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金属结构航天器陨落过程三维瞬态传热有限元算法研究
Study on finite element algorithm for three dimensional transient heat transfer during falling reentry of spacecraft with metal truss structure
投稿时间:2017-11-29  修订日期:2018-02-05
DOI:
中文关键词:  金属桁架结构航天器  陨落再入  三维瞬态传热  有限元计算模型
英文关键词:Spacecraft with metal truss structure  falling reentry from the outer space  3-dimensinal transient heat transfer  finite-element computational model
基金项目:
作者单位E-mail
石卫波 中国空气动力研究与发展中心 38758928@qq.com 
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中文摘要:
      构建金属桁架结构航天器陨落再入气动热环境有限元传热模型,是准确预测在轨服役期满大型航天器陨落再入解体过程温度分布的关键。本文采用四节点四面体单元对空间进行离散,依据泛函理论,将传热控制方程离散为代数方程组;利用有限单元法总体合成得到具有对称正定、高度稀疏、非零元素分布的规则性刚度矩阵,发展一维变带宽压缩存贮技术,有效解决大型稀疏矩阵的数据存贮问题;为有效抑制求解过程出现的温度在时间和空间上的振荡问题,发展集中热容矩阵系数处理方法,将热容矩阵的同行或同列元素相加代替对角线元素,使非对角线元素化为零,构造求解三维瞬态温度场的两点向后差分格式、Crank-Nicolson格式和Galerkin格式。通过对长方柱体瞬态传热计算验证分析,在相同条件下,采用以上三种格式均可获得一致稳定的温度解,并得到与现有ANSYS有限元软件较为吻合的计算结果,确认所建立三维瞬态传热有限元计算模型的准确可靠性。在此基础上,对铝合金低轨航天器薄壳结构进行了传热计算,给出了类天宫飞行器两舱体陨落飞行107.5km~90km不同高度的瞬态温度分布,为这类寿命末期航天器陨落再入解体预报提供理论支撑与可计算模型。
英文摘要:
      To construct the finite element model for the heat transfer of the large-scale complex spacecraft with metal truss structure during reentry aerothermodynamics environment, is the key to accurately predict the temperature distribution of the end-of-life spacecraft during the process of falling reentry and disintegration. In this paper, the four-node tetrahedron element is used to discretize the space, and the heat transfer equation is discretized into the algebraic equation sets. The stiff matrix with symmetrically positive, highly sparse and non-zero element distribution is obtained by the overall synthesis of the finite element method. The one-dimensional variable bandwidth storage technique is developed to effectively resolve the data storage of large sparse matrix. To effectively depress the temperature oscillations appeared in time and space in the solving process, the centralized heat capacity matrix coefficient method is developed. The same row or column elements of the heat capacity matrix are summed and substituted by the diagonal elements, so that only the diagonal elements of the new heat capacity matrix exist, and the remaining elements are zero. The two-point backward difference scheme, Crank-Nicolson scheme and Galerkin scheme are constructed to solve the three-dimensional transient temperature field. By computational analysis of transient heat transfer of the rectangular cylinder body, the converged temperature solutions of the above-said three schemes are in good agreement, and the results are consistent with that of the existing finite-element ANSYS software, which confirms the precision and reliability of the present 3D finite-element model for transient heat transfer. The heat transfer computation is carried on the shell structure of the low-orbit spacecraft made of aluminium alloy, and the transient temperature distribution of the Tiangong’s two-capsule structure is simulated and analyzed from the flight altitude of 107.5km~90km, which provides the theoretical support and computable model for the forecast of disintegration of the end-of-life spacecraft during falling reentry.
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