YLSG 107高升力翼型主动流动控制的数值模拟

数值模拟零质量射流与YLSG 107翼型绕流的干扰流场,探讨零质量射流在高升力翼型失速控制中的控制效果、控制特性及控制机理.数值模拟以积分形式雷诺平均Navier-Stokes(N-S)方程为控制方程,采用格心有限体积法进行求解.通过在喷口上施加非定常边界吹/吸边界条件模拟射流对翼型绕流的干扰.采用与风洞实验相同的来流状态和控制参数进行数值模拟,得到与实验相吻合的结果.为进一步研究控制特性和控制规律、提出改进的实验方案,研究不同动量系数、不同射流偏角对控制效果的影响,并对法向射流和近切向射流进行较深入的比较.研究表明,先前的风洞实验对应的射流动量系数(0.000 014)偏小是控制效果不显著的重要原因之一,必须达到0.001以上才有明显控制效果(射流动量系数为0.005时可使该翼型失速迎角增大2°,最大升力提高8.7%);近切向射流在失速控制方面明显优于法向射流.

Numerical Simulation of Active Stall Control on High-lift Airfoil

Interaction of synthetic jet and low-speed high-lift flow past a YISG 107 airfoil is simulated and stall control of high-lift airfoil is investigated. A cell-centered finite-volume scheme is used to discrete unsteady Reynolds-Averaged Navier-Stokes equations in integral form. An AUSM± up upwind scheme and a fully implicit dual-time step method are utilized for spatial discretization and time stepping, respectively. Implicit preconditioning method and geometric multigrid method are employed to remove stiffness encountered in simulation of low-speed flows and to accelerate convergence of computation. Influence of synthetic jet on main flow is modeled with a generalized unsteady blowing/suction boundary condition. Computational results with a synthetic jet located at 17.5% c from leading edge agree weU with low-speed wind tunnel experiment. With a momentum coefficient of 0.005, nondimensional frequency of 2.75 and jet angle of 20°, critical stall angle is delayed by 2°, and the maximum lift is increased by 8.7%. Influence of momentum coefficient and jet angle on stall performance is studied. It is shown that two key reasons lead to small improvement in previous wind tunnel experiments: One is due to low momentum coefficient. Only as momentum coefficient is larger than 0.001 can relatively evident improvement of stall characteristic be obtained. Another is due to unsuitable normal jet in tall control of a high-lift thick airfoil. Near tangent jet is better than normal jet.