COMPRESSOR SIDE INLET WITH IMPROVED AERODYNAMIC PERFORMANCE AND REDUCED MANUFACTURING COMPLEXITY

Abstract

An air plenum is configured to direct air into a centrifugal compressor impeller in an ACM compressor. The air inlet plenum has a cylindrical outer wall, a forward circular end wall, and a rearward circular end wall. An air inlet radially extends from the cylindrical outer wall and is in flow communication therewith. An aperture in forward circular end wall is configured to seal receive about a rotating shaft. An aperture in rearward circular end wall is configured to receive the rotating shaft and allow air flow therethrough about the rotating shaft. A rectangular baffle extends radially inward from the cylindrical outer wall at a circumference thereof opposite the air inlet. The rectangular baffle may extend between the forward and rearward end walls.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to compressors, and more specifically to an air inlet system for a centrifugal compressor of an air cycle machine for aircraft environmental control system or a gas turbine engine compressor.

Centrifugal compressors of air cycle machines for aircraft environmental control systems may be mounted on the mid-portion of a rotating shaft between a turbine and a fan. This configuration is commonly referred to as a three-wheel Air Cycle Machine (ACM). It is typical of an ACM that the energy gained in turbine is used to drive a compressor and a fan. All three wheels (turbine, compressor, and fan) may be disposed on a common shaft of an ACM or three-wheel machine. The fan may convey a cooling air stream branched off from ambient air through a cooling shaft in which primary and main heat exchangers may be disposed.

For three-wheel ACMs, the compressor is usually mounted on the mid-portion of the rotating shaft between the turbine and the fan; this typical configuration may result in a geometrically complicated side inlet design. The air inlet may need to first direct the flow radially inward from one side, then split the flow around the rotating shaft towards two sides, and simultaneously turn the flow into an axial direction for entry into an impeller eye of a compressor.

Since a compressor's overall performance may be sensitive to the inlet flow pattern and inlet pressure loss, various inlet plenum configurations such as a double-lobed plenum and array of inlet guide vanes (IGVs) have been used for aircraft environmental control applications. Such a configuration is shown in FIG. 1. Double-lobed plenum 200 has inlet 202 and IGVs 206. IGVs 206 extend in the direction of air flow from inlet 202 to radial outlet 212. Bypass channels 204 may bypass inlet air from radial outlet 212 as shown. Two lobes 208 are in plenum 200 about radial outlet 212 on a side opposite flow inlet 202. Lobes 208 extend inwardly and meet at location 210, proximate radial outlet 212 and opposite inlet 202.

As can be seen, there is a need for minimizing the inlet aerodynamic loss of an inlet plenum and promoting inlet flow uniformity while providing a means to reduce the manufacturing complexity of the plenum for an ACM.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a centrifugal compressor of an ACM for an aircraft environmental control system is provided. The compressor has a rotatable cylindrical shaft with an impeller having blades radially extending outward therefrom. An air inlet plenum has a cylindrical sidewall, a first end wall, and a second end wall. The first end wall has an aperture configured to be substantially sealed about the rotatable cylindrical shaft. The second end wall has an outlet in flow communication with the impeller about the rotatable shaft. An air inlet extends radially outward from the cylindrical sidewall and is in flow communication with the air inlet plenum. A baffle extends radially inward from the cylindrical wall approximately 180° from the air inlet.

In another aspect of the present invention, a centrifugal compressor is provided having a shaft with a longitudinal axis and a gas turbine engine configured to rotate the shaft about the longitudinal axis. The shaft has an impeller with blades extending radially therefrom. An air inlet plenum has a portion about the shaft between the gas turbine engine and the impeller. The air inlet plenum is configured to first direct the flow of inlet air radially inward to the shaft from one side of the shaft and split a portion of the flow of inlet air around the rotating shaft while simultaneously turning the flow of inlet air parallel to the longitudinal axis of said shaft for entry into the impeller. The portion of the plenum about the shaft has a cylindrical outer wall with an air inlet portion extending therefrom in a radial direction from the shaft. A rectangular baffle extends radially inward from the cylindrical outer wall of the plenum toward the shaft. The rectangular baffle is on an opposite side of the cylindrical outer wall than the air inlet portion and extends the cylindrical outer wall in a direction substantially parallel with the longitudinal axis of the shaft.

In yet another aspect of the present invention, an air inlet plenum is provided to direct air into a compressor impeller. The air inlet plenum has a cylindrical outer wall, a first circular end wall, and a second circular end wall. An air inlet radially extends from the cylindrical outer wall and is in flow communication therewith. An aperture in the first circular end wall is configured to sealing receive a rotating shaft. An aperture in the second circular end wall is configured to receive the rotating shaft and allow air flow between the second circular end wall and the rotating shaft. A rectangular baffle extends radially inward from the cylindrical outer wall at a circumference thereof opposite the air inlet. The rectangular baffle extends between the first and second end walls.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective sectional view of an air plenum of the prior art;

FIG. 2 is a schematic sectional view of a centrifugal compressor of an ACM according to an embodiment of the present invention;

FIG. 3 is a perspective sectional view of an aspect of an air plenum according to an embodiment of the present invention;

FIG. 4 is a perspective sectional view of another aspect of an air plenum according to an embodiment of the present invention;

FIG. 5 is a side cross-sectional view of a section of an air plenum according to an embodiment of the present invention showing air flow paths therethrough; and

FIG. 6 is a front cross-sectional view of a section of an air plenum according to an embodiment of the present invention showing air flow paths therethrough.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.

For three-wheel Air Cycle Machines (ACMs), the centrifugal compressor may be mounted on the mid-portion of a rotating shaft between a turbine and an impeller or fan. This configuration may result in a geometrically complicated side inlet design, which may be required to first direct the flow of intake air through an air inlet radially inward from one side and then split the air flow around the rotating shaft and simultaneously turn the air flow to an axial direction for entry into the impeller eye. Since compressor overall performance may be sensitive to the inlet flow pattern and inlet pressure loss, the configuration of an air plenum may be critical. Embodiments of the present invention may provide a means for enhancing the aerodynamic performance of an air delivery system to the impeller without increasing manufacturing complexity and costs.

FIG. 2 shows ACM compressor 100. Rotatable shaft 104 may extend from a forward end 106 to a rearward end 107. A gas turbine engine, not shown, may provide rotational power to shaft 104 at forward end 106. Air plenum 102 is shown having an air inlet 120 in a lower cylindrical portion 122 thereof. The lower cylindrical portion 122 may extend upward to a flared portion 124 of or air inlet 122. Flared portion 124 may extend upward to cylindrical outer wall 132 which may circumscribe shaft 104 proximate impeller 108. Air plenum 102 may have a circular or rounded forward wall 133 which may seal with rotatable shaft 104 enclosing an axial end of cylindrical outer wall 132. Rearward wall 135 may partially enclose the other axial end of cylindrical outer wall 132. Rearward wall 135 has aperture 126, which has a diameter greater than the diameter of rotatable shaft 104 allowing air to exit air plenum 102 and enter impeller 108. Impeller 108 compresses the inlet air which may exit through diffuser 137 to compressor outlet 110. Baffle 130 is shown depending inward from outer wall 132 and may be normal to the axis of compressor 100. Baffle 130 may be comprised of a solid material having no perforations or apertures. Such a configuration may prevent air flowing thereto from flowing around the inner surface of outer wall 132.

FIG. 3 shows a perspective view of air plenum 102. Air plenum 102 is configured to direct air axially about rotatable shaft 104 into compressor impeller 108. Air plenum 102 may have cylindrical outer wall 132 with circular forward wall 133 and circular rearward wall 135 partially enclosing axial ends thereof. An aperture 134 in circular forward wall 133 may be configured to sealing receive rotatable shaft 104. An aperture 126 in rearward circular wall 135 is configured to receive rotatable shaft 104 and has a greater diameter than rotatable shaft 104 to allow air flow between rearward circular wall 135 and rotatable shaft 104. Air inlet 120 radially extends from cylindrical side wall 132 and is in flow communication therewith. Air inlet 120 may have lower cylindrical portion 122 extending upward to flared portion 124 of or air inlet 122. Flared portion 124 may extend upward to cylindrical side wall 132. Rectangular baffle 130 extends radially inward from cylindrical side wall 132 at a circumference thereof opposite or 180° from air inlet 120. Rectangular baffle 130 may extend between and may join circular forward wall 133 and circular rearward wall 135. Advantageously, baffle 130 may extend at least one forth the distance from cylindrical side wall 132 and aperture 134 in forward wall 133.

FIG. 4 shows a perspective view of air plenum 202. Air plenum 202 may have a similar configuration as air plenum 102 and at least one inlet guide vane 136. Guide vane 136 is configured to direct the flow of inlet air radially toward rotatable shaft 104. Guide vane 136 may be in a plane parallel with a plane of baffle 130 and may be substantially within flared portion 124 of air inlet 120.

FIG. 5 shows air flow paths 140 through a side cross-sectional view of air plenum 102. Air enters air plenum 102 through air inlet 120 in a substantially radial orientation with respect to rotatable shaft 104. The air flows upward through lower cylindrical portion 122 and into flared portion 124 of air inlet 120. In flared portion 124 air flow paths 140 begin to diverge toward impeller 108 and about the surface of rotatable shaft 104. Within cylindrical side wall 132, air flows circumferentially about its inner surface toward baffle 130 and axially toward impeller 108. Baffle 130 may prevent the air flow pattern 140 from swirling about the inside surface of cylindrical sidewall 132 of air plenum 102 and force the flow to turn axially with respect to rotatable shaft 104 sooner and enter impeller 108 earlier and thus promote the inlet flow uniformity and reduce the inlet pressure loss. Air flows axially through aperture 226 and into compressor outlet 110. Forward wall 133 may seal the opposite axial end of cylindrical side wall 132 with shaft 104, forcing all inlet air through aperture 126 in rearward wall 135.

FIG. 6 shows air flow paths 140 through a front cross-sectional view of air plenum 102. Air enters air plenum 102 through air inlet 120 in a substantially radial orientation with respect to rotatable shaft 104. The air paths 140 are upward through lower cylindrical portion 122 and into flared portion 124 of air inlet 120. In flared portion 124, air flow paths 140 begin to diverge toward aperture 126 in rearward wall 135 and about the surface of rotatable shaft 104. Within cylindrical side wall 132, air flows circumferentially about its inner surface toward baffle 130 and axially toward aperture 126. Baffle 108 may prevent the air flow pattern 140 from swirling about the inside surface of cylindrical sidewall 132 of air plenum 102 and force the flow to turn axially with respect to rotatable shaft 104 sooner and enter impeller 108 earlier and thus promote the inlet flow uniformity and reduce the inlet pressure loss.

As shown in FIGS. 5 and 6, baffle 130 in cylindrical side wall 132 may reduce pressure loss in air flow 140 as it flows from air inlet 120 and out of aperture 126. Baffle 130 may also improve the flow uniformity of air flow 140 at the plenum exit or the impeller entrance at aperture 126.

Plenum 102 with circular or cylindrical side wall 132 having a single rectangular baffle 130 may be casted easily and baffle 130 may prevent the flow 140 from swirling inside plenum 102 and force the flow to turn axially toward aperture 126 earlier and enter the impeller earlier and thus may promote inlet flow uniformity to the impeller and reduce the inlet pressure loss.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. A compressor comprising:

an impeller;

an air inlet plenum having a sidewall, a first end wall, and a second end wall;

said first end wall having an aperture configured to be substantially sealed about a rotatable shaft;

said second end wall having an outlet in flow communication with said impeller about said rotatable shaft;

an air inlet extending radially outward from said sidewall and being in flow communication with said air inlet plenum; and

a baffle extending radially inward from said sidewall approximately 180° from said air inlet.

2. The compressor of claim 1 wherein said baffle is rectangular.

3. The compressor of claim 1 wherein said baffle is solid.

4. The compressor of claim 1 wherein said baffle extends between said first and said second end walls.

5. The compressor of claim 1 wherein said baffle extends at least one half the distance from said sidewall to said shaft.

6. The compressor of claim 1 wherein said air inlet has at least one guide vane configured to direct the flow of inlet air radially toward said shaft.

7. The compressor of claim 6 wherein said guide vane is in a plane parallel with a plane of said baffle.

8. An air cycle machine compressor comprising:

an air inlet plenum having a portion about a shaft between a gas turbine engine and an impeller;

said air inlet plenum being configured to direct the flow of inlet air radially inward to the shaft from one side of the shaft and split a portion of the flow of inlet air around the rotating shaft while simultaneously turning the flow of inlet air parallel to a longitudinal axis of the shaft for entry into the impeller;

said portion of said plenum about said shaft having a cylindrical outer wall;

said cylindrical outer wall of said air inlet plenum having an air inlet portion extending therefrom in a radial direction from the shaft; and

a rectangular baffle extending radially inward from said cylindrical outer wall of said plenum toward the shaft, said baffle being on an opposite side of said cylindrical outer wall than said air inlet portion and extending said cylindrical outer wall in a direction substantially parallel with the longitudinal axis of the shaft.

9. The air cycle machine compressor of claim 8 further comprising a guide vane in said air inlet portion configured to direct inflowing air radially toward said shaft.

10. The air cycle machine compressor of claim 8 wherein said portion about said shaft has sidewalls radially extending inward from said cylindrical outer wall toward said shaft, said rectangular baffle extends between said sidewalls.

11. The air cycle machine compressor of claim 8 wherein said baffle extends at least one half the distance from said cylindrical outer wall to said shaft.

12. The air cycle machine compressor of claim 8 wherein said portion of said plenum is configured to provide a substantially uniform flow rate of air about the circumference of said shaft for entry into said impeller.

13. An air plenum configured to direct air into a compressor impeller comprising:

a cylindrical outer wall;

a first rounded end wall;

a second rounded end wall;

an air inlet radially extending from said cylindrical outer wall and being in flow communication therewith;

an aperture in said first rounded end wall configured to sealing receive a rotating shaft;

an aperture in said second rounded end wall configured to receive the rotating shaft and allow air flow between said second rounded end wall and the rotating shaft; and

a baffle extending radially inward from said cylindrical outer wall at a circumference thereof opposite said air inlet, said rectangular baffle extending between said first and second end walls.

14. The air plenum of claim 13 wherein said baffle extends at least one half the distance from said cylindrical outer wall to said aperture in said first circular end wall.

15. The air plenum of claim 13 wherein said air inlet has at least one rectangular guide vane in a plane parallel with a plane of said baffle.

16. The air plenum of claim 13 being configured to intake air from said air inlet and supply air to said aperture in said second circular end wall with a substantial even distribution of air flow about a circumference of said aperture in said second side wall.

17. The air plenum of claim 13 wherein said air inlet has a tapered portion radially extending from said cylindrical outer wall and a cylindrical portion extending radially outward from said tapered portion.