【作者】 刘双；

【导师】 张博明；

【作者基本信息】 哈尔滨工业大学 ， 工程力学， 2010， 博士

【摘要】 高超声速飞行器是现代飞行器发展的主要趋势。然而,高超声速飞行器要实现跨大气层以及在大气层内长时间、超高速、机动飞行,将遭遇特殊和严酷的热环境,这对防热结构灾气动和耐高温性能方面提出了严苛的要求。选择适合高超声速飞行器不同部位的热防护系统,并测试其各自的防-隔热能力和冷却能力成为亟待解决的问题。其中,主动冷却热防护系统以其冷却能力强、可以抵抗高热流密度的长时间加热、实现温度和热流的开环或者闭环控制、实现防热、隔热和热控制的一体化设计,具有可重复使用性等特点成为解决高超声速飞行器防热问题的有效方法,是研究的热点和关键技术。本文以高超声速飞行器的防热结构为研究对象,基于在高热流密度下长时间飞行的要求,对适应于高超声速飞行器的主动冷却金属热防护系统进行了多方面的研究,主要研究内容包括以下几个方面：基于高超声速飞行器热防护的特征及需求,提出采用冷却流密度和冷却模式相结合作为表征和评估主动冷却热防护系统参数的方法,在此基础上采用有限差分法建立了被动-主动热防护一体化分析评价模型,并采用这一模型对高超声速飞行器的被动冷却热防护系统和主动冷却热防护系统的冷却特性和冷却效能进行了定量的分析比较；结果表明,对于被动冷却热防护系统,增加隔热层材料的厚度可以降低内部结构的温度,但是随着隔热层厚度的增加,隔热层对内部结构温度的影响减少,增加隔热层厚度对于短时间加热的热防护系统有效,而对长时间加热的热防护系统防热效率很低。要满足高超声速飞行器的工况要求,隔热层材料的厚度至少增加2-3倍。对于长时间加热热防护系统,主动冷却具有很高的冷却效率和防热效率,可以满足内部结构温度的要求。该方法和模型在论文第四章的发汗冷却金属热防护系统的设计和冷却能力评估中得到应用,验证了其有效性和工程实践价值。针对主动冷却热防护系统的多孔隔热材料,基于热传导,热辐射和多孔隔热材料内部微观结构,采用光学厚近似法,建立了高温隔热毡和金属泡沫材料的有效热导率的理论模型,对高温隔热毡和金属泡沫的有效热导率进行了实验测量,其结果与理论计算结果吻合,验证了模型的有效性和适用性,为主动冷却热防护系统的设计提供基础和前提。针对高超声速飞行器大面积防热区域的高热流密度部位,基于采用冷却流密度作为表征和评估主动冷却热防护系统参数的思想,采用防热-热控制一体化的设计方法,设计并制造了发汗冷却金属热防护系统,搭建了采用底部辐射加热的高温辐射加热平台,加热温度可以高达1500K,并持续加热2小时,实验测试了发汗冷却热防护系统的冷却效能。根据发汗冷却自身的冷却特点和第二章的被动-主动热防护一体化分析评价模型,分析计算了发汗冷却金属热防护系统的冷却能力,实验结果验证了该模型的有效性。结果表明,发汗冷却热防护系统整体结构热载荷排散能力至少提高70%,冷却功率为170-500kW/m2(耐高温合金),内部结构温度低于水的沸点温度(发汗冷却作用情况下)。针对高超声速飞行器头锥、翼前缘部位,提出将喷雾冷却应用于金属热防护系统的新方法,基于采用冷却流密度作为表征和评估主动冷却热防护系统参数的思想,采用防热-热控制一体化的设计方法,设计并制造了一种新型采用喷雾冷却的金属热防护样件,搭建了氧乙炔实验平台,实验测试了喷雾冷却金属热防护系统样件的冷却效能。更多还原

【Abstract】 Hypersonic vehicle is the developmental direction of modern vehicles. The extreme severe aerodynamic heating and special surrounding encountered by hypersonic vehicle due to the long time mission between and in aerosphere with high speed, which makes traditional thermal protection system exposed to more possible failure modes on dynamic and high temperature performance. The knowledge of active cooling thermal protection system with suitable active cooling capacity is crucial to solve the question for thermal protection of hypersonic vehicle. Active cooling thermal protection system with high cooling capacity, resistance of high heat flux in long time, realization the open loop or close loop control on temperature and heat flux, integration design of thermal protection-insulation and thermal management, which makes active cooling TPS to be a hot spot of research and key technology in research of hypersonic vehicle. In present paper, thermal protection of hypersonic vehicle subjected to severe aerodynamic heating in long time is investigated. The active cooling metallic thermal protection systems which have potential to apply to hypersonic vehicle is studied on. The main research contents of the papers are as follows:An integrated thermal protection-thermal insulation-thermal management design method and numerical model was developed base on the character and requirement of thermal protection system on hypersonic vehicle in order to quantitatively compare the cooling characteristic and cooling capacity of passive and active cooling thermal protection systems. The results indicate that the temperature of inner structure decreased when the insulation thickness increased, but the effect on the temperature decrease when the insulation thickness increased, meanwhile, this method is effective for thermal protection system which encountered short time heating load, not for long time heating load. The thickness of insulation would increase at least 2-3 double if the method of increasing the insulation thickness was employed. Active cooling has high cooling capacity and cooling efficiency for thermal protection system which encountered long time heating load and keep the temperature of inner structure within the operational temperature limit. The method and model are applied on the design and evaluation the cooling capacity of the transpiration thermal protection systems. The validity and engineering practice value are proofed.A theoretical model was developed to predict the effective thermal conductivities of the porous material base on the conduction and radiation as well as microstructure inside the porous material. The experiment on the effective thermal conductivities was conducted. The experimental results according to the predicted results indicate the model is availability and applicability, which is the basement for the design of active cooling thermal protection systems.Transpiration cooling thermal protection system was design and developed using the method of integrated thermal protection-thermal insulation-thermal management design method for area protection region under high heat flux of hypersonic vehicle. A high temperature experimental apparatus which was heating on the basement of the sample and with maximum temperature of 1500K(for 2 hour) was fabricated to test the active cooling capacity and efficiency. The cooling capacity of transpiration cooling thermal protection system was tested. The results indicate that the heat load eject capacity improved at last 70%, cooling capacity is 170-500kW/m2(for high temperature alloy) and the temperature of inner strucrure below boiling temperature of water(with traspiration cooling).A new method of appling spray cooling to metallic thermal protection was proposed for nose and leading edge of hypersonic vehicle. A novel spray cooling thermal protection system was design and fabricated using the method of integrated thermal protection-thermal insulation-thermal management design method. An oxyacetylene experiment platform was design and fabricated and the experiment of cooling capacity of spray cooling thermal protection system was conducted.更多还原