翼型近波浪水面气动特性研究

Aerodynamic characteristics of airfoil near wavy water surface

采用求解Navier-Stokes方程的数值方法研究了翼型NACA 4412近距离经过波浪水面时的气动特性。对数值方法的准确性进行了验证。计算了翼型经过波浪水面和固壁波浪地面2种边界条件下的气动力系数,并进行了对比。研究结果表明:翼型在经过波浪水面时气动力系数会发生周期性的变化,与固壁波浪的情况相比,气动力的变化曲线存在显著差异,波动幅度更大。通过对流场结构的分析,发现了翼型和波浪水面之间的作用机理。波浪水面的质点存在竖直方向上的运动,在小地面间隙时,水面质点向上运动会挤压翼型和水面之间的空气,从而造成翼型气动力大幅波动。同时解释了来流速度越大,气动力系数波动幅度减小的原因。

The aerodynamic characteristics of NACA 4412 airfoil moving over wavy water at small clearance is studied by solving Navier-Stokes equations.The accuracy of the numerical method is verified.The aerodynamic coefficients of airfoil moving over wavy water surface and wavy ground are calculated and compared.The results show that the aerodynamic coefficient changes periodically when the airfoil moves over the wavy water surface.Compared with the case of wavy ground,the variation curve of aerodynamic coefficient is significantly different and the fluctuation amplitude is larger.Through the analysis of the flow field structure,the interaction mechanism between the airfoil and the wavy water surface is found.The particles on the wavy water surface have vertical motion,when the clearance is small,the upward movement of the particles on the water surface will squeeze the air between the airfoil and the water surface,resulting in a large fluctuation of the airfoil aerodynamic force.At the same time,the reason why the fluctuation amplitude of aerodynamic coefficient decreases with the increase of incoming flow velocity is explained.