IMECH-IR  > 高温气体动力学国家重点实验室
钝头体再入气固热耦合计算方法研究
英文题名A Coupling Calculation with Aerodynamic -Ablation and Thermal Response for nose-tip of Re-entry Vehicle
田保未1,2
导师龙丽平
2018-05-28
学位授予单位中国科学院大学
学位授予地点北京
学位名称硕士
学位专业固体力学
关键词耦合计算 碳基复合材料 烧蚀 网格移动 重映
摘要

    高超声速飞行器再入大气层的过程中气动加热非常严重,飞行器周围,特别是前缘的气动热环境极其恶劣。为了保证主体结构的正常工作,必须对气动热环境恶劣的地方进行防热处理。工程中较常使用的热防护方案是烧蚀热防护。准确计算烧蚀量的多少,确定烧蚀涂层的厚度是工程中烧蚀热防护设计的重要工作。防热材料的后退不仅与材料本身的烧蚀性能有关,飞行器周围的气动热环境对其也有很大的影响,气动条件、温度场和烧蚀三者互相影响,因此发展气动—烧蚀—温度场耦合计算的程序对于准确模拟烧蚀边界后退、确定防热材料厚度具有重要意义。

    本文发展了一套考虑气动、烧蚀和瞬态温度分布的耦合计算方法。首先将钝头体再入的飞行轨迹离散化,在每一个离散状态进行气动—烧蚀—传热耦合计算,得到在极小时间段内的烧蚀后退量,利用网格移动算法重新生成计算域并将旧网格量重映到新网格,再进行下一时间段迭代,依次计算每一时间段内的烧蚀量,以达到模拟烧蚀外形后退的目的。

    耦合计算中需要知道气动热参数。本文给出了利用工程算法快速计算钝头体周围气动热的算法和程序,对钝双锥模型和单锥模型周围的压力分布和热流分布作了计算,同时给出了精确数值模拟的结果。实现气动计算和烧蚀—热传导模块之间的数据交换。

    对于C/C复合材料的烧蚀性能作了具体分析,给出了基于平衡化学反应的烧蚀模型和程序,并利用本文的程序分析了烧蚀产物与温度、压强的关系。烧蚀模块改变了气动计算和热传导计算区域的边界,本文利用ALE方法中的相关技术,给出了网格刷新的算法和针对四边形单元的重映算法。

     在上述工作的基础上,本文针对特定的钝头体再入过程进行耦合模拟。分别利用工程算法和精确数值模拟两种方法来求解再入钝头体周围的气动力和气动热,并将气动结果传递给烧蚀—热传导模块进行耦合计算。计算结果表明,利用耦合计算的方法基本能得到与试验相接近的烧蚀外形。同时也分析了影响烧蚀外形的关键因素。
 

英文摘要

    Aerodynamic heating is exceedingly serious during the re-entry of hypersonic vehicles into the atmosphere, and the aerodynamic environment surrounding the aircraft, especially the front edge, is extremely harsh. In order to ensure the normal operation of the main structure, it is necessary to perform thermal protection on the places where the aerodynamic environment is intensely severe. Ablative thermal protection is one of methods which more commonly used in engineering. Accurately calculating the amount of ablation and determining the thickness of the ablative coating are important tasks in the design of ablative thermal protection in the project. The recession of ablative material is not only related to the ablation performance of the heat-resistant material itself, but also the aerodynamic thermal environment around the aircraft has a great influence on it.  The aerodynamic conditions, temperature field and ablation affect each other, so it is necessary to make a program which for the coupling calculation of the temperature field distribution, aerodynamic condition and ablation of carbon-based composite material is of great significance for accurately simulating ablation boundary recession and determining the thickness of the thermal protection material.

    This paper developed a set of coupled calculation methods considering the aerodynamic, ablation and transient temperature distributions. Firstly, the trajectory of the blunt body reentry is discretized, and the aerodynamic-ablation-heat transfer coupling calculation is performed in each discrete state to obtain the ablation recession amount in a very small time period, and the grid mobile algorithm is used to regenerate the calculation. The domain remaps the old grid quantity to the new grid, and then iterates for the next period of time to calculate the amount of ablation in each period in order to achieve the purpose of simulating ablation and receding.

    The aerodynamic thermal parameters need to be known in the coupling calculation. An engineering algorithm was used  to calculate the aerodynamic heat around the blunt body in the thesis. The pressure distribution and heat flow distribution around the blunt double cone model and the single cone model are calculated, and the results of accurate numerical simulation are given. Achieves pneumatic calculations and ablation-heat transfer module data exchange.

    The ablation performance of C/C composites was analyzed in detail. The ablation model and procedure based on the equilibrium chemical reaction were given. The relationship between the ablation products and the temperature and pressure was analyzed using the procedure of this paper. The ablation module changes the boundary between the aerodynamic calculation and the heat conduction calculation area. In this thesis, using the related technology in the ALE method, the algorithm of the grid refresh and the remapping algorithm for the quadrilateral element are given.

    Based on the above work, this paper simulates the reentry process of a specific blunt body. Two methods, engineering algorithm and numerical simulation, were used to solve the aerodynamic heat around the reentry blunt body, and the aerodynamic results were transferred to the ablation-heat conduction module for coupling calculation. The calculation results show that the approximate shape of the ablation profile can be obtained by the coupling calculation method. At the same time, the key factors affecting the ablation profile are also analyzed.


 

语种中文
文献类型学位论文
条目标识符http://dspace.imech.ac.cn/handle/311007/73184
专题高温气体动力学国家重点实验室
作者单位1.中国科学院力学研究所
2.中国科学院大学
推荐引用方式
GB/T 7714
田保未. 钝头体再入气固热耦合计算方法研究[D]. 北京. 中国科学院大学,2018.
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