Numerical Analysis of Tip Leakage Flow Field in a Transonic Axial Compressor Rotor

概要

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Tip leakage flow field in a transonic axial compressor rotor, NASA Rotor 37, were investigated by large-scale numerical simulations. Unsteady three-dimensional flow simulations were conducted by solving the compressible RANS (Reynolds-averaged Navier-Stokes) equations with k-ω turbulence model using an implicit high-resolution upwind scheme based on a TVD formulation. Vortical flow structures were focused on in order to investigate the tip leakage flow field in detail. At the tip leakage flow field in the rotor passage, the tip leakage vortex interacts with the shock wave formed upstream of the leading edge of rotor blade. This interaction has a great influence on the loss at the tip flow region. In addition, the simulation shows that the vortex breakdown occurs in the tip leakage vortex at near-stall condition due to this interaction, generating a large blockage effect near the tip in the rotor passage enough to trigger the stall of compressor. The breakdown leads to the unsteadiness in the tip leakage vortex, which causes the periodical fluctuations of blade torque, playing a major role in the unsteady phenomena in the tip leakage flow field.
2006-03-20