Accession Number : AD0839722

Title :   CONTRIBUTION TO RESEARCH ON LOSSES IN THE AXIAL FLOW COMPRESSOR STAGE AT TRANSONIC VELOCITIES (PPISPEVEK K VYZKUMU ZTRAT PRI PROUDENI STUPNEM OSOVEHO KOMPRESORU PRI TRANSSONICKYCH RYCHLOSTECH),

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OH

Personal Author(s) : Klimes, F.

Report Date : 11 JAN 1968

Pagination or Media Count : 14

Abstract : Trends in designing axial-flow compressors, particularly for aircraft, are described as aimed at increasing air stream volume and compression in each stage while reducing blade face area and overall weight. This involves reducing the number of stages and raising their average load, which depend upon intake rates, revolutions, axial velocity and efficiency at Mach speeds. The second half of the paper is devoted to tests on an experimental single-stage compressor fitted with a flexible intake nozzle adjustable to attain varying air flow velocities in the Mach range. Behind this nozzle are upper and lower perforated walls with gauges to measure volume and velocity of escaping air while regulating air flow to a double bank of blades on the rotor. Graphs present gauged pressures before and behind the blades, Mach figures for air velocity before and behind them, and pressure loss in relation to velocity, all recorded at a specific angle of attack on the blades. Shadow or shielded photographs indicate air currents and shock waves formed at blade edges at various Mach velocities. These test blades were made at translucent plastic material and show internal stress at certain points. A 'comb' of pressure sondes is shown behind the cascade, as well as shock-wave interaction at the channel wall. It is concluded that further study of shock waves at blade edges and of air currents between blades will be necessary before attempting higher Mach velocities in the effort to reduce pressure loss to a minimum. (Author)

Descriptors :   (*AXIAL FLOW COMPRESSORS, TRANSONIC CHARACTERISTICS), AXIAL FLOW COMPRESSOR BLADES, PERFORMANCE(ENGINEERING), NOZZLES, ANGLE OF ATTACK, SHOCK WAVES, REDUCTION, CZECHOSLOVAKIA.

Subject Categories : Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE