Assessment of the Self-Recirculating Casing Treatment Concept to Axial Compressors

Performance characteristics of a transonic axial flow compressor called NASA Rotor 67 have been analyzed using a three-dimensional time accurate Navier-Stokes analysis. The operating range is limited at low-mass flow rates due to the occurrence of 3-D stall which grows with time causing surge. This study investigates the use of a passive technique called ‘Self-Recirculating Casing Treatment ’ that has been proposed at the U.S. Army Research Lab to alleviate the stall phenomenon and restore stable operation for previously unstable conditions. It is demonstrated that the stable operating range can be extended by delaying the initiation of surge. Nomenclature P0 = total pressure T0 = total temperature PP = plenum pressure VP = plenum volume cm = exit mass flow rate tm = plenum throttle mass flow rate K = plenum chamber constant κ = recirculation loss factor aP = speed of sound in the plenum chamber γ = Ratio of specific heats I