Effect of combined pressure and temperature distortion orientation on high-bypass-ratio turbofan engine stability

Total-temperature, static-pressure and total-pressure distributions were measured in the inlet duct upstream of the engine inlet and within the fan and compressor of a YTF34 turbofan engine. Free-stream and boundary layer yaw angle variations were measured between a rotable screen assembly and the engine inlet. Total pressure distortions were generated using three 180 deg extent screens and total temperature distortions were generated using a rotatable hydrogen burner. Reynolds number index upstream of the rotatable screen assembly was maintained at 0.5 (based on the undistorted sectors at station 1, the inlet flow measuring station). The engine mechanical fan speed at sea level condition was rated at 7005 rpm. The engine was tested at a corrected fan speed of 90 percent of rated condition. Yaw angle increased between the rotatable screen assembly and the engine inlet. The largest variation in free-stream and boundary layer yaw angle occurs when the combined distortions are 180 deg out-of-phase. Static-pressure distortion increased exponentially as flow approached the engine. Total-pressure distortions were attenuated between the engine inlet and the compressor exit. Total-temperature distortion persisted through the compressor for all four combined distortions investigated.