In this paper, we have investigated numerically the interaction between secondary flow and a normal compression shock in a transonic turbine cascade. We observe that the sudden deceleration caused by the compression shock triggers an instability in weaker regions of the vortex system. This instability forms a pattern of concentric rings of elevated vorticity, which, in turn, cause the shock to deform into the same concentric wave-like pattern. The same pattern appears in the entropy distribution just downstream of the shock as a result of the uneven shock-intensity distribution.

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Compressor cooling is a promising method for increasing the efficiency of aero engines. This paper shows that the application of this method is not limited to the thermodynamic effect of extracting the net heat flow, but also extends to the heatflux distribution provided by the cooling. To demonstrate this, we conducted an extensive numerical study featuring a wide range of heating and cooling distributions applied to the casing of a compressor rotor in a singlestage model, which was taken from the last stage of an experimentally validated fourstage highspeed compressor model. The results show that the benefit – or detriment – of these variations may be significantly impacted by the heatflux distribution applied. We show that, while the net heat flux proves to be the dominant factor, the local distribution may account for up to 14% in the massflow variability and up to 21% of the variation in the adiabatic rotor efficiency. The results suggest an influence of the heatflux distribution on the tipleakage vortex.

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