Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale, a new two-phase mixture model is developed by incorporating the local thermal non-equilibrium effect. Considering the low-pressure and high overload working conditions of hypersonic flying, the heat and mass transfer induced by capillary and inertial body forces are analyzed for sub-cooled, saturated and super-heated states of water coolant under varying saturation pressures. After the validation of the model, transient simulations for different external factors, including spatially-varied heat flux, coolant mass flux, time-dependent external pressure and aircraft acceleration are conducted. The results show that the vapor blockage patterns at the outlet are highly dependent on the injection mass flux value and the external pressure, and the reduced saturation temperature at low external pressure leads to early boiling off and vapor blockage. The motion of flying has a large influence on the cooling effect, as the inertial force could change the flow pattern of the fluid inside significantly. The comparison of the results from 2-D and 3-D simulations suggests that 3-D simulation shall be conducted for practical application of transpiration cooling, as the thermal protection efficiency may be overestimated by the 2-D results due to the assumption of an infinite width length of the porous plate.

中文翻译：

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高超声速热防护瞬态相变蒸腾冷却局部热非平衡修正模型

为了有效地模拟相变蒸腾冷却的瞬态过程，并揭示连续尺度上流体与多孔介质颗粒之间的对流机制，通过结合局部热非平衡效应，建立了一种新的两相混合物模型。考虑高超声速飞行的低压、高过载工况，对不同饱和压力下水冷却剂的过冷、饱和和过热状态进行毛细管力和惯性体力引起的传热传质分析。模型验证后，对不同外部因素进行瞬态模拟，包括空间变化的热通量、冷却剂质量通量、随时间变化的外部压力和飞机加速度。结果表明，出口处的蒸汽堵塞模式高度依赖于注入质量通量值和外部压力，低外部压力下饱和温度降低导致早期沸腾和蒸汽堵塞。飞行的运动对冷却效果影响很大，因为惯性力会显着改变内部流体的流动模式。 2-D 和 3-D 模拟结果的比较表明，蒸腾冷却的实际应用应进行 3-D 模拟，因为由于假设了 2-D 结果，热防护效率可能会被高估。多孔板的无限宽度长度。