided in
the exhaust duct for cooling control. When cooling is desired, the
bypass valve closes off flow to the outside and directs the cooled
turbine exhaust air downstream of the bypass valve through a
cooling duct into a heat exchanger. To minimize back pressure,
which would otherwise reduce turbine efficiency, the cooling duct
is provided with low density cooling fins which form the cooled
side of an air-to-air or a liquid-to-air exchanger. The other side
of the heat exchanger receives heat dissipated by the equipment to
be cooled via an air or liquid circulation loop.
[0018] Advantageous applications of the present invention include
use with aircraft external electronic pods while flying at moderate
to high subsonic through supersonic speeds. The aircraft will
benefit by way of increased aircraft speed and/or range from
reduced drag both while extracting power from the air stream and
during the non-operating mode. The air turbine of the present
invention results in a smaller maximum external diameter than
present external bladed systems for a given level of power
extracted. The ram air turbine of the present invention may be used
in external aircraft stores or pods for generating auxiliary or
emergency power to be supplied to the aircraft as needed. The
present invention is applicable to both manned and unmanned
aircraft. Where cooling capability is advantageous or required the
embodiment of the present invention with cooling capability offers
size and weight advantages over present systems which require
separate cooling systems when an external bladed ram air turbine is
used for power generation.
[0019] In military applications where the radar signature is
important, the ram air turbine of this invention offers reduced
signature compared to present external bladed ram air turbine
generators. With an appropriate external fairing, the rotating
turbine of the present invention is not visible from the
outside.
[0020] Still other advantages and benefits of the ram air turbine
of this invention will become apparent in light of the following
description taken in conjunction with the following drawings. It is
to be understood that the foregoing general description and the
following detailed description are exemplary and explanatory but
are not to be restrictive of the invention. The accompanying
drawings, illustrate several embodiments of the invention, with and
without cooling capability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective external view of a ram air turbine
generating device illustrating a first embodiment of this
invention;
[0022] FIG. 2 is a perspective view of the ram air turbine
generating device shown in FIG. 1 with certain parts being cutaway
and others shown in section;
[0023] FIG. 3 is a half cutaway section of the ram air turbine
generating device shown in FIG. 1, showing airflow streamlines and
relative positions of primary internal components with the diffuser
movable centerbody at maximum aft position and the nozzle control
doors at full open position for the design flight condition;
[0024] FIG. 4 is a perspective view of the ram air turbine
generating device shown in FIG. 1, with portions of the flow
control section and flow control mechanisms exploded;
[0025] FIG. 5a is an enlarged perspective view of the nozzle and
control door and associated control mechanisms positioned for
design flight conditions of the ram air turbine generating device
shown in FIG. 1;
[0026] FIG. 5b is an enlarged perspective view of one nozzle and
control door and associated control mechanisms positioned for above
design flight conditions of the ram air turbine generating device
shown in FIG. 1;
[0027] FIG. 6 is a cross section taken along the line 6-6 of FIG. 3
showing the slide mechanism in the longitudinal spars and mating
members from the centerbody/valve tube, which allows the
centerbody/valve tube to slide relative to the longitudinal
spars;
[0028] FIG. 6A is an enlarged partial sectional view of the axial
slots and slide members which assure central positioning of the
valve tube relative to the center flow guide member;
[0029] FIG. 7 is a longitudinal half section, similar to FIG. 3,
showing air flow streamlines and relative positions of the primary
internal components, the moveable centerbody/valve tube being
advanced partially forward and nozzle control doors being partially
closed for a subsonic above design flight condition;
[0030] FIG. 8 is a longitudinal half section, similar to FIG. 3,
showing the shock wave attached to the centerbody nose with an
entrance shock residing at the inlet and the airflow streamlines
and relative positions of the primary internal components, with the
diffuser inlet and nozzle control doors partially closed for a
supersonic above design flight conditions;
[0031] FIG. 9 is a longitudinal half section, similar to FIG. 3,
showing the relative positions of the primary internal components,
with the centerbody/forward valve tube advanced to the maximum
forward position, presenting a clean aerodynamic surface to the
external air stream when power generation is not required;
[0032] FIG. 10 is a functional block diagram of an electronic
control system for controlling the turbine and generator shaft
speed;
[0033] FIG. 11a is a longitudinal half section, similar to FIG. 3,
showing the relative positions of the primary internal components
for an embodiment of this invention with cooling capability;
[0034] FIG. 11b is a longitudinal half section, similar to FIG.
11a, showing the relative position of the internal components for
an embodiment of this invention provided with cooling capacity,
when cooling is required;
[0035] FIG. 12 is a perspective view of a ram air turbine
generating device in accordance with another embodiment of this
invention, with parts being broken away and others shown in
section;
[0036] FIG. 13 is a perspective view of the ram air turbine
generating device of FIG. 12, with portions of the flow control
section and flow control mechanisms exploded;
[0037] FIG. 14a is an enlarged partial sectional view of the ram
air turbine generating device of FIG. 12, showing the nozzle
control mechanism with the nozzle control doors in their fully open
position;
[0038] FIG. 14 is an enlarged partial sectional view, similar to
FIG. 14a, showing the nozzle control mechanism with the nozzle
control doors in their greatest flow restricting position;
[0039] FIG. 15a is a cross-sectional view taken along the line
15-15 in FIG. 12, with the nozzle control doors in their fully open
position; and
[0040] FIG. 15b is a cross-sectional view taken along the line
15-15 in FIG. 12, with the nozzle control doors in their greatest
flow restricting position.
[0041] FIG. 16 is an enlarged partial sectional view of the nozzle
primary and secondary control doors in their fully open position
showing the flanged bushing which secure the primary and secondary
control doors to each other.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0042] Referring initially to FIGS. 1-4, the overall construction
of the ram air turbine generating device 28 in accordance with a
first embodiment of this invention will be described. The device 28
comprises a generally cylindrical external fairing 30 extending
between an inlet passage or diffuser 32 at leading end 34 and an
aft end 36, and having a plurality of exhaust ports 40 proximate
the aft end. The external fairing 30 is mounted to a primary
structure consisting of a plurality of axially spaced
circumferential rings 50 located in the front section of the device
28, and a plurality of axially spaced bulkheads located in the aft
section of the device 28, that are connected by a plurality of
longitudinal spars 96. A centerbody/valve tube 57 is slidably
supported in axial slots 97, best shown in FIGS. 6 and 6a, composed
of linear ball bearing or other suitable slide mechanisms which are
positioned in the inner surface of the longitudinal spars 96 and
which in turn are mated with matching axial slide members 60
mounted to and protruding from the outer surface of the valve tube
part 56 of the centerbody/valve tube 57 into the axial slots
97.
[0043] The centerbody/valve tube 57 consists of a forward
aerodynamically shaped nose end 76 which forms a centerbody in the
air inlet passage 32, with the aft end of the nose end 76 attached
to the cylindrical valve tube 56, which is larger in diameter than
the aft part of the nose end 76, by a plurality of aerodynamically
shaped radial vanes 78. A cylindrical center flow guide member 42
is coaxial with the valve tube 56 and is of the same external
diameter as the aft part of the nose end 76 and slidably receives
in its inner bore an underlapping aft part of the nose end 76.
Together with the axial slots 97 and slide members 60, this
construction assures the central positioning of the
centerbody/valve tube 57 relative to the center flow guide member
42 throughout the axial movement of the centerbody/valve tube 57
with respect to the external fairing 30.
[0044] With the nose end 76 positioned in the maximum aft position
(position 1), its forward end is in line with the leading edge 34
of the fairing 30, and maximum air flow is allowed through the
circular cross section of the inlet passage or diffuser 32, through
an annular variable area nozzle 68 defined between the inner
surface of the valve tube 56 and the outer surface of the center
flow guide member 42, through a plurality of stator vanes 80 which
are mounted circumferentially on the central flow guide member 42
immediately downstream of the variable area nozzle 68, through a
turbine wheel 62, turned outward by the exhaust flow deflector 90,
and then out to the surrounding region through the aft internal
exhaust ports 40 and the aft external exhaust ports 40.
[0045] A plurality of nozzle control door members 55 are positioned
intermediate the valve tube 56 and the central flow guide member 42
and are operable to control the exhaust area of the nozzle 68 in
response to movement of the valve tube 56 between positions 1 and 2
when full power output is required and between positions 2 and 3
when reduced power, down to fully ceased power, is desired.
Embodiments of the invention using either a DC generator
(alternator) or an AC generator can provide reduced power output
when the electrical load is reduced below full power requirements
by automatically positioning the valve tube 56 between positions 2
and 3 to maintain constant turbine and generator speed while
reducing the generator field voltage and current to maintain
constant generator output voltage at reduced load.
[0046] The nozzle control members 55 include circumferentially
spaced control doors 70 pivotally mounted to side walls 82 of
nozzle 68 for movement between a retracted position, substantially
contiguous with the inner surface of the valve tube 56, and an
extended position wherein they extend into the annular nozzle 68
toward the center flow guide member 42.
[0047] The control doors 70 are moved between the retracted and
extended positions by a plurality of dual nozzle door control cams
115 mounted to the inside surface of the valve tube 56 and pairs of
cam follower 116 mechanisms mounted to the side walls of the
control doors 70 opposite the doors' pivot points 120. By reason of
these and associated mechanisms, each of the control doors 70 is
held in the retracted or open position when the valve tube 56 is in
the first position and in the extended position when the valve tube
is in the second position in a manner which will be more fully
described below.
[0048] FIG. 3 shows the air flow field streamlines and the relative
positions of the internal parts corresponding to the first
position, with the inlet and nozzles at their maximum open
positions, which is termed the design flight condition. The design
flight condition corresponds to the flight conditions where the
product of density and velocity cubed, which is equal to the fluid
dynamic power per unit area available in the air stream is at the
minimum, and where full required power is to be generated. This
condition would map into a minimum flight speed versus altitude
curve where full power output is required. Two typical points on
the design condition curve are Mach=0.80 at 37,000 ft. and
Mach=0.45 at sea level. At flight speeds above the design condition
at any altitude, excess fluid dynamic power is available in the air
stream, and the system automatically adjusts the diffuser inlet
area and nozzle exhaust area to efficiently, and with minimum drag,
maintain design values of turbine and generator speed and power
output in a manner described in more detail below.
[0049] Referring again to FIG. 3, as the air enters and flows
through the inlet diffuser 32, the expanding flow area causes the
air flow to decelerate, with the air stream recovering part of its
kinetic energy in increased internal energy and pressure. This
process is continued as airflow further decelerates while flowing
through an expanding annular channel 48 between the inner wall of
the fairing 30 and the outer wall of the center guide tube 42. The
air flow then enters the plurality of variable area nozzle passages
68 formed between the inner wall of the centerbody/valve tube 57
and the central flow guide 42. Flow is re-accelerated in the nozzle
passages 68, as the flow area is again reduced.
[0050] The air flow control section including the nozzles 68,
control doors 70, and the nozzle door control members 55 are best
seen in FIG. 4, with one door 70 and an adjacent cam 115 shown in
an exploded view for clarity. The dual track nozzle door control
cam 115, with the cam track activation surface 125 facing radially
inward, is attached to the inner surface of the valve tube 56,
which is removed in this region for clarity. Each dual track nozzle
door control cam 115 is positioned in the space provided between
two adjacent nozzle side walls 82. Each pair of nozzle side walls
82 forming a variable area nozzle passage 68 are parallel to each
other and are attached to the center flow guide 42. They extend
within a small distance of the inner surface of the aft cylindrical
valve tube 56 of the centerbody/valve tube 57.
[0051] In FIG. 4, and in the enlarged perspective of FIG. 5a, the
relative positions of the door and control mechanisms for position
1 of the centerbody/valve tube 57, with the doors fully open, are
shown. The actuation surface of the nozzle door control cams 115
contacts door cam followers 116, with the contact force provided by
torsion springs 124 and internal aerodynamic exerting outward
forces on the cam follower shafts 118. The door cam follower shafts
118 extend through slots 117 outboard of the nozzle side walls 82
to accommodate their motion as they are activated by the nozzle
door control cams. They are engaged by one end of the torsion
spring 124 mounted on the outboard side of the nozzle side walls
82. The cam follower shafts 118 are in turn connected to the side
of nozzle control doors 70 mid span along the doors length through
bearings 122 and the doors are pivotally mounted at their forward
side to bearings 120 provided near the top of the side walls 82 of
the nozzle.
[0052] FIG. 5b shows the relative position of the door and control
mechanisms for position 2, that is, the minimum nozzle area for
full power generation at the maximum above design flight
conditions. The nozzle door control cam 115 which is attached to
the aft part of the valve tube 56, which is removed for clarity,
has moved forward with the forward motion of the valve tube 56. The
door is pivoted downward by acting against the cam follower 115
attached to the side of the door 70, moving against the internal
aerodynamic forces in the nozzle 68 and the upward force of torsion
spring 124.
[0053] The cross sectional view of FIG. 7 shows the air flow stream
lines and the relative position of internal parts for above design
flight conditions and for subsonic flight, where the available
power in the air stream is greater than that required to meet
design power requirements. That is, the nozzle has been partially
closed as shown in FIG. 4. The minimum area of the nozzle exhaust
is designed to accommodate the complete range of flight operational
requirements in the intended aircraft applications. For example,
assume the design condition is for Mach=0.80 (776 ft./sec.) at
37,000 ft. If the aircraft had a sea level speed capability up to
the same speed of 776 ft./sec. (Mach=0.69) at sea level, since the
air density and therefore the fluid dynamic power available per
unit area is four times greater, the ram air turbine device of this
invention is designed to be capable of reducing the inlet area and
nozzle area to at least one fourth of the maximum area. If the
flight speed is increased to Mach=1.6 or twice the design speed,
the fluid dynamic power is proportional to the speed cubed and
reduction in area to one eighth would be required. In general, all
combinations of altitude and corresponding maximum speed for the
potential aircraft application would be accounted for in
determining the maximum nozzle area ratio reduction.
[0054] The nozzle control door cam 115 profile, which allows the
maximum nozzle opening at position 1, has a geometric contour
defined so that for each position forward of position 1 toward
position 2, at which point the doors are closed to their maximum
full power operating extent, the ratio of the total exhaust areas
of the nozzles to inlet area of the diffuser is maintained
constant. Referring again to FIG. 3, the center flow guide member
42 is supported at the aft end by a bulkhead 84 which has a
plurality of radial spars 86 forming part of stator 81 and
extending from the inner diameter of the stator 81 to a stator and
turbine casing ring 86 enclosing the stator 81 and turbine wheel
62. The stator and turbine encasing ring 86 is, in turn, attached
to the longitudinal spars 96 of the primary structure. In the
embodiment as shown, the leading edge of each adjacent pair of
nozzle side walls 82, which enclose the cam 115 and associated
mechanisms, has a front nose enclosed with an aerodynamically
shaped leading edge 105, to minimize drag as shown in FIG. 4. The
nozzle control doors 70 are spaced between the nozzle side walls
82, and seals (not shown) on the edge of the control doors mate
with the nozzle side walls 82 to minimize leakage.
[0055] Referring again to FIG. 3 which shows the location of the
primary internal parts under design conditions, after exiting the
plurality of annular nozzle exhausts, the air stream then flows
fully through a plurality of fixed stator blades 80 which turn the
flow in the direction of rotation of the turbine wheel 62 at an
optimum angle from the turbine axis for the particular turbine
design and turbine/generator design speed and a flight speed or
flight speed range where maximum efficiency is desired. Usually the
stator blades 80, blades of turbine wheel 62 and the
turbine/generator rotating speed will be designed to provide the
highest efficiency under conditions where the aircraft will operate
most of the time, for example about Mach=0.80 and 37,000 feet for
many jet aircraft.
[0056] For above design flight conditions, the features which
reduce the nozzle area in proportion with air inlet area will allow
maintenance of the ratio of air flow velocities to the blade inlet
turbine at close to the ratio of the flight speeds. Use of pure
impulse turbine blades rotating at a constant turbine and generator
shaft speed will provide high efficiency through the range of
stator air outlet velocities/turbine inlet velocities of about 25
percent above or below design conditions. Therefore desirable
turbine efficiency will be achievable for this example at flight
speeds of 0.80 Mach +25 percent or between Mach=0.60 and Mach=1.00
or greater at 37,000 ft. altitude. This corresponds to Mach=0.50 at
sea level with the sonic velocity being 20 percent greater than the
sonic velocity at design altitude. High turbine efficiency is
maintained in the transonic through supersonic region as will be
explained while viewing FIG. 8. In transonic and supersonic flight,
a conical shock wave 150 will be attached to the nose of the
centerbody, and the flow will be deflected outward into a conical
flow field with the downstream Mach number less than the free
stream Mach number. The flow will then enter inlet 32 through an
entrance normal shock wave 155 which will reside at the inlet or
slightly in front of the inlet, with the resulting subsonic
downstream flow, entering through the diffuser, initially slowing
down and then accelerating in the nozzle passages 68. With the
nozzle exhaust area adjusted by the cams to be equal to a fixed
ratio of the diffuser inlet area for every position, and with the
nozzle in a fixed or converging configuration at transonic or
supersonic flight speeds, the exhaust will be choked, thereby
limiting the exhaust to a maximum Mach=1.0 throughout the transonic
through supersonic flight region. This ensures that maximum turbine
entrance velocity will be limited to a maximum of no more than 25
percent greater than turbine entrance velocity under Mach=0.80
design conditions, thus ensuring high turbine efficiency through
out the transonic and supersonic flight regime.
[0057] In some applications, high power output and high efficiency
would be desirable through a broader minimum operating range, i.e.,
from low altitudes for speeds down to Mach=0.40 at sea level up to
supersonic values at 37,000 ft for example. In accounting for the
variation in velocity of sound with local air temperature, the sea
level flight Mach=0.40 condition would represent a relative air
speed of 463 feet/second, versus 970 ft/second at the Mach=1.00
through supersonic at 37,000 ft under standard day temperature
conditions for both altitudes. For a given stator exhaust
inclination angle to the turbine axis, optimal turbine efficiency
is obtained by operating the turbine blade at a speed with a fixed
ratio of the stator exhaust speed velocity. Therefore by choosing
the mid point in speed, i.e., at 716 ft/sec for the design point,
the low speed and high speed operating points would be as much as
35 percent above and below the design point. With use of pure
impulse turbine blade, the fall off in turbine efficiency would be
greater than 20 percent and therefore excessive for this wide
velocity range. By using a turbine blade design with some reaction
capability, the falloff in efficiency through this wide air speed
range will be limited to substantially lower values. The reaction
blade turbine recovers part of the air streams kinetic energy by
accelerating the flow in the channels between the blades which
reduce in area along the flow path thereby acting as nozzles. In
pure impulse blades all of the acceleration takes place prior to
entrance in the stator channels, which act like nozzles. The air
stream enters and leaves the turbine flow channel at the same
velocity, while imparting force and performing work on the blades,
purely by forces generated by momentum change results from the
change in flow direction acting on the moving blades, thereby
performing work and generating power. To implement the turbine
reaction capability in a variation of the present embodiment of the
invention, for cases where a wider speed variation with higher
efficiency is desired, the inlet flow would be expanded to a great
extent in the diffuser, thus allowing more of the total pressure
recovery, by allowing part of flow acceleration to occur in the
blade passages. The turbine operates at a higher speed to achieve
this advantage. Design of stator and turbine combinations to
achieve the desired performance over an available inlet pressure
range is a well established discipline.
[0058] After extracting a portion of the fluid dynamic energy from
the air stream flow through the turbine, the flow is turned
outward, with low turbulence, by the aft flow deflectors 90, to
flow through the aft exhaust ports 40, into the external air
stream. The exhaust air is cooled by the turbine expansion process.
A portion of the cooled exhaust air is directed through generator
cooling ducts 94, which indirectly cool the generator via
conduction if desired, or directly using blast cooling with the
generator enclosed (not shown) in the aft end with final cooling
air exhaust ports (not shown) or is accommodated by a nose cavity
of a pod.
[0059] The centerbody/forward valve tube 57 is driven forward and
backward through an actuator shaft 104 by a conventional linear
electro-mechanical or electro-hydraulic actuator 101, which is
positioned inside of the centerbody flow guide 42 as shown in FIGS.
3 and 7. The actuator is fixed on the aft end to a hub in the
bulkhead 84 in a clevis type mounting. The forward end is attached
by a clevis type mounting to the actuator shaft 104. Motion of
actuator 101 is activated by an electronic speed controller 108 in
response to a turbine/generator speed sensor 107 which is mounted
to the turbine/generator shaft 160. FIG. 10 shows a functional
schematic diagram of the electronic controller for the present
embodiment.
[0060] Referring to FIG. 10, the electronic speed sensor consists
of a rotating slotted disk 110 mounted with a central hub to
turbine and generator shaft 60. A light emitting diode 121 and
photo sensitive transistor 123, together termed the speed sensor
107, are mounted to a bracket 112 with the slotted disk 110
positioned intermediate between the diode and the transistor. As
the slotted disk 110 rotates, the light beam to the photo
transistor is interrupted producing a series of electronic pulses
as the photo transistor is turned on and off. A frequency to
voltage converter 133 (a standard converter using standard
integrated circuit technology) converts the series of pulses into a
DC output voltage B which is proportional to the frequency of the
pulses. A digitally programmable voltage reference source 132,
consists of a DC voltage source and a digitally controlled
potentiometer of standard technology. The voltage reference output
A of source 132 corresponds to a desired turbine/generator speed. A
switched mode controller 134 is configured to produce a two phase
series of pulses at a constant frequency, the pulse width being
determined by the difference between the reference voltage A and
the frequency to voltage converter output voltage B. The pulse
widths of the A and B output of the switched mode controller 134
are inversely proportional. The A and B outputs of the switch mode
controller 134 are connected to a two phase power amplifier 136,
also of standard technology, which is used to increase the power
level of the pulses to levels required to drive a DC motor in the
linear actuator. If the reference voltage A and the frequency to
voltage converter output voltage B are equal, the pulse widths of
the A output and the B output of switched mode controller 134 will
cancel, thereby providing no net field EMF and rotational torque to
the actuator motor 101. If pulse width output A is greater than
pulse width B, i.e., the reference voltage A is greater than the
frequency converter output B, the rotational speed of the turbine
generator is less than the design speed by the set tolerance and
the actuator motor will be powered to rotate, and thereby move, via
a ball screw mechanism, centerbody/valve tube 57 aftward toward
position 1, to further open the air inlet and nozzles to maintain
the turbine/generator within the desired speed range. If the
opposite condition exists, i.e., the frequency converter output B
is greater, the motor will be turned in the opposite direction,
moving the centerbody/valve tube 57 toward position 2, closing the
inlet and nozzles to reduce speed. In a preferred embodiment, for
high reliability, a ball screw or electro-hydraulic mechanism is
chosen for the actuator 101.
[0061] A generator 58 is positioned as shown in FIGS. 1, 2, 3, 7,
8, and 9 mounted to an aft bulkhead 88 with shaft 60 extending
through a hole in aft bulkhead 88. The shaft 60 is attached to a
shaft coupler 130 to accommodate any misalignment between the
turbine and generator shaft. The shaft 60 then passes through the
hub of the slotted disk 110, through the turbine wheel hub where
attachment is made to the turbine wheel. The end of the shaft 60
forward of the turbine 62 then passes through a forward bearing
which is located in the axial center hole of the aft bulkhead 84 of
central flow guide member 42.
[0062] FIGS. 11a and 11b show a first alternate embodiment of the
invention where the cooling capability of the invention is
utilized. When cooling effects are needed, for example in the case
of electronic systems powered by the ram air turbine generator,
exhaust air from the turbine may be directed through a heat
exchanger. When cooling effects are not needed the cooled turbine
exhaust air will be ducted directly to the outside as shown in FIG.
11a. When cooling effects are needed a conventional thermostat (not
shown) which is mounted to and senses the temperature of the
equipment to be cooled will trigger a conventional actuator 142 to
close the bypass exhaust valve 140 as shown in FIG. 11b, forcing
the cooled turbine exhaust air through a cooling duct 144. An array
of low density cooling fins are positioned in the cooling duct,
with maximum allowable spacing to maintain low turbine back
pressure and high turbine efficiency. High speed air flow through
the duct will ensure high heat transfer efficiency for each cooling
fin and the cooled side of the heat exchanger. Heat from the
equipment to be cooled will be removed from the equipment and
circulated through the hot side of the heat exchanger using
conventional air or liquid circulation methods.
[0063] A second embodiment of the nozzle and nozzle control
mechanism is shown in FIGS. 12, 13, 14a, 14b, 15a, and 15b. This
embodiment utilizes an annular nozzle 272 including interleaved
panels. The annular nozzle operates by contracting uniformly around
center flow guide 42 to restrict flow between through the space
between annular nozzle 272 and center flow guide 42. Referring
first to FIG. 12 and FIGS. 14a and 14b. A plurality of active
interleaved nozzle control panels 270 and 271 are connected to each
other at their forward and aft ends by bushings 275, which are
flanged at each end. One flange of each bushing 275 is secured to
the radially inner surface of the radially inner primary doors 270.
The shafts of the bushings protrude through slotted holes 276 in
the secondary doors 271, with the other flanges of the bushings
being on the radially outer side of the secondary panels 271. The
flanged bushings 275 hold the primary and secondary panels within a
predetermined distance of each other while the primary panels, and
therefore the secondary panels, are opened and closed by virtue of
the mechanisms which will now be described.
[0064] A ramped slotted linkage 215 is attached to each of primary
panels 270 along the centerline of the panel outer surface. The
forward end of each slotted linkage is pivotally mounted by pinned
holes 220 to a panel mounting structure 280 which extends radially
inward and aft of annular panel mounting ring 290. FIG. 14a shows a
primary panel 270 in maximum open position. A cam follower mounting
plate 217 attached to the inner surface of the aft valve tube 57
pivotally mounts a cam follower 216, which in turn is engaged in a
slotted hole 230 in the slotted linkage 215.
[0065] As the aft valve tube 57 is advanced forward relative to the
position of FIG. 14a, the cam follower 216, which is maintained at
a fixed radial position for all axial positions, by virtue of the
incline of the slotted hole 230 in the slotted linkage 215 causes
the slotted linkage 215 and attached primary panel 270 to rotate
clockwise about the pinned hole 220 and reacting against the
internal aerodynamic forces induced as the air flow is deflected
downward.
[0066] FIG. 14b shows the relative position of the nozzle control
components for the maximum closed position of the nozzle. During
the forward motion of the valve tube 57, the valve tube slides over
the outer surface of the annular panel mounting ring 290, with a
seal means (not shown) located in a groove in the annular mounting
ring 290. The annular mounting ring 290 is attached to the center
flow guide 42 by means of a plurality of aerodynamic shaped radial
spars 291 as shown in FIGS. 15a and 15b. This embodiment of the
invention provides for less flow blockage to the stator and turbine
than the previously described segmented nozzle embodiment. Movement
of the valve tube 57 is controlled by an actuator 101 and an
electronic controller as in the previously described
embodiment.
[0067] The ramped slotted linkage 215 profile, which allows the
maximum nozzle opening at position 1, has a geometric contour
defined so that for each position forward of position 1 toward
position 2, at which point the interleaved panels of annular nozzle
272 are closed to their maximum full power operating extent, the
ratio of the exhaust area of the annular nozzle to inlet area of
the diffuser is maintained constant.
[0068] While a preferred embodiment of the invention has been
disclosed in detail, it should be understood by those skilled in
the art that various modifications can be made to the illustrated
embodiment without departing from the scope of the invention as
described in the specification and hereafter defined in the
appended claims.
* * * * *