International Journal of Heat and Mass Transfer ( IF 5.2 ) Pub Date : 2021-06-06 , DOI: 10.1016/j.ijheatmasstransfer.2021.121482 Obinna Uyanna , Hamidreza Najafi , Bhuvaneswari Rajendra
Space vehicles experience extremely high aerothermal heating during atmospheric entry which necessitates the use of appropriate thermal protection system (TPS). Effective design of TPS and the health monitoring systems (HMS) for space vehicles requires accurate flight data during atmospheric entry process. While direct measurement of the surface heat flux is a very challenging task, an alternative approach is to use the measured temperature values from the inner layers and solve the associated inverse heat conduction problem (IHCP) in order to estimate the surface heat flux. In the present paper, a solution approach is developed based on filter form of Tikhonov regularization method for near real-time calculation of surface heat flux in a one-dimensional medium consists of three layers that represents an integrated thermal protection system (ITPS). The solution is evaluated through numerical test cases developed in ANSYS and using experimental data from the literature. A parametric study is also conducted in order to understand the effect of sensor location (two layers and three layers models) as well as the effect of temperature dependent material properties on the performance of the solution. It is found that the developed solution estimates the surface heat flux with an average RMS error of about 1.96 and 3.44% for the two layer models with constant and temperature dependent material properties respectively. For the three layer model, the average RMS values are found for the constant and temperature dependent material properties as 2% and 4.44% respectively. It is also shown that the developed solution can evaluate the surface heat flux with 17 and 80 s delay for the two and three layers domain respectively, facilitating a near-real time operation for the inverse solution algorithm that can support the development of HMS for space vehicles or other industrial applications with the need for heat flux monitoring. The proposed solution technique is fast, accurate and very convenient to implement even for complex problems involving large temperature variations and temperature dependent material properties.
中文翻译:
航天器热保护系统气热加热实时估计的逆方法
航天器在进入大气层时会经历极高的空气热加热,这需要使用适当的热保护系统 (TPS)。航天器的 TPS 和健康监测系统 (HMS) 的有效设计需要在大气进入过程中提供准确的飞行数据。虽然直接测量表面热通量是一项非常具有挑战性的任务,但另一种方法是使用从内层测量的温度值并解决相关的逆热传导问题 (IHCP) 以估计表面热通量。在本文中,基于 Tikhonov 正则化方法的滤波器形式开发了一种求解方法,用于近实时计算一维介质中的表面热通量,该介质由三层组成,代表集成热保护系统 (ITPS)。该解决方案通过在 ANSYS 中开发的数值测试案例并使用文献中的实验数据进行评估。还进行了参数研究,以了解传感器位置(两层和三层模型)的影响以及温度相关材料属性对解决方案性能的影响。发现开发的解决方案估计表面热通量的平均 RMS 误差约为 1.96% 和 3.44%,分别适用于具有恒定和温度相关材料属性的两层模型。对于三层模型,常数和温度相关材料属性的平均 RMS 值分别为 2% 和 4.44%。还表明,所开发的解决方案可以分别评估两层和三层域的 17 秒和 80 秒延迟的表面热通量,促进逆解算法的近实时操作,可以支持空间 HMS 的开发需要热通量监测的车辆或其他工业应用。即使对于涉及大温度变化和温度相关材料特性的复杂问题,所提出的求解技术也快速、准确且非常方便地实施。