【作者】 胡锐锋；

【导师】 武哲； 吴子牛；

【作者基本信息】 清华大学 ， 航空宇航科学与技术， 2012， 博士

【摘要】 高超音速飞行技术是21世纪航空航天技术发展的新制高点，目前高超音速技术已从概念和原理探索阶段进入到飞行器技术开发阶段。高超音速空气动力学技术是高速飞行器设计中的重要关键技术之一，气动力/热工程快速估算方法能够快速给出飞行器的气动力/热的大小，在高速飞行器初始概念设计和选型优化阶段有重要应用价值，建立能够对复杂三维高速飞行器气动力/热特性进行快速估算的软件平台十分必要。无控航天器再入大气层时在强烈的气动载荷作用下会发生解体并产生大量碎片，残存至地面的再入碎片可能会对地面产生很大威胁，提前预报再入碎片陨落时间和地点是减轻其灾害的重要措施。气动快速估算方法能够快速给出航天器和碎片所受的气动力和气动热，建立基于气动快速估算方法的碎片再入预测模型和软件平台是可行手段并具有重要应用价值。本文将介绍高速飞行器所在空间气动环境特性，并建立实用化的高超音速飞行器气动力/热快速估算软件平台和碎片再入预测与地面风险评估软件平台。首先分析高速飞行器的空间气动环境，在速度-高度图中给出流场无量纲参数分布规律和典型气动效应临界线，并对高速飞行器和再入碎片的综合气动环境进行分析。根据气动环境分析结果，论文中首次给出“软飞行”环境的概念。采用基于表面网格和表面流线的高超音速气动力/热快速估算方法开发气动力/热快速估算软件平台。连续流表面压力采用牛顿流模型等方法估算，气动热估算沿流线采用附面层近似解；自由分子流估算采用基于Maxwell平衡气体分布求解无碰撞Boltzmann方程得到的理论公式；过渡流估算采用桥函数方法。对几种典型高速飞行器气动特性进行估算，并与实验或CFD结果进行对比验证。结合验证计算结果，论文对影响气动估算精度的主要因素做了进一步讨论。基于气动估算方法建立简单外形物体的气动力/热工程估算模型，通过CFD方法和DSMC方法对部分气动模型进行校验。利用简单外形物体气动估算模型，建立碎片再入预测与地面风险评估软件平台，该平台可在几分钟内完成大量碎片再入仿真分析。与国外已有类似软件相比，本文建立的碎片再入与地面风险评估软件平台能够对更多种碎片外形进行仿真分析。更多还原

【Abstract】 The hypersonic flight is regarded as a new breakthrough of aeronautics andastronautics in21stcentury. In recent years the hypersonic technology has beenpromoted from conceptual and principal investigation phase to vehicle design anddevelopment phase. As one of the key techniques, engineering methods foraerodynamic prediction have been employed in many applications for conceptual andpreliminary design of hypersonic vehicles. Therefore it is necessary to establish asoftware platform which can predict the aerodynamics and aerodynamic heatings oncomplex three-dimensional vehicle very fast.The uncontrolled spacecraft like deorbited satellite or upper stage of spent rocketreenters the earth’s dense atmosphere at the end of their life. The strong aerodynamicand aerothermal loads can melt and break the structures into many pieces of debris,and the surviving ones can cause great risk to the ground. Debris reentry prediction isone way to mitigate the underlying hazard. It should be of great importance to build asoftware system to predict debris reentry based on engineering methods.This thesis focuses on the aerodynamic environment of hypersonic vehicles, theestablishments of hypersonic aerodynamic and aeroheating predition platform, theaerodynamic models for simple objects and debris reentry analysis and riskassessment system.Firstly, the aerodynamic environment of hypersonic vehicles is introduced,including the distributions of non-dimensional flow parameters and criticalaerodynamic lines in a velocity-altitude map. Then integrated analysis ofaerodynamic environment for cruising hypersonic vehicles and reentry debris will begiven. A new concept of ‘soft flight’ is proposed for the first time based onaerodynamic environment analysis.We establish the hypersonic aerodynamic and aeroheating predition softwareplatform via methods based on surface grids and streamlines. For continuum flow, thesurface pressure is calculated by methods of Newtonian flow model and others, and the aerodynamic heating is computed along surface streamlines using approximateboundary layer solutions. For free molecular flow, theoretical formulae by solvingcollisionless Boltzmann equation using the Maxwell equilibrium gas distribution areadopted. For transitional flow, we use bridging relations. The aerodynamic propertiesare calculated and validated for several typical configurations, comparing withexperimental data or CFD results. According to the validation work, we performfurther discussions and conclusions on some vital factors which may influenceprediction accuracy.The aerodynamic models for simple objects are proposed. The models arevalidated by CFD or DSMC computations. Based on the aerodynamic models ofsimple objects, we build the software system for debris reentry and risk assessment.The system can predict the reentry of hundreds of distinct debris at the same time inseveral minutes. Compared with other similar tools like DAS and ORSAT, presentsoftware system provides models for more object shapes.更多还原