摘要
本文对航天飞机机头的碳-碳热防护层,在再入的气动加热条件下,采用气动热化学烧蚀模型建立烧蚀方程,采用单元体能量平衡法建立各向异性、变物性材料的瞬态热传导方程,通过坐标变换处理烧蚀移动边界,并从物理平面转换到计算平面中去,然后成功地进行了烧蚀和温度场的耦合求解。计算结果表明了航天飞机机头碳-碳热防护层中的烧蚀和温度分布规律。
The reentry thermo-protection problem of space shuttle was solved mainly through well-conducted experiments. Chinese engineers now find it feasible and more efficient to supplement experiments with theoretical analysis. This paper presents a method for calculating ablative rate and internal temperature distribution of C-C nose cap of space shuttle. Theoretical analysis of C-C nose cap must overcome two main difficulties. These two difficulties are: 1)Heat-conduction is under moving boundary condition. With aerodynamic heating, the ablative consumption of material causes the thickness of thermo-protective layer to become thinner and thinner, resulting in continuously changing of heat-conduction pattern from body surface into its interior. Thus, heat-conductive calculation should take into account the rather difficult problem of moving boundary. 2)With aerodynamic state and thermo-protectiv material previously determined, wall temperature is the decisive factor influencing ablation, but wall temperature itself is much influenced by the heat conducted to structure. On the other hand, the degree of severity of ablation affects not only thermo-effect terms but also the speed of motion of moving boundary and consequently heat-conduction. In other words, ablation and heat-conduction are coupled, and this presents considerable difficulty which must be overcome in theoretical analysis. Besides, material anisotropy and physical properties that change with temperature also make calculations more difficult. In this paper, we establish equations of ablative outline and ablative rate on the basis of aerodynamic-thermochemical model, employ energy balancing method to establish transient heat-conductive equation that takes into account anisotropy and changing physical properties, treat properly the ablative moving boundary through coordinate transformation, and finally, successfully carry out the solution of coupled ablation and heat-conduction. Calculated distributions of ablative rate and temperature in C-C nose cap of shuttle are presented in Figs. 3(b) through . Preliminary tests indicate that our method of calculation shows good promise for perfecting calculations that are in agreement with experimental data.
出处
《西北工业大学学报》
EI
CAS
CSCD
北大核心
1992年第4期550-558,共9页
Journal of Northwestern Polytechnical University
基金
航空航天部基金
国家863计划资助项目
关键词
航天飞机
烧蚀
机头
热防护层
shuttle nose cap
ablation
temperature field
