IMPELLER OF AXIAL-FLOW FAN OR COMPRESSOR Russian patent published in 2002 - IPC

FIELD: aircraft engines. SUBSTANCE: invention can be used in high-speed axial-flow fans and compressors of aircraft engines. With impeller rotating at high speed, supersonic flow with high Mach numbers gets onto leading edge 3 of blade 1 at relative motion increasing from bushing 18 to periphery 14. Owing to the fact that suction surface of blade 1 coincides with skeleton surface of blade 1 and body form of blade 1 is made owing to separation of compression surface from skeleton surface, edge oblique shock wave is formed in inter-blade channel stretching from leading edge 3 to suction surface of preceding blade 1. Use of small angles of wedge profile in cross-section of blade 1 within 3 and 8 deg provides more flat oblique shock wave and, consequently, lower losses. Selection of minimum possible angle of wedge profile equal over entire blade 1 provides forming of most flat edge shock wave over entire blade. Flow velocity decreases directly behind edge shock wave remaining still supersonic at relative motion. Owing to the fact that line of compression surface of profile in cross section of blade 1 is formed by two cubic parabolas connected in place of location of maximum thickness of profile and provided with bending points, second terminal oblique shock wave is formed in outlet section of inter-blade channel behind which flow velocity becomes subsonic. Owing to organization of braking of supersonic flow with high Mach number in inter-blade channel of impeller in system of two oblique shock waves, and not in one normal shock wave, process takes place at decreased losses, thus increasing efficiency of impeller, especially in peripheral area of blade 1. Owing to the fact that in proposed impeller on its periphery ratio of chord of profile of blade 1 to pitch of cascades should be not smaller than value found from equation , conditions are provided at which edge and terminal shock waves do not merge into one normal shock wave on suction surface of preceding blade, even on periphery 14 of blade 1, where distance between edge and terminal shock waves is minimum. EFFECT: enhanced operation reliability. 4 dwg