低雷诺数下双元素翼帆翼型失速特性的数值研究

Numerical Simulation of Stall Characteristics of Two-Elements Wingsail Airfoil at Low Reynolds Number

为了研究大型船舶在航行中双元素翼帆的失速特性,采用Transition SST湍流模型求解双元素翼帆翼型流场,进而分析双元素翼帆失速特性的变化规律。通过在襟翼偏转角增大时双元素翼帆的流动变化分析翼型表面流动分离的演化过程:随着襟翼偏转角的增大,助推力系数出现波动式增大,这是由于在多物理参数共同作用时,其中某一参数的变化会带来缝隙绕流的扰动,改变两个自由剪切层的相互作用,造成翼型失速或者改善流动。对于不同襟翼偏转角,在相对风向角为75°~105°内的助推力系数最大,侧推力系数也接近0值,属于最优相对风向角范围。因此双元素翼帆在工作中,当相对风向角改变而引起攻角变化时,为了获得最优推进系数,应先选择襟翼偏转角,再选择合适的攻角。

In order to study the stall characteristics of two-elements wingsail of merchant ships during navigation,the transition SST turbulence model is used to solve the airfoil flow field of two-elements wingsail,and the stall characteristics of two-elements wingsail are analyzed by numerical simulation.The evolution process of flow separation on the airfoil surface can be seen from the flow change of the two-elements wingsail airfoil when the flap deflection angle increases.With the increase of flap deflection angle,the thrust coefficient fluctuates and increases.This is because when multiple physical parameters act together,the change of one of them will bring disturbance to the flow around the gap.The interaction between two free shear layers also has been changed,causing airfoil stall or improving flow.For different flap deflection angles,the thrust coefficient is the largest in the range of 75°~105°relative wind angle,and the side thrust coefficient is close to 0.It belongs to the range of optimal relative wind angle.Therefore,when the angle of attack changes due to the change of relative wind direction,in order to obtain the optimal propulsion coefficient,the flap deflection angle should be selected first,and then the appropriate angle of attack should be selected.