FLUX-BASED FINITE-VOLUME FORMULATIONS AND ADAPTIVE TIME-STEPPING STRATEGIES FOR MODELING OF REENTRY THERMAL PROTECTION SYSTEMS

1996 ◽  
Vol 30 (2) ◽  
pp. 117-136 ◽  
Author(s):  
Ram V. Mohan ◽  
Kumar K. Tamma ◽  
Antonio F. Avila
2020 ◽  
pp. 10-21
Author(s):  
V. G. Babashov ◽  
◽  
N. M. Varrik ◽  

The emergence of new types of space and aviation technology necessitates the development of new types of thermal protection systems capable of operating at high temperature and long operating times. There are several types of thermal protection systems for different operating conditions: active thermal protection systems using forced supply of coolant to the protected surface, passive thermal protection systems using materials with low thermal conductivity without additional heat removal, high-temperature systems, which are simultaneously elements of the bearing structure and provide thermal protection, ablation materials. Heat protection systems in the form of rigid tiles and flexible panels, felt and mats are most common kind of heat protecting systems. This article examines the trends of development of flexible reusable heat protection systems intended for passive protection of aircraft structural structures from overheating.


2020 ◽  
Vol 10 (8) ◽  
pp. 2790
Author(s):  
Wenzheng Zhuang ◽  
Chao Yang ◽  
Zhigang Wu

Hybrid corrugated sandwich (HCS) plates have become a promising candidate for novel thermal protection systems (TPS) due to their multi-functionality of load bearing and thermal protection. For hypersonic vehicles, the novel TPS that performs some structural functions is a potential method of saving weight, which is significant in reducing expensive design/manufacture cost. Considering the novel TPS exposed to severe thermal and aerodynamic environments, the mechanical stability of the HCS plates under fluid-structure-thermal coupling is crucial for preliminary design of the TPS. In this paper, an innovative layerwise finite element model of the HCS plates is presented, and coupled fluid-structure-thermal analysis is performed with a parameter study. The proposed method is validated to be accurate and efficient against commercial software simulation. Results have shown that the mechanical instability of the HCS plates can be induced by fluid-structure coupling and further accelerated by thermal effect. The influences of geometric parameters on thermal buckling and dynamic stability present opposite tendencies, indicating a tradeoff is required for the TPS design. The present analytical model and numerical results provide design guidance in the practical application of the novel TPS.


2018 ◽  
Vol 140 (9) ◽  
Author(s):  
R. Maffulli ◽  
L. He ◽  
P. Stein ◽  
G. Marinescu

The emerging renewable energy market calls for more advanced prediction tools for turbine transient operations in fast startup/shutdown cycles. Reliable numerical analysis of such transient cycles is complicated by the disparity in time scales of the thermal responses in fluid and solid domains. Obtaining fully coupled time-accurate unsteady conjugate heat transfer (CHT) results under these conditions would require to march in both domains using the time-step dictated by the fluid domain: typically, several orders of magnitude smaller than the one required by the solid. This requirement has strong impact on the computational cost of the simulation as well as being potentially detrimental to the accuracy of the solution due to accumulation of round-off errors in the solid. A novel loosely coupled CHT methodology has been recently proposed, and successfully applied to both natural and forced convection cases that remove these requirements through a source-term based modeling (STM) approach of the physical time derivative terms in the relevant equations. The method has been shown to be numerically stable for very large time steps with adequate accuracy. The present effort is aimed at further exploiting the potential of the methodology through a new adaptive time stepping approach. The proposed method allows for automatic time-step adjustment based on estimating the magnitude of the truncation error of the time discretization. The developed automatic time stepping strategy is applied to natural convection cases under long (2000 s) transients: relevant to the prediction of turbine thermal loads during fast startups/shutdowns. The results of the method are compared with fully coupled unsteady simulations showing comparable accuracy with a significant reduction of the computational costs.


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