降雨条件下翼型的气动特性

采用计算流体力学方法对降雨条件下翼型的气动特性进行了研究.通过求解定常可压的Navier-Stokes方程来计算流场,采用拉格朗日法对流场中的雨滴轨迹进行了模拟跟踪,得到了翼型表面的雨滴收集率;建立了水膜层数学模型,并假定水膜层沿着翼型表面的法向方向增长,预测了降雨引起的翼型外形的变化,并得到了水膜层表面的粗糙度高度;采用k-ωSST(shear-stress transport)两方程湍流模型结合增强的壁面函数,研究了降雨对翼型气动特性的影响.结果表明,在低迎角范围内,降雨对翼型的升力系数和阻力系数影响很小;当达到失速迎角后,降雨会引起上翼面边界层气流的提前分离,造成翼型气动性能的严重损失. 

Study of aerodynamic characteristics of an airfoil in rain

The aerodynamic characteristics of an airfoil in rain were studied using computational fluid dynamics method.The flow field was calculated by solving the steady compressible Navier-Stokes equations.The trajectories of raindrops in the flow field were tracked with Lagrange method and the collection efficiency of airfoil surfaces was obtained.The model of water film was also set up,then assuming that water film accumulates layer-by-layer in the direction normal to the airfoil surface and the changes of airfoil shape due to rain and the roughness height on water film were predicted.The influence of rain on aerodynamic characteristics of the airfoil was studied using k-ω SST(shear-stress transport) two equations turbulence model with enhanced wall treatment.The results show that rain effect on the lift coefficient and drag coefficient of the airfoil is little within the low angles of attack;rain can cause boundary airflow separation on upper surface and thus result in serious aerodynamic penalties when the airfoil is nearly stalled.