Research On Heat Performance Of Thermal Protection System On Hypersonic Vehicle By Using Phase Change Materials

Thermal protection system(TPS)on hypersonic vehicle can protect the aircraft during multiple launches for continuous operation.It is essential for the new generation of reusable reentry aircraft,and can significantly reduce launch costs and prevent instrument overheating.Among all kinds of TPSs,the multi-layer structure has received widespread attention due to its advantages of bearing structural loads and insulating high temperatures,and the thermal insulation materials applied in this system are generally for mild heating environments.Although phase change material(PCM)is barely considered for this system,its unique properties can improve the thermal performance of the TPS.This thesis proposes a concept of multilayer TPS which uses PCM as insulation,and the improvement of its heat performance has been confirmed through numerical studies.The study utilises Fluent to numerically test models without PCM and models using different PCMs for thermal insulation layers.Based on the multilayer heat transfer problem and phase change problem,the finite volume method and enthalpy method are employed to calculate thermal response of the proposed TPS.Two classic experimental cases are reproduced to verify the reliability of the numerical method and to select a more optimal calculation scheme.All models can be divided into two series,namely single-panel TPS and dual-panel TPS,and each series contains different sub-series models.In the single-panel series,it is found that in the severe aerodynamic environment of the hypersonic vehicle,models merely using traditional insulation materials cannot meet the temperature requirement of the system that the maximum temperatures of all parts in TPS are below their respective temperature limits.However,the addition of PCM can not only reduce the temperature of each layer in TPS lower than their contraints,but also can contribute to the optimal designs of each sub-series with the optimisition goals of areal density and total thickness.In the array series composed by double panels,the phenomenon of uneven heat transfer due to the existence of the gap located between two TPS panels is paid attention to.The investigation of heat performance improvement of the array system by introducing PCM mainly focuses on the temperature results both at the panel centre and at the gap.The presence of PCM improves the thermal performance of array TPS,and the PCM thickness as well as the PCM thermophysical properties can affect the system in various degrees.