基于N-S方程的飞机风挡雨刷气动力计算

Computational research on aerodynamic forces of aircraft windshield wiper based on the N-S equations

风挡雨刷在飞行过程中易出现被气流吹离复位位置、飘起现象,阻碍飞行员视野,严重影响飞行安全。选取某型机风挡雨刷作为优化对象,采用了结构、非结构混合网格的办法,在机身壁面附近生成结构化网格,在雨刷机构表面生成非结构化网格,用Interface面将两部分结合生成雨刷最终计算模型。利用Fluent软件,基于N-S方程和S-A湍流模型,采用时间平均法对不可压缩流的参数进行时均化,计算了不同飞行状态下,风挡雨刷在复位位置以不同角度停放及增加扰流板时所受气动力,对风挡雨刷的外形及停放角度进行优化,比较分析了优化前后雨刷所受气动力。仿真计算结果表明,雨刷合理的停放角度、在刷臂上加装扰流板能有效引导风挡雨刷迎风面气流的方向,从而减小雨刷迎风面所受气动力。通过试飞验证了数值计算的可靠性及优化方案的可行性,为风挡雨刷预紧力的设置及复位位置的确定提供依据。

A short paper has been presented to show the phenomenon that the aircraft windshield wiper is blown away from the parking position during the flight.This behaviour has effect on the vision of pilots and copilots,and significantly impacts the flight safety.A windshield wiper was taken as the present study object.Hybrid structured-unstructured grids were adopted for the simulation.Structured grids were used around the fuselage,and unstructured grids were on the wiper framework.An interface was used to combine these two parts,and to generate the final calculation grid.Fluent code was employed to simulate fluid dynamics over windshield wiper.Numerical simulations were carried out based on N-S equations and S-A turbulence model.The incompressible flow parameter was handled by time-averaged method.The aerodynamic forces of the windshield wiper were calculated for several flight states at parking position with different angles and shapes.According to the comparison and analysis,the simulation results indicate that the airflow on the windward surface can be effectively guided by a reasonable parking angle and the spoiler on the wiper arm.This phenomenon consequently decreases the aerodynamic forces.The optimized proposal has been validated by flight test,provided theoretical support for the pretightening force and parking position.