Improving the Lift Characteristics of Supersonic Double 257 Wedge Airfoil at Low Speed Using Passive-Active Flow Controlling Methods


The supersonic double wedge airfoil performs quite excellent in the supersonic speed regime but would lead to poor performance at subsonic speed regime due to sharp edges stall. For this purpose a theoretical and experimental study was undertaken to improve performance characteristics of the supersonic double wedge airfoil at low speed by using passive-active flow controlling methods. The proposed passive method was a shape modification through changing the sharp leading edge and mid- section upper and lower surface apex to smooth curved control segment actived during subsonic flight regime; and the blowing technique was used as an active method. ANSYS FLUENT CFD package was used to simulate the flow around the standard and modified airfoils. Low speed wind tunnel tests were also conducted in order to measure pressures and velocities chordal-wise the model airfoils fabricated to accomplish these wind tunnel tests. The results had proven that the proposed flow controlling methods had improved the performance of the double wedge airfoil at low speed. The maximum lift coefficient C_(l,max) was increased by about (38%) and the stall angle for C_(l,max) was jumped from (12°) for the standard airfoil to (18°) for the modified airfoil with blowing. The experimental results coincide well with the theoretical results.