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Particle separator for engine air inlets
US3521431A
United States
- Inventor
Harold D Connors Fred D Buckley - Current Assignee
- Avco Corp
Worldwide applications
1969
US
Application US819892A events
1969-04-28
1970-07-21
Application granted
1970-07-21
1987-07-21
Anticipated expiration
Status
Expired - Lifetime
Description
translated from
July 21, 1970 H. D. CONNORS ETAL PARTICLE SEPARATOR FOR ENGINE AIR INLETS 2 sheets-sheet 1 Filed April 28, 1969 1N VENTORS.
S S Y m M Y NL 0 mm MW ULA D flu DD L OD MM HF 6 Y B July 21, 1970 H. D. CONNORS ETAL 3,521,431
PARTICLE SEPARATOR FOR ENGINE AIR mums Filed April 28, 1969 2 Sheets-Sheet 2 I I l I I l -.-I I
. S SS ,Y RR I E OO 2N N R NNL #0 WO T C C .T I w 6 D f w DD L 0D RE m Y B r m. 0 2
United States Patent 3,521,431 PARTICLE SEPARATOR FOR ENGINE AIR INLETS Harold D. Connors and Fred D. Buckley, Milford, Conn.,
assignors to Avco Corporation, Stratford, Conn., a corporation of Delaware Filed Apr. 28, 1969, Ser. No. 819,892 Int. Cl. B01d 45/12 US. Cl. 55-306 ABSTRACT OF THE DISCLOSURE An apparatus to separate and remove foreign particles from the air supply to gas turbine engines is disclosed. The contaminated air is drawn through first and second centrifugal separating stations during which centrifugal forces act on the particles. The particle contaminants and carrier air from the second separating station are transmitted to a tertiary separating station to be again cleaned. Cleaned air from each of the separating stations returns to the engine inlet. Particle contaminants from the tertiary station are removed from the system and may be ejected from the separator.
BACKGROUND OF THE INVENTION This invention relates to a particle separator for use adjacent the air inlet of a gas turbine engine to remove foreign matter such as sand and dust from the air stream.
Air craft turbine engines are particularly susceptible to damage from foreign objects introduced into the air intake stream of the gas turbine engines. Stones, gravel and other foreign matter drawn into the air stream often rupture, distort, and damage blades and other component parts of the engine. These particles, which individually have little effect on the engine, can cause very substantial damage when introduced into the engine in large quantities. For example, it has been found that the engine of a helicopter operating at low altitude in a desert environment can lose performance due to erosion of engine blading by high velocity sand particles. In addition, the desired balanced condition of the compressor is often disrupted and the useful life of the engine shortened, if it is not completely destroyed.
The importance of removing small foreign particles, such as sand and dust, has long been recognized. Many mechanisms for accomplishing this purpose are known in the art. One example is the separator shown in US. Pat. 3,371,471 to H. D. Connors. However, the present invention provides certain improvements recognized as important. Some improvements and advantages of the present invention are the self-cleaning capability, minimal maintenance requirements, compact, lightweight, accessibility, small volume, low pressure loss, small amount of power required to eject contaminant and effectiveness over a broad range of particle size from full design flow to V2 flow.
Accordingly, it is an object of this invention to provide a lightweight and compact separator for effectively removing particles from the air stream supplied to a gas turbine engine.
3 Claims I PatentedJuly 21, 1970 "ice A further object of this invention is to provide a sepa rator with the above-mentioned advantages.
SUMMARY OF THE INVENTION This invention provides an improved particle separator for removing particles from the stream of air supplied to the inlet of a gas turbine engine. The particle separator utilizes centrifugal forces acting on the particles in the first two separating stations to separate the particles from the stream of air. Air cleaned from the second separating station is in communication with the main air stream and is returned therein upstream of the engine air inlet. A tertiary air cleaning station is used for final cleaning and removal of the particle contaminant.
Other details, uses, and advantages of this invention will become apparent as the following description of the exemplary embodiment thereof presented in the accompanying drawings proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show present exemplary embodiments of this invention in which:
FIG. 1 is alongitudinal cross-section taken substantially on a section through the separator assembly in a vertical plane and showing'the longitudinal axis of rotation of the power shaft of the engine extending forward of the annular air inlet to the engine;
FIG. 2 is an enlarged diagrammatic representation showing the first and second separating stations; and
FIG. 3 is a cross-sectional view, not to scale, taken on the line 3-3 of FIG. 1.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT Reference is now made to FIG. 1 which illustrates one exemplary embodiment of the improved particle separator of this invention, which is designated generally by the reference numeral 10. The separator assembly 10 is designed for mounting on the front of a gas turbine 12, having an annular air inlet 14 and a forwardly extending gear case 16 and propeller or power shaft 18. The forwardly extending power shaft 18 may not be present in the purely jet-type engine, but would be present in a socalled turbos'haft-type gas turbine engine of the present exemplary embodiment.
The specific structure illustrated in FIG. 1 is a crosssection of an annular separator assembly 10 with the longitudinal axis of the shaft 18 or the axis of the engine as a center. The first centrifugal separating station, shown generally at 11, is of a radial inflow bellmouth form having an annular air inlet 20 extending from an outward region in a generally radial inward direction with an outer curved wall 22 and an inner curved wall 24. The annular member 22 terminates closely adjacent to an annular curved deflector element or wall 26. The inner curved wall 22 is of such configuration, bending in a curved direction toward the air inlet 14 so that air entering in a radial direction into the inlet 20 will be caused to move in a curved path and any particles heavier than air will be thrown by centrifugal force and flow direction to impinge upon the wall .22 during the curved air movement and particles so impinging will be deflected and intercepted by wall 26. Side splitter vanes 23 may be mounted in inlet 20 to prevent a tangential particle path 3 and to guide the particles to improve the separator effectiveness.
The deflector wall 26 forms the outer wall of a second centrifugal separating station designated generally as 28. Passages 27 and 29 form the outlets for the second separating station 28. Passage 27 is an inner annulus and is in communication with a teritary or third separating station 34. Passage 29 is a clean air passage for removing cleaned air, sometimes called the secondary air stream, from the second separating station. The wall 26 is formed so that an extension of the wall provides a secondary air passage 31 which is in communication with passage 29. Thus, clean air from the second separating station can be reinserted into the main air stream upstream of air inlet 14 and downstream of the inlet 20 of the first separating station.
As best seen in the diagrammatic representation of FIG. 2, air having particles shown generally as 30 entrained therein is drawn into the first separating station inlet 20. This air, generally represented by dashed arrows, is drawn through a turn during which time, because of the centrifugal forces acting on the particles, the particles 30 are cast onto the outer flow wall 22 while the clean air, or the main air stream is drawn into the engine inlet 14. It has been found that approximately 90% of the air is drawn into the engine inlet passage while of the air enters the second separating station as carrier or transport air. The particles 30, carried by the small amount of transport air, are caught by the deflector wall 26 and turned into the second separating station 28. The particles are then centrifugally thrown toward the curved annulus 32, forming a part of the second separating station 28 and deflector element 26. In this second centrifugal separating station, approximately 90% of the carrier air, which is 10% of the main air stream, will be drawn off through passage 29 as clean air and the remaining 10% of the carrier air or equivalent to approximately 1% of the main air stream becomes the carrier air for particles 30 to be transmitted through passage 27 to the third separating station. The clean air from the second separating station or secondary air stream is inserted into the main air stream through passage 31.
Particles from separating station 28 are transmitted through passage 27 and inlet 33 to a third separating station which is best seen in FIGS. 1 and 3. The third separating station, shown generally as 34, comprises a plurality of cyclonic or vortex type separator tubes 36 mounted in a chamber 35. The operation of the cyclonic separators 36 are such that, as an example, the particleladen air is admitted past inclined guide blades or through a tangential inlet into a chamber, called a cyclone chamber, whereby the air is set spinning therein and by the centrifugal force thus engendered, concentrates the particles toward the periphery of the cyclone chamber. The concentrated particles are discharged at the periphery of each cyclone chamber to a collection area 38 and the particle-free air passes on straight through the cyclone separator to a clean air chamber 39 and through exit 40 into the secondary air stream which is in communication with the secondary air passage 31. Hence, both the secondary and tertiary cleaned air reenters the main air stream from passage 31.
The concentrated particles 30 are accumulated in area 38 and ejected overboard through an ejector 42. The ejection may be a continuous operation or intermittent as the design dictates. In the illustrative embodiment shown, air from the engine bleed is connected at 44, to provide the motive power for ejection of the contaminant overboard. It is noted that the air required for the ejector power may be supplied either from the engine bleed or from an auxiliary pump. It is also noted that the velocity head at the engine inlet is used to provide the motive power for movement of the contaminant particles and carrier air.
It is noted also that in the preferred form of the invention shown the parts are annular to conform to the engine inlet position and configuration, although important features of the invention could be accomplished by rectangular or other shaped parts having substantially the same general cross-section as shown.
It can be seen that this invention presents advantages not heretofore incorporated in separators for gas turbine engines. Less than 0.1% of the initial main air stream is lost in cleaning steps. Thus, this invention provides a separator which is of simple and economical construction, is compact and provides for minimal maintenance.
While a present exemplary embodiment of this invention has been illustrated and described it will be recognized that this invention may be otherwise variously embodied and practiced by those skilled in the art.
What is claimed is:
1. A particle separator for removing particles from a stream of air supplied to the inlet of a gas turbine engine, said separator comprising:
a first centrifugal separating station upstream of the inlet having inner and outer curved walls wherein centrifugal force causes particles and transport air to travel along the outer wall and the cleaned main air stream passes to the inlet;
a second centrifugal separating station in series communication with said first station to receive the particles and transport air from said outer wall, said second station forming a secondary air passage in communication with the main air stream downstream of the first station inlet and upstream of the inlet wherein clean air from said second separating station is inserted into the main air stream,
a third separating station in series communication with said second separating station for receiving particles and transport air from said second separating station, said third separating station comprising a plurality of cyclonic tube separators for further separating particles from the transport air, each cyclonic tube having a clean air outlet in communication with a clean air chamber in flow communication with said secondary air passage wherein clean" air from said cyclonic tubes is transmitted to said secondary air passage and inserted into the main air stream, and a particle outlet in flow communication with a collecting chamber, and
ejector means in communication with said collecting chamber for ejecting particles from said separator.
2. A particle separator for removing particles from a stream of air supplied to the inlet of a gas turbine engine, said separator comprising:
a first centrifugal separating station comprising an annular radial inflow bellmouth upstream of the inlet having inner and outer curved walls wherein centrifugal force will cause particles in the stream of air to travel along the outer wall;
a second centrifugal separating station in series with said first station, said second station being formed by a curved deflector element spaced from the terminating end of said outer wall, said deflector element forming a secondary air passage in communication with the main air stream downstream of the first station inlet and upstream of the inlet, said deflector element being positioned to intercept and defleet particles into said second separating station, said second separating station being in communication with said secondary air passage wherein clean air from the second separating station is inserted into the main air stream;
a third separating station in series with said second separating station for receiving particles from said second station for final separation of particles from transport air, said third separating station having a clean air passage in flow communication with a clean air chamber, said chamber being in communication with said secondary air passage wherein clean air therefrom is transmitted to said secondary air passage for insertion into the main air stream, and a particle discharge passage in flow communication with a particle collecting chamber, and particle ejector means in communication with said collecting chamber wherein particles are transmitted to the exterior of the separator. 3. A separator as set forth in claim 2 in which said third separating station comprises a plurality of vortex 10 tube separators.
References Cited UNITED STATES PATENTS 3/1968 Connors 55-306 1/1969 Beurer 55306 FRANK W. LU'ITER, Primary Examiner V. GIFFORD, Assistant Examiner
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