Prediction and test verification of inlet distortion based on flight test data

Experimental design of response surface methodology was adopted to construct the inlet pressure distortion prediction model based on flight test data, while the inlet distortion model prediction and flight test verification were studied under different flight conditions. The results showed that, compared with the flight test results, the model prediction average relative error of the comprehensive pressure distortion index was 421%, and the average relative error of the steady-state circumferential distortion index was 799%, which were in agreement with each other and can meet the requirement of the inlet distortion prediction. At large angle of attack, sideslip and combined flight conditions, the flow separation of the boundary layer inside the inlet contributed a lot to the distortion of the inlet outlet. The position of the inlet outlet low pressure zone corresponded to the flight attitude angle, and there was a small range of deflection in the direction of the compressor rotation in the circumference direction, and the deflection angle was related to the engine state. The model of “model prediction+flight test” can be used to evaluate the distortion characteristics of aircraft inlet completely, safety and efficiently, and it has good engineering practicability.