火箭升空大热流下低温贮箱热分层仿真研究

Simulation Study on Thermal Stratification inside Cryogenic Tank under High Heat Flux Condition of Vehicle Launching

为揭示运载火箭裸壁贮箱内低温推进剂的温度场分布,建立了涵盖流体区与固壁区的耦合仿真模型,实现了地面预增压、升空气动加热、升空增压排液过程的连续预示,对比研究了贮箱侧壁是否绝热对箱内热分层与增压规律的影响。结果表明:预增压阶段的增压效果与箱内气枕区的热力学状态密切相关,延长预增压过程有利于减弱后期压力衰减幅度;裸壁贮箱升空阶段的气动加热会产生强烈的自然对流与热分层,影响液氧温度品质,箱内液氧最高温度可超过93 K;贮箱采用发泡绝热后可显著减弱升空气动热对箱内低温推进剂温度品质的影响。研究工作可为未来火箭低温贮箱的绝热方案设计提供指导。

To reveal the temperature field distributions of the bare-wall cryogenic propellant tank during vehicle launch-ing,a coupling simulation model,including fluid region and solid wall region,was established to realize the continuous pre-diction of ground pre-pressurization,launching aerodynamic heating and pressurized discharge processes.The thermal strati-fication and pressurization performance inside a bare-wall tank and a foamed wall tank were compared.The simulation re-sults show that the pressurization effect in the pre-pressurization stage was closely related to the thermodynamic state in the ullage region of the tank.Aerodynamic heating in the lift-off process of the bare-wall tank could produce strong natural con-vection and thermal stratification,which further affected the temperature quality of liquid oxygen.The maximum tempera-ture of liquid oxygen in the tank might exceed 93 K.The effect of aerothermal heating on the temperature of cryogenic pro-pellant in the tank could be significantly reduced by using a foam insulation layer.Generally,the present research could pro-vide guidance for the design of thermal insulation scheme for rocket cryogenic tank in the future.