Boundary layer blowing characteristics of bump inlet by wind-tunnel test

Based on the low and high speed wind tunnel，a test system for measuring the boundary layer blowing characteristics of the bump inlet at a wind tunnel was designed and set up. The boundary layer blowing characteristics were studied by test at different incoming Mach numbers and flow ratios. Through analysis of the test data, calculation and comparison of the flight test results of the same type, the boundary layer blowing characteristics of the bump inlet were studied. Results showed that the boundary layer blowing ability of the bump inlet gradually decreased with the increase of the flow ratio at the same incoming Mach number.Within the wide range of the flow ratio at subsonic, the pressure coefficient of the bump inlet surface was symmetric along the center line with high pressure gradient, and it increased along the mainstream. The bulge structure showed a relatively strong blowing ability of the boundary layer. The flow ratio range with effective blowing ability at supersonic was significantly smaller than that at subsonic. At supersonic the bow-shaped shock wave of the inlet lip was the main factor affecting the pressure gradient change at different positions on the bump surface and the boundary layer blowing ability. Under the flight conditions near Mach number 18 and above, the boundary layer blowing ability was decreased, and the separation of the boundary layer flowing was strengthened, causing large loss and distortion of the inlet pressure.