The Effect of a Variable Cantilevered Stator on 1.5-Stage Transonic Compressor Performance

Future aero engine designs must address environmental challenges and meet noise and emissions regulations. To increase efficiency and reduce size, axial compressors require higher pressure ratios and a more compact design, leading to necessary modifications in the variable stator vanes, especially in the stator hub region. This study examines the impact of a variable cantilevered stator on the performance and aerodynamics of a 1.5-stage transonic compressor, representative of a high-pressure compressor front stage. Experimental tests at the transonic compressor test rig at Technical University of Darmstadt involved two variable stators with identical airfoil designs but different hub configurations, using the same inlet guide vane and rotor. Detailed aerodynamic analysis was conducted using steady and unsteady instrumentation. The cantilevered stator achieved a 2% increase in efficiency and a 1% increase in total pressure ratio, due to higher aerodynamic loading and reduced pressure losses. The primary performance gain comes from the reduction of the hub blockage area. The cantilevered stator also performed well at near stall conditions, unlike the shrouded stator. Time-resolved measurements indicated that loss mechanisms are closely linked to the rotor wake phase. Overall, variable cantilevered stators outperformed shrouded stators in this compressor stage.