US2362514A - Centrifugal compressor - Google Patents

Description

Nov. 14, 1944. D. F. WARNER GENTRIFUGAL coMPREssoR Filed June 5. 1941 Fig Inventor: Donald FT Warner; b Mya/MM y His Attorney.

Patented Nov. 14, 1944 2,382,514 CENTBIFUGAL COMPRESSOR Donald F.

Warner, Swamplcott, Ma., assigner to General Electric Company, a corporation oi' New York Application June 3, 1941, Serial No. 396,426 2 Claims. (Cl. 230-127) The present invention relates to centrifugal compressors or blowers such as are used on aircraft for supplying air or like medium under pressure to a combustion engine or other consumer for air under pressure. More specifically the invention relates to the type of centrifugal compressors which have an impeller with a set of circumferentially spaced blades forming irnpeller passages and a diffuser with a set of vanes forming difluserlmssages for receiving a mediuim impelled by the impeller and for converting part of the velocity energy of such medium into pressure energy. Such compressors, especially when used on aircraft, are operated at high speeds, for example oi the order of i200 feet per second peripheral speed and above. At vsuch high speed the medium forced by the impeller into the diiiuser passages due to the high relative speed between the impeller blades and the diffuser vanes may create considerable vibrations and shocks in these blades and vanes.

The object of my invention is to provide an improved construction and arrangement of centrifugal compressors of the type above speciiled whereby vibrations of the impeller blades and diffuser 'varies are reduced to a. minimum. This is accomplished in accordance with my invention by the provision of impeller blades having `outer portions inclined toward the inner portions of the diiuser vanes. In a preferred embodiment the outlet edges of the impeller blades are inclined toward the inlet edges of the diffuser vanes, and in addition the outlet edges and the adjacent portions of the impeller blades are inclined toward radial planes in one direction, whereas the inlet edges and the adjacent portions oi' the diffuser vanes are inclined toward radial planes in the opposite direction. More generally the blades and varies are inclined in opposite directions toward surfaces through their roots and perpendicular to the plane of rotation.

For a better understanding of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompnyill drawing.

In the drawing, Fig. 1 illustrates a sectional view of a centrifugal compressor embodying my invention; Fig. 2 is a view along line 2-2 of Fig. l; Fig. 3 is a view along lines 2-3 of Fig. 2; and Fig. 4 is a view along line 4-4 of Fig. 3.

The compressor comprises a casing having two halves l0 and Il anged together by moans including a row of bolts i2. A central portion of the casing forms a chamber with an inlet l2 for .receiving air or like medium to be compressed. An impeller il is located in the impeller chamber and has a disc i5 with a plurality of circumi'erentially spaced blades i1 integrally formed thereon for impelling the medium conducted to the inlet Il by forcing such medium radially outward by the action ot centrifugal force. The medium discharged from the outer portion of the impeller is received by a diffuser lli which converts part of the velocity energy of the impelled medium into pressure energy and discharges such medium to a discharge chamber or scroll il formed by an outer portion oi the casing and having a discharge opening 20. The diil'user Il has a wall in the form of a ring 2i supported on and secured to the casing half lil by means including a plurality of bolts 22. A plurality oi vanes 23 are secured to, in the present example integrally formed with. the ring 2| forming with an adjacent portion of the casing wall a plurality of diffuser passages 24.

Each diffuser vane 2l has an inlet edge 25 and eachimpeller blade il has an outlet edge 26. The edges 25 and 28 oi' the diffuser vanes and the impeller blades respectively in accordance with my invention are inclined toward each other. When viewed along line 2-3 of Fig. 2 as illustrated in Fig. 3, the inlet edges 25 oi the diiuser varies are inclined toward the left relative to the axial direction; whereas, the outlet edges 2i of the impeller blades il are inclined toward the right relative to the axial direction. During operation the impeller blades assume diiferent positions relative to the diffuser varas as the impeller is rotated an angle corresponding to the pitch of the diiiuser vane. During such relative movement the flow pattern of the iiuld in the adjacent portions of the impeller passages and the diffuser passages will change. This change in flow conditions is considerably reduced by bevelling the adjacent edges of the impeller and the diuser in opposite directions.

As a further means to reduce vibration in accordance with my invention. I incline adjacent edge portions of the impeller blades and the diiluser vanes in opposite directions toward planes through the root oi such edges and perpendicular to the plane oi rotation. This is indicated in Fig. 2 and illustrated in detail in Fig. 4. The inlet edge of the diffuser vane 23 is inclined toward the leit relative to a plane or surface 2l through its root and perpendicular to a Iplane of rotation 2l, whereas the outlet portion of the adjacent impeller blade Il is inclined toward the right relative to a. plane or surface 30, through the root of the blade and perpendicular to the plane 29. From another viewpoint both the impeller blades and the diffuser vanes, in particular the adjacent portion thereof; that is, the outlet portions of the impeller blades and the inlet portions of the dii'- Iuser vanes, are inclined toward a plane perpendicular to the axis of rotation, the outlet portions of the impeller vanes being inclined toward such plane in one direction and the inlet portions of the diiuser vanes being inclined toward such plane in the opposite direction. With such an arrangement of the adjacent edges and portions of the diluser vanes and the impeller blades, a relatively small and smooth change of the flow pattern takes place as these vanes are moved relative to each other during operation. The fatigue of the vanes heretofore caused by the hammer-blow-like shocks of the compressed medium on the adjacent portions of the diffuser vanes and the impeller blades are materially reduced and the dependability and life of these parts are correspondingly increased. With the improved arrangement oi the inlet and outlet edges of the diffuser and impeller respectively, the rise in temperature of the impeller medium on its passage through the compressor is substantially reduced, and the emciency of the compressor accordingly is increased.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. Centrifugal compressor comprising a casing, an impeller located in the casing and having a plurality of circumferentially spaced blades, a diffuser located in the casing and surrounding the impeller for converting a part of the velocity energy of a medium discharged from the impeller into pressure energy, the diffuser having a plurality of circumferentially spaced vanes, the diiiuser vanes and the impeller blades having adjacent edges bevelled in opposite directions toward the axis of rotation and the diifuser vanes and impeller blades having adjacent `portions inclined in opposite directions with reference to planes through their roots and perpendicular to a plane of rotation.

2. Centrifugal compressor comprising a casing forming an impeller chamber and a diffuser chamber, an impeller with a plurality of circumferentially spaced blades located in the impeller chamber, and a diffuser with a plurality of circumferentially spaced vanes located in the diffuser chamber, the diffuser vanes having inlet portions with a bevelled edge and inclined toward a plane of rotation.

DONALD F. WARNER.

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