Schlieren tests on some conventional turbine cascades

Abstract

Schlieren tests on a series of conventionM turbine cascades have shown that the variations in performance at high speed can be accounted for by shock-wave and boundary-layer interaction. The rise in loss coefficient sometimes encountered at outlet Mach numbers of 0-6 to 0.8 is shown to be due to the formation of a λ-shock series on the upper surface of the blade, the subsequent fall in loss coefficient and increase in deflection as the outlet Mach number rises to unity being caused by the formation Of a shock system at outlet which forces the separated part of the boundary layer back on to the blade Surface. It is shown that a λ-shock series may form on a boundary layer which is apparently turbulent. This has not been observed before.