【作者】 孙健；

【导师】 刘伟强；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2013， 博士

【摘要】 高超声速飞行器工作时前缘将处于恶劣的热环境中，为保证其外形尖锐的特性，本文提出前缘疏导式热防护结构。疏导式热防护作为一种半被动热防护方式，与传统的烧蚀热防护机制不同，它采用高导热率材料、高效传热元件的传热、对流换热的物理特性将高热流区的热量快速传递到低热流区，并借助大范围的低温散热面将热量以辐射的方式释放，降低高热流区的表面温度，以达到现有耐高温材料能够承受的水平。本文针对高超声速飞行器前缘的疏导式热防护系统展开研究，首先建立了高超声速飞行器前缘流场的数值计算模型，通过与公开文献中壁面热流的实验结果以及采用超声速流动的高分辨率NPLS流场观测技术的流场显影实验结果进行对比，证实其计算结果与实验结果具有较好的吻合性，证明了所建立数值计算模型的可靠性。针对给定高超声速飞行器前缘进行了气动热分析，为前缘疏导式防热结构工作机理的分析提供了准确的热环境条件。根据热弹性力学的基本关系和传热学的研究方法，对高超声速飞行器前缘内嵌高导热率材料的疏导结构工作原理进行分析。分别对给定工况下高超声速飞行器头锥与翼前缘疏导式结构的防热效果进行了分析，对比了有无疏导结构时头锥与翼前缘的热力（温度、温度梯度与热应力）分布情况。内嵌高导热率材料的疏导结构实现了热量由高温区向低温区的转移，降低了高热流密度区的温度，提升了结构的整体辐射散热能力，实现了对前缘高温区的热防护。在高超声速飞行器头锥和翼前缘疏导式结构防热效果影响因素方面，分别讨论了高导热层厚度、高导热层弦向长度、高导热层导热系数、蒙皮表面黑度、气动加热载荷及接触热阻对防热效果的影响，为前缘疏导式结构设计和材料选取提供依据。为了研究前缘内嵌高温热管疏导式结构的工作原理，本文首先对常规的液态金属热管内部流动与换热情况进行建模分析。针对工质为液态金属的圆管热管的工作原理和特性，将吸液芯及其内部金属液体等效为一固体层，建立热管蒸汽腔内部流动与换热控制方程，将复杂的热管内部流动换热相变过程简化。采用所建热管工作模型对固定构型的液态金属热管进行分析，并与实验结果进行对比，验证模型具有较好的准确性。本文还根据液态金属热管的特性，分析了其传热极限，以及热管结构参数和工质种类对传热极限的影响。对高超声速飞行器前缘内嵌高温热管结构的最佳防热效果进行了分析，阐述了前缘结构中热管工作温度分析方法和热管蒸汽腔假定为超高导热率虚拟材料的分析方法。采用液态金属高温热管的分析方法，对弯曲前缘结构的二维防热机理进行了建模，分析单边吸液芯条件下热管的工作情况，对比了有无热管结构时前缘的温度分布情况，证明了前缘内置高温热管确实能够将头部驻点区域的热量转移至低温翼面，进而降低前缘头部温度，实现对飞行器前缘的热防护。根据前缘内嵌热管结构的二维分析方法，进一步对前缘内置高温热管结构进行三维立体建模，将热管考虑为矩形结构，并分析相应边界条件，对前缘内置热管结构进行一体化数值模拟，进一步讨论了该结构最佳防热效果的影响因素，包括高温热管的宽度与长度、蒙皮外壁面黑度以及热管与蒙皮之间的接触热阻。根据现有前缘内嵌高温热管结构容易出现的问题，提出一种一体化前缘热管结构，并对该结构进行详细介绍。一体化前缘热管结构的吸液芯由矩形槽道构成，其蒸汽腔中含有毛细材料制成的柱体，它能在提供毛细力的同时起到支撑蒸汽腔的作用。由于一体化前缘热管结构内部流动与换热情况十分复杂，考虑其高导热性，进而将其蒸汽腔等效为一高导热固体层，吸液芯依据固-液混合体进行导热情况分析。根据一体化前缘热管结构的特性，研究了该前缘热管结构的传热极限（声速极限、毛细极限和沸腾极限），并分别对工质为Na和Li时，不同工作温度的前缘内嵌热管结构的适用性进行了讨论。根据高超声速飞行器前缘两类疏导式防热结构，分别设计了内嵌铜材料的钢质前缘实验件以及一体化层板式热管前缘实验件。通过球形短弧氙灯辐射加热前缘，测量前缘采用疏导结构前后的温度分布，验证了前缘疏导式防热结构的防热效果。更多还原

【Abstract】 The dredging thermal protection structure (DTPS) is considered as thermalprotection system to prevent hypersonic vehicle whose leading edge should remainsharp outline at work from the serious aerodynamic heating. Dredging thermalprotection which is semi-passive thermal protection is different from the traditionalablation thermal protection system mechanism. Using heat transfer and heat convectionphysical properties of high thermal conductivity materials and high-performance heattransfer elements, it transfers heat power from high heat flux region to low one. Andthen the severe aerodynamic heating is released by radiating through a large number oflow heat flux area. It reduces local stagnation temperature sufficiently to allow the useof superalloy materials.The work in this thesis is about the mechanism of hypersonic vehicle’s DTPS. Thenumerical calculation model of hypersonic vehicle leading edge’s flow field isestablished. And the numerical calculation result is contrast with the wall heat flow ofopen experiment and the flow field distribution which is got by high-definition NPLSthat is observation techniques of hypersonic flow. The comparison results can approvethe numerical calculation model has good accuracy. The aerodynamic heating ofhypersonic vehicle’s leading edge can provide correct thermal environment conditionfor the research of mechanism of DTPS.According to the thermal elastic mechanics and classic heat transfer, thefundamental of hypersonic vehicle’s leading edge embedded high thermal conductivitymaterials is studied. Both nose cone and wing leading edge of hypersonic vehicle’sDTPS are researched under given condition. The distributions of thermal forceconditions which include temperature, temperature gradient and thermal stress arecontrasted when the leading edge structure has DTPS or not. Achieving the transfer ofheat from high temperature region to low one, the temperature of high heat flux area isreduced and the radiation cooling ability of integral DTPS is strengthened. The thermalprotection for the leading edge’s high temperature region is obtained. The influencingfactors which contain the thickness, length and thermal conductivity of highconductivity material layer, the black level of coating surface, the thermal load and thecontact thermal resistance of hypersonic vehicle leading edge’s DTPS to thermalprotection effect are discussed. These factors can provide a frame of reference for thedesign of structure and the selection of materials.For researching the mechanism of DTPS which has been embedded hightemperature heat pipe, the flow and heat transfer model of conventional liquid metalheat pipe has been built. Against the working principle and characteristics ofconventional liquid metal heat pipe, the wick and internal liquid metal are considered as a solid layer during the studying model. The complex flow and heat transfer processduring the heat pipe have been simplified. And its result is contrasted with experimentdata which can approve it has good accuracy when the working fluid is liquid metal.The heat transfer limits of conventional liquid metal heat pipe and their influencingfactors have been studied.Using the analytical methods of working temperature of heat pipe and consideringvapor chamber as high thermal conductivity virtual material, the best thermal protectioneffect of hypersonic vehicle leading edge’s DTPS which has been embedded hightemperature heat pipe has been researched. The two-dimension thermal protectionmechanics of curving leading edge’s DTPS is studied by using the analytical procedureof high temperature liquid metal heat pipe. The temperature distribution re contrastedwhen the leading edge structure has DTPS or not. Achieving the transfer of heat fromhead to after-body, the front head of the thermal load is weakened and the ability ofleading edge thermal protection is strengthened. The three-dimension integral model ofleading edge’s DTPS has been established when the cross section of heat pipe isconsidered as rectangle. Then the best thermal protection effect’s influencing factorswhich contain the width and length of heat pipe, the black level of coating surface andthe contact thermal resistance between heat pipe and coating are discussed.The integral heat-pipe-cooled leading edge structure (IHPCLE) is considered asthermal protection system to solve the questions which present leading edge’s DTPSalways have. The wick of IHPCLE composes by rectangle channel. The vapor chambercontains cylinder which is made up by capillary material to support structure and toprovide capillary force. As the complex flow and heat transfer process during theIHPCLE, the vapor chamber of IHPCLE is considered as a high thermal conductivitysolid layer and the wick and internal liquid metal is considered as compound body. Theheat transfer limits of IHPCLE are studied. When the working fluid is Na and Li, theapplicability of IHPCLE is researched under different working temperature.According to the DTPS of leading edge, both the structure of embedded coppersteel leading edge and IHPCLE system are designed. Using the xenon lamp as heatsource, the dredging thermal protection effect are proved though measuring thetemperature of leading edge which has DTPS or not.更多还原