Stall Margin Improvement and Increase Pressure Ratio in Transonic Axial Compressor Using Circumferential Groove Casing Treatment

Abstract

Maximum pressure ratio and aerodynamic blades loading are the most important factors in designing axial compressor restricted by minimum airflow. The present work aims to stall margin and total pressure ratio in transonic axial compressor using circumferential groove casing treatment (CGCT). In the first step, untreated compressor was simulated, compared, and agreed well with the experimental data. Then the treated rotor was simulated and results indicated that using CGCT improves the stall margin and increases the rotor pressure ratio. Stall margin was improved by 8% and the pressure ratio before stall condition and at the design point increased by 2.6% and 2.8 %, respectively. Additionally, it replaces normal shock with oblique shock near instability, causing less total pressure drop, moreover, the oblique shocks occurrence restricts separation zones and assists the rotor to perform far from instability. Furthermore, axial speed passing through rotor in a certain mass flow increases by 15 m/s, and then kinetic energy and stability increased. However, total efficiency of rotor reduces near 1%. In the last step, engine was analyzed with the aid of cycle analysis and leads to 62kW increase in shaft power as well as 1.87 g/kNs less fuel consumption due to 2.8% increase in the rotor pressure ratio.