Design of Transonic Compressor Cascades for Minimal Shock Losses and Comparison with Test Results,
HOCHSCHULE DER BUNDESWEHR MUNICH (GERMANY F R)
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New blading concepts with respect to optimal profile shape take into account the close interdependence between pressure distribution on profile suction and pressure side and boundary-layer development i.e. losses on these surfaces. For transonic compressor bladings with minimal losses the shock and shockboundary-layer interaction losses have to be carefully considered. For supersonic inlet conditions these losses have been reduced by using wedge-type profile shapes in the supersonic part of the profile. On the other hand, diffusion losses in the subsonic region rear part of the blade can be reduced by reducing subsonic deflection of a given vector triangle, resulting in a limited supersonic expansion. Thus, a very careful optimisation process has to be done for the partition of supersonic and subsonic deflection. Detailed cascade tests were carried out for the mid section of a rotor blade of a three-stage transonic compressor. Analysis of these tests and additional laser anemometry measurements within the compressor showed good agreement between design and test and proved the low loss design of the special profile types.