Experimental study of a serpentine inlet under ground running

Experiments of a serpentine inlet under ground running have been done and described in this paper.The study was performed in a low speed wind tunnel with an independent air-pumping system.It contains air-pumping tests at zero and different speeds of the free stream.The results show that:(1)When the inlet Mach number of the flow at exit increases,the total pressure recovery decreases,and the circular steady total pressure distortion coefficient,turbulence intensity and synthesis distortion increase.In comparison with the results measured in highspeed wind tunnel tests for the serpentine inlet at the same exit Mach number,the total pressure recovery is lower and the circular steady total pressure distortion coefficient,turbulence intensity and synthesis distortion are larger.(2)Under ground air-pump running,when the serpentine inlet is running at the exit Mach number Ma_e=0.45,the total pressure recovery coefficient equals 0.90,circular steady total pressure distortion coefficient equals 9.24%,turbulence intensity equals 4.6%,and synthesis distortion equals 13.85%,so it can be seen that the distortion of the flow delivered by the inlet may be too large to fit the engine.(3)When the air-pumping system and the wind tunnel are operating together,as it happens when the plane is ground taxiing,the performance of the inlet is getting better with the wind speed increasing.