Numerical Study on Flow Separation Control of Adaptive Flap

Abstract

Improving the flow separation performance of blades is critical to the high efficient operation of turbomachinery as well as its safety. An adaptive flap similar to the bird feather was arranged on the blade suction surface. Numerical simulation method using SST k-ω turbulence model was performed to study the effects of flap lifting angles on the airfoil aerodynamic performance with different angles of attack. The flow characteristics and control mechanism were analyzed in terms of the macroscopic aerodynamic force and microscopic flow field. Results show that the varying separation field and the pressure distribution using the flap result in the variation of lift coefficients and drag coefficients, and then improve the flow separation performance of airfoil. The maximum lift coefficient of airfoil increases by 3.9% when the flap was in the condition with equilibrium aerodynamic moments. The maximum lift coefficient of the airfoil can be increased by 12.7% as the flap operated with optimum angles. When the flap operated with optimum angles, the moment coefficient of the flap approximately linear increases with the optimum angle at some extend. In practical application, this characteristics will provide references for the improvement of the flow separation control ability using external moments to constrain the flap motion.