Design Optimization of Complex Total Pressure Distortion Screens for Gas Turbine Engine Testing

Abstract In a gas turbine engine, inlet flow distortion occurs due to factor-s such as flow separation in the aircraft inlet due to aircraft manoeuvres and flight conditions. The distorted flow significantly impacts the performance of compressor and reduces efficiency of the gas turbine engine. In a compressor ground test facility, distortion screens are employed to simulate the distorted inlet flow experienced in flight conditions. In the present work, a methodology is developed to design complex total pressure distortion screens. Firstly, the total pressure loss characteristics of uniform porosity screens are evaluated by computations for screen porosities ranging from 0.20 to 0.90, and inlet Mach numbers ranging from 0.20 to 0.65. The influence of porosity on the total pressure loss for various inlet Mach numbers is highlighted in both incompressible and compressible flow regimes. Secondly, an inverse design methodology is formulated with the objective function to minimize the difference between the required and achieved total pressure patterns. Finally, this inverse design methodology is posed as an optimization problem, which is then iteratively solved using a gradient-based method until the required total pressure pattern is obtained. The proposed design optimization methodology is tested for several cases including actual gas turbine distortion patterns. The present work resulted in a robust design framework that can be utilized to design distortion screens based on the required total pressure distortion pattern for arbitrary inlet Mach numbers.