NUMERICAL STUDY ON THE AERODYNAMIC PERFORMANCE OF THE WAVY LEADING- EDGE BLADE UNDER ZERO-NET-MASS-FLUX JET

Aiming at the problem of stalling and flutter buffeting caused by the flow separation of vertical axis fan blades under the condition of high attack angle, zero-net-mass-flux jet excitation is introduced to control the flow separation of wavy leading edge blades. The numerical model of the flow around the static wavy leading-edge blade was established by the large eddy simulation method, the lift and drag characteristics and the flow separation mechanism of the wavy leading-edge blade was analyzed after adding the zero-net-mass-flux jet, and the influence of the change of jet parameters (jet position and momentum coefficient) on the stall characteristics of the wavy leading-edge blade was explored. It is found that the wavy leading-edge under the controlled and uncontrolled condition at large attack can induce the generation of small-scale streamwise vortex, and reduce the size of the rear large separation vortex, so that the coupling effect between the wavy leading-edge and the jet is better than that under the control of the jet or wavy leading-edge. Blowing of the zero-net-mass-flux jet makes the leading-edge flow-to-vortex have higher kinetic energy resistance to inverse pressure gradient, thus delaying flow separation. Inhaling will suck away the low momentum fluid of streamwise vortex, thus inhibiting the development of streamwise vortex into large separation vortex. The jet is located at a distance of 0.033c from the baseline leading edge, which is at the forefront of the leading edge streamwise vortex, allowing it to participate most effectively in the generation of the leading edge streamwise vortex, resulting in the best improvement in lift-to-drag ratio. Moreover, the increase in lift-to-drag ratio enhancement is proportional to the increase in momentum coefficient. However, the control economy is optimal when the momentum coefficient is 0.018. It provides useful support for the stall control of vertical axis wind turbines.