航天器高温热保护系统传热计算与数值分析

【作者】 高宗战；

【导师】 岳珠峰；

【作者基本信息】 西北工业大学 ， 固体力学， 2006， 硕士

【摘要】 飞行器在高超速飞行时(Ma=8的速度)头锥、机翼和尾翼前缘等处的温度可高达1455°c-1793°c。为了保证飞机机体结构的完整、飞行人员的安全和机载设备的正常运转,在高超音速飞行器上需要敷设热保护系统。热保护系统对于飞行器的总体设计方案和性能具有举足轻重的地位。经过几十年来的发展,金属基热保护隔热系统逐渐脱颖而出,成为未来可重复使用航天运载器热保护系统的首选,因此,因此研究金属基热保护系统,对未来航天运载器的发展有着举足轻重的地位。本文内容就是对金属基热保护系统的传/隔热性能进行研究,主要针对多层隔热系统和蜂窝夹层隔热系统进行研究,主要工作如下: 首先,分析和研究了金属基多层隔热结构中的热传递过程,确定了其热传递的主要途径和方式。采用有限差分法和两通量方法来分析辐射和导热耦合作用下多层隔热结构在不同温度下的等效导热系数。另外,本文经过比较和分析发现:在金属基多层隔热结构中,对流传热对整个热传递影响有限。 其次,用有限单元方法模拟金属基蜂窝夹层隔热结构的热传导过程,分析影响其传热的主要因素; 再次,应用有限单元法模拟固—固接触时热传递过程,研究了接触体热传递的形式和特点。 最后,本文根据前面各项研究的方法和结论,研究了在恒定热流下飞行器前缘和头锥结构的隔热系统的热传递。 结果表明:对于多层隔热结构,由于辐射传热与温度成四次方关系,随着温度升高,等效导热系数也明显增大;对于蜂窝央层结构,等效导热系数是板上平均温度的函数,也随蜂窝高度与其外接圆半径之比有关。更多还原

【Abstract】 Aerodynamic heating generated in the shock layer surrounding can lead to the nose cap temperature as high as 1793℃, and the leading edges temperature can reach 1455℃, when space aircraft re-entry as speed as 8Ma in 27km high space. So it is necessary to establish insulation equipment, that can make inner temperature of aircraft decrease as low as 177℃, so as to make sure inner equipment and flight personnel sale. Several decade later, metallic thermal protection system’s develop have made great rapid progress, and will be considered lor insulating major portions of a new generation of reusable launch vehicles. Therefore, the insulation performance of space aircraft is investigated by. using theory analysis and numerical simulation.First, it is analyzed by theory that the progress of multi-layer insulation for space aircraft, gas natural convection contributions are minimal during the process, thus, il can be ignored. The combined radiation and conduction heat transfer through fibrous and multi-layer insulations is investigated using a finite volume approach and a two-flux formulation, the vary of effective thermal conductivity vs the vary of temperature will be gained. In the next place, heat transfer through honeycomb sandwich structure, high porosity structure, and contact heat transfer among solids is be molded using finite element method. Finally, heat transfer through the nose cap and leading edge of space aircraft is molded using finite clement method. This paper can provide some useful information for study of insulation of space aircraft.The following conclusions are reached based on the numerical simulation and theory analysis. The effective thermal conductivity of multi-lay insulation significantlyincreases with temperature increasing. The study ior honeycomb sandwich structure has shown that the most important structure parameter is as follows: honeycomb depth, honeycomb ribbon thickness, lace sheet thickness, in circle diameter of honeycomb, and temperature of upper and bottom sheet. For high porosity structure, it is high effective adiabatic structure.更多还原