Double S-shaped Inlet Design And Flow Control Investigation For All-wing Aircraft

Based on the demand of aircraft’s stealth performance and weight, the offset of the inlet was always designed large and the lengnth of the inlet was always short. But such kind of inlet has a heavy camber, it will cause strong secondary flow and leads to boundary layer separation, therefore,dramatically decrease the engine efficiency, compressor stability, and surge margins. Around this problem, a series of research has been carried out, including the following contents:(1)Studying the character of double S-shaped inlet model, complementing double S-shaped inlet’s parametrization design through radius transition method.(2)Analysing the mechanism and development of secondary flow, studying the influence of middle line changing rule,area changing rule and the ratio of the first and the second duct’s length for the inlet aerodynamics performance. Through numerical simulation analysis, these three factors influence the pressure distribution of the inlet wall, the best combination of these three factors is that the centerline changing rule choose the combination of modest turning amd modest turning, the area changing rule choose the combination of rapid turning at entrance and rapid turning at exit, the ratio of the first and the second duct’s length chooses 0.77.(3)Based on the traditional design method, in this paper, we always studied the shape of the interface of the first and second duct’s influence for the secondary flow. Through numerical simulation analysis, we found that the shape of the interface influence the sidewall’s camber, the larger the camber, the more stronger the secondary flow will be, Keeping the identical area, the best shape of the interface is rectangle with round edge.(4)Analyzing the influence of aircraft’s Mach number, attack angle, yaw angle and engine’s mass flow for the performance of double S-shaped inlet. The numerical simulation analysis result shows that the aircraft’s Mach number, attack angle, yaw angle mainly influence the quality of the incoming flow and engine’s mass flow affects the flow’s velocity in double S-shaped inlet.(5)Analyzing the mechanism of pusled jet, investigating the influence of jet frenquecy and jet flux. Through numerical simulation analysis, we found that the best jet frenquency is detach votex frenquency.