IGTC-25 Numerical and Experimental Study on Deep Stall Cell Behavior in an Axial Compressor(Session A-8 ROTATING STALL IN AXIAL COMPRESSORS)

概要

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Numerical and experimental studies are conducted to reveal flow structure of fully developed stall cells in a single-stage axial compressor. To simulate unsteady flows in linear rotor-stator cascades, two dimensional compressible Navier-Stokes equations are solved numerically by applying a TVD finite-difference scheme. Furthermore, flow vectors ahead of and behind the stalled cascades in a test compressor are measured by a split-type hot-film probe. In the simulation, a huge forced vortex ahead of the rotor and a counter-circulating flow inside the stator are found to develop to form an axially-aligned deep stall cell, which propagate in the direction of the rotor motion with a speed of 60% of the rotor speed. This is close to the measured speed of 53-55% in the test rig. From the hot-film measurements, flow ahead of the rotor was found to have strong circulation in the stall cell, as similarly found in the simulated flow. While the stalled regions are concentrated near the tip ahead of the rotor, they are found to be distributed evenly behind the stator, with slightly larger flow fluctuation near the hub. Not only tip leakage flow and flow separation at the stator hub, but also passage contraction may be responsible for the three dimensional feature of the cell structure in the test rig.
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