The Influence of Periodically Incoming Wakes on the Separating Flow in a Compressor Cascade

Two Direct Numerical Simulations (DNS) of flow in the V103 Low-Pressure (LP) compressor cascade with incoming wakes have been performed employing different intensities for the incoming wakes. The computational geometry was chosen in accordance with the setup of the experiments performed by Hilgenfeld and Pfitzner at the University of the Armed Forces in Munich. The computations were carried out on the NEC SX-8 using 64 processors and 85 million grid points. The incoming wakes stem from a separate DNS of flow around a circular cylinder. While in the simulation with the weaker wakes the flow along the suction side was found to remain separated for all phases, in the simulation with the stronger wakes separation was periodically completely suppressed. As the boundary layer separated, it was found to roll up due to a Kelvin-Helmholtz instability triggered by the periodically passing wakes. Inside the rolls further transition to turbulence was observed.

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