Numerical Investigation of Rotating-Stall in a Stage of an Axial Compressor with Two Different Approaches

An unsteady two-dimensional finite-volume solver was developed based on Van Leer’s flux splitting algorithm in conjunction with “Monotonic Upstream Scheme for Conservation Laws (MUSCL)” limiters and the two-layer Baldwin-Lomax turbulence model was also implemented. To validate the solver, two test cases were prepared and the computed results had good agreements with reference data. The rotating-stall-like (RS) effect in a multi-blade 2-D stage of an axial compressor was investigated. The RS was captured with a 40% reduction in flow coefficient and a 0.4% increase in load coefficient with respect to normal operating condition. The velocity traces showed a periodic behavior during RS. The same behavior was observed with a stator-free approach, but with different modal characteristics. Finally, the RS vortices and its flow characteristics were observed in detail, and the stator-free approach seemed to be more adequate in stability margin determinations. The same observation is finally prepared for variable number of blades to show the dependency of the RS modal characteristics to number of blades, and to find the minimum required number of blades in numerical analysis of RS.