弹射救生高速气流吹袭防护气动特性数值模拟

对弹射救生中高速气流吹袭防护装置对人椅系统气动特性影响进行了数值模拟.采用基于面的有限体积方法求解N-S方程,空间离散采用中心格式,时间离散采用五步显式Runge-Kutta方法.基于Spalart-Allmaras(S-A)紊流模型的DES方法,数值模拟了人椅系统在马赫数0.6、迎角-90°～90°的气动特性,获得了与风洞试验结果较为吻合的计算结果.对有无导流挡板和抬腿机构人椅系统的气动特性及飞行员胸腹部表面压力分布进行比较,结果显示两种防护装置均可有效改善人椅系统的气动特性,不同程度降低飞行员胸腹部所承受的气动力,充分说明高速气流防护装置的有效性.为进一步研究高速气流防护装置提供参考.

Numerical Simulation for Windblast Protection During High Speed Ejection

The effects of windblast protective devices on the aerodynamic characteristics of crewman/ejection seat during high speed ejection are numerically simulated. Reynolds-averaged Navier-Stokes equations are solved by the unstructured finite volume method. Central difference scheme is used for spatial discretisation and five-stage Runge-Kutta scheme is applied for temporal discretisation. The DES method based on S-A one equation turbulence model is adopted to simulate the aerodynamic characteristics of crewman/ejection seat at Mach number 0.6,the angles of attack from -90 to 90° . The results coincide well with the wind tunnel experiments. The aerodynamic characteristics of crewman/ejection seat and the pressure distribution on the crewman chest and abdomen with or without wind deflector and leg lifters were evaluated. It is shown that these windblast protective devices efficiently improve the aerodynamic characteristics, and decrease the aerodynamic forces loaded on the crewman chest and abdomen more or less.