Research On Two-dimensional Forebody Boundary Layer Transition

The boundary layer transition of the fore-body of the 2-D inlet was researched in this paper with Wind tunnel experiments and numerical simulation. According to the investigation results, an aerodynamic control method of boundary layer transition was presented, and the CFD were conducted.Firstly,the transition experiment was conducted in the air-breathing wind tunnel of Ma3.0,and the CFD study were carried out based on the experimental result. The results indicated: the RMSEs gained by statistics processing of the dynamic pressure measured by the dynamic pressure sensors,had the magnitude changes, and the transition position was basically identified through the measure based on experimental condition. Judged by the RMSE curve of different oblique angle, the transition onset was delayed as the angle of attack was increased. Under the wind tunnel condition,3-D CFD research on the 5°inclined plate was made, and the result showed that the transition positions were agreed with experimental results well.Secondly,studies were made to discover the influence factors of the 2-D fore-body transition,such as: geometry parameters and flow parameters, etc. The results showed that the greater the flow turbulence was, the more obvious the transition position was advanced. The shock wave before the transition was so big that the transition behind the shock was nearer to the shock. The shock wave position moved forward, causing the forward moving of the transition onset, but the gap between them increased. When the leading radius was increasing, the transition position firstly remained unchanged within a certain area, then dramatically delayed. The 3-D CFD results showed that the delay of transition position was more evident than the 2-D results, and the transition position of the section closed to the edge was more delayed than that of the symmetry.Finally, a control technique of 2-D fore-body boundary layer transition based on pressure was proposed,and numerical simulations was studied. The results showed that,for the straight channel,the transition position moved advance with the channel width and flow capacity increased. The channel exit width had an influence on the transition through the exit flow, and the channel entrance width through the channel loss. The transition position moved forward in a certain range with the channel exit position near the leading edge, and when the exit was in a certain location,the transition delayed more than nature transition because of the increasing channel loss and exit disturbance reduction. The variation of transition when the fluid-introducing channel existed, was consist with thatwhen the fluid-introducing channel didn’t exist, and when the fluid-introducing channel existed amplitude of variation was smaller.