An efficient flow control technique based on co-flow jet and multi-stage slot circulation control applied to a supercritical airfoil

Circulation control is a kind of efficient flow control technology which can improve aircraft aerodynamic performance and reduce fuel consumption. However, improving the aerodynamic efficiency of a circulation device to enhance flight endurance and achieve environmentally flying is a challenging problem for the application of circulation control. This paper presents an efficient flow control technique that combines co-flow jet and multi-stage slot circulation control. The combinational flow control technique is applied to a supersonic airfoil to test its energy consumption and aerodynamic benefit achievement. Results show that both the single and double slot circulation control can improve the maximum lift-drag ratio of the baseline airfoil, with an increment of 11.3% and 19.1%, respectively. Compared with the single application of co-flow jet control which can increase the lift-drag ratio of the baseline airfoil by 16.3% and extend the stall angle of attack from 6° to 8°, the combinational flow control can obtain a more significant lift-drag ratio increment by about 27.3% and eliminate flow separations at high angle of attack. The stall angle of attack can even be increased to about 10°. Additionally, the blowing efficiency of the circulation control airfoil has been comprehensively analyzed. The results show that the maximum effective lift-drag ratio and highest blowing efficiency can be achieved at a blowing coefficient of 0.00235.