In axial flow compressors, tip vortices arise from the difference in presure between the suction and the pressure side and roll up over the suction side of a rotor blade. The trajectory of the vortex begins at the tip of the leading edge with a feeding sheet along the edge of the tip and propagates into the passage. In the case of a transonic turbocompressor, the vortex must cross the passage shock caused by flow deflection on the pressure side of the neighboring blade. The shock-vortex interaction leads to a sudden and strong deceleration of the flow, and hence to a strong change in the vorticity distribution within the vortex. Depending on the intensity of the shockvortex interaction, there may be vortex breakdown. This paper gives detailed analyses on tip vortex development and topology as well as shock-vortex interaction. Numerical flow simulations were done for the NASA Rotor 37. The results confirm that vortex breakdown is associated with compressor surge, and may in fact even cause it.
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