大型航天器再入解体气动力热特性模拟的直接模拟蒙特卡洛方法研究  

DSMC Approach for Simulating Aerodynamic Thermal Characteristics During Large-scale Spacecraft Reentry

作　　者：梁杰[1] 李志辉[1,2] 李绪国[1] 杜波强[1] LIANG Jie;LI Zhihui;LI Xuguo;DU Boqiang(Hypervelocity Aerodynamics Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China;National Laboratory for Computational Fluid Dynamics,Beihang University,Beijing 100191,China)

机构地区：[1]中国空气动力研究与发展中心超高速空气动力研究所,绵阳621000 [2]北京航空航天大学北京前沿创新中心国家计算流力学实验室,北京100191

出　　处：《载人航天》2020年第5期537-542,549,共7页Manned Spaceflight

基　　金：国家重点基础研究发展计划(2014CB744100);国家自然科学基金(91530319、11325212)。

摘　　要：为模拟大型航天器离轨再入近连续过渡流区高超声速气动力/热绕流特征,构建了基于直接模拟蒙特卡洛法碰撞限制器技术的混合方法,发展了基于密度梯度的动态自适应混合网格处理技术与变时间步长计算方案。利用当地流动梯度的克努森数作为判断连续流失效的参数,将流场划分为不同区域,在连续流区采用碰撞限制器以及大网格尺度和大时间步长,在流场的大梯度区域——包括激波和壁面边界层区域——采用基于当地密度梯度的动态自适应碰撞网格和取样网格处理技术。为保证整个流场范围每个碰撞网格内的模拟粒子数分布更加均匀,采用变时间步长计算方案,并固定当地时间步长与粒子权重的比值,避免了因分子穿越网格界面产生的复制或消失。通过计算类天宫飞行器低密度风洞试验状态的气动力系数,并与试验数据对比,验证了上述算法的高精度模拟能力与可靠性。同时模拟分析了带太阳电池帆板的类天宫飞行器再入85 km高超声速复杂气动力热,及头部对接台与板舱非规则物形绕流所致激波/边界层干扰、流动分离与强气动力热致太阳电池帆板毁坏发生首次解体机制。To simulate the aerodynamic thermal characteristics during large-scale spacecraft reentry,the implementation of a collision limiter DSMC-based hybrid approach was presented to simulate hypersonic near-continuum transitional flow for complex disintegration of Tiangong-type spacecraft on expiration of service.The continuum breakdown parameters based on the gradient-length local Knudsen number were characterized with different regions of the flow field.The collision limiter was used in the continuum flow regions with large time step and cell size.The local density gradient-based dynamic adaptation of collision and sampling cells refinement was employed in high gradient regions including strong shocks and boundary layer near surface.A variable time step scheme was adopted to make sure a more uniform distribution of simulated particles per collision cell throughout the computational domain,with a constant ratio of local time step interval to particle weights to avoid particles cloned or destroyed when crossing interface from cell to cell.The aerodynamic coefficients of Tiangong-type vehicle in low-density wind tunnel test conditions were computed and compared with experimental data to validate the reliability of the present method.The complex shock wave interaction and flow separation around Tiangong-type vehicle with solar panels were simulated and analyzed for hypersonic near-continuum transitional flow.

关 键 词：大型航天器 再入解体 气动力热特性 直接模拟蒙特卡洛方法 碰撞限制器技术 激波/边界层干扰 

分 类 号：V211.3[航空宇航科学与技术—航空宇航推进理论与工程]