稀薄流航天器鼻锥迎风凹腔气动力和气动热性能研究

Aerodynamics and Aerothermodynamics Analyses of Space Vehicle Nose with Forward-Facing Cavity in Rarefied Flow

关键词:  航天器  鼻锥  稀薄流  凹腔  气动力  气动热  热流

Key words:  Space vehicle  Nose  Rarefied flow  Cavity  Aerodynamic  Aerothermodynamic  Heat flux

摘要:

为探究稀薄流流域迎风凹腔的气动防热特性，采用直接模拟蒙特卡罗（DSMC）方法，对稀薄流流域中航天器鼻锥迎风凹腔气动力与气动热性能进行了研究。得到了鼻锥外壁面、凹腔侧壁面以及凹腔底面的热流密度分布情况，分析了不同凹腔深宽比对鼻锥冷却效率以及凹腔腔体内气体参数的影响。以深宽比为1的凹腔为基准，研究了凹腔唇口钝化半径对航天器气动热与气动力的影响。数值结果表明，稀薄流流域中迎风凹腔能够使鼻锥外壁面的热流密度下降7%左右；当凹腔深宽比达到1之后，凹腔侧壁面热流变化趋于一致，热流密度最低点的轴向位置不随深宽比改变，且凹腔底部热流很小，仅为L/D=0.5算例的28.66%；凹腔近底部气体均由稀薄流转化为连续流，凹腔内气体压力不断振荡；唇口钝化没有明显优势，虽然可以降低鼻锥峰值热流，但是会带来严重的气动力性能下降。

Abstract:

To investigate the thermal protection characteristics of forward-facing cavity in rarefied flow， a numerical study in aerodynamic and aerothermodynamics performance on the space vehicle applying the forward-facing cavity in rarefied flow was conducted via Direct Simulation Monte Carlo （DSMC） method. Heat flux distributions along the nose outer wall surface， cavity side wall surface and cavity base wall surface were obtained， afterwards， the thermal-cooling effect and the gas conditions in the forward-facing cavity with different length-depth ratios were analyzed. Moreover， on the basis of the model with length-depth ratios of 1， the variation in the aerodynamic and aerothermodynamics performance with nose lip bluntness radius was quantified to study the effect. The results show that the outer wall surface bears approximately 7% lower heat flux by creating a forward-facing cavity. When the length-depth ratio reaches 1， the trend of heat flux distributions along the cavity side wall surface is very similar， and the axial position where the heat flux drops to the lowest point no longer changes， meanwhile the heat flux along the cavity base wall surface is very small， which is only 28.66% of the model with length-depth ratios of 0.5. The gas near the bottom of the cavity changes from rarefied flow to continuous flow and the gas pressure oscillates. In conclusion， there would be no apparent advantages of heat reduction due to the great increment of drag coefficient employing cavity lip bluntness. Although it can reduce peak heat flux， it would result in more severe aerodynamic degradation.