热防护系统损伤容限分析

Damage Tolerance Analysis on Thermal Protection System

建立了含初始矩形损伤的热防护系统(Thermal protection system,TPS)气动热分析的CFD数值模型,分析结果表明损伤区域侧壁出现了很高的热流密度峰值,并且迎风面侧壁峰值高于背风面,而损伤区域底部热流密度却很低。利用分析获得的热流密度建立了含损伤和无损伤TPS的有限元传热分析模型。分析结果表明:损伤的存在导致防热瓦最高温度急剧上升,超过其材料能承受的极限温度(1 500℃),防热瓦首先失效,而损伤对机体最高温度影响较小。最后进行了TPS损伤容限分析,在防热瓦极限温度约束下,外部热流密度最大值从100kW/m2增加到140kW/m2,矩形损伤宽度最大容许值从22.7mm减小到12.6mm,而弧形损伤宽度最大容许值从34.6mm减小到25.1mm,即随着外部热流密度最大值增加,损伤宽度的最大容许值降低,并且相同外部热流密度水平下弧形损伤宽度的最大容许值大于矩形损伤。

The CFD numerical model is established to study the aerodynamic heating of thermal protection system(TPS)with initial rectangular damage.The high peak heat flux appears on the side walls of the damage area,and the peak heat flux on windward side is greater than that on the leeward side.But the heat flux on the bottom of damage area is very low.The finite element heat transfer analysis models of thermal protection systems with and without damage are established by using the heat flux calculated above.The damage results show that the maximum temperature of tile rises sharply,and it exceeds the ultimate temperature 1 500℃that tile can bear,so the failure occurs on the tile firstly.But the damage has little influence on the maximum temperature of structure.Finally,damage tolerance analysis on the TPS is conducted.The maximum admissible width of rectangular damage reduces from 22.7 mm to 12.6 mm,and that of arc damage reduces from 34.6 mm to 25.1 mm when the maximum value of external heat flux increases from 100 kW/m 2 to 140 kW/m 2 under the ultimate temperature of tile.This is,as the maximum value of external heat flux increases,the maximum admissible width of damage area reduces,and the maximum admissible width of the arc damage is greater than that of the rectangular damage under the same external heat flux level.