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为开展金星和火星探测器地面防热试验研究,通过对CO2气体平衡成分分析、喷管流场计算和风洞运行能力分析,评估了电弧风洞模拟探测器进入CO2大气环境时的防热试验能力。首先采用平衡常数法计算分析CO2气体在不同温度和压力下的平衡成分,接着利用一维等熵理想气体模型分析喷管内平衡流和冻结流2种流态下的流场参数,最后计算CO2介质运行时喷管出口的驻点参数,评估驻点压力和驻点热流的包络性能。结果表明:电弧风洞CO2介质运行时气流在加热器内含碳量高达30%,并可能在水冷壁上沉积,降低设备绝缘性能和换热效率,给设备安全运行带来隐患;在平衡流和冻结流2种流态下,喷管出口气流中均含有CO和O2,且CO含量高达50%,为保护下游的真空设备和人员安全,防止反应生成的CO浓度达到爆炸极限,给出了在扩压器补充惰性气体钝化的初步方案。
In order to carry out the ground-based heat-resistance test of Venus and Mars probes, the heat-resistance test of the arc-wind tunnel simulation probe into CO2 atmosphere was evaluated by analyzing the composition of CO2 gas balance, the calculation of nozzle flow field and the analysis of wind tunnel operation capability ability. Firstly, the balance constants method was used to calculate and analyze the equilibrium composition of CO2 gas at different temperatures and pressures. Then the one-dimensional isentropic ideal gas model was used to analyze the flow field parameters of balance flow and freezing flow in the nozzle. Finally, CO2 medium Stationary nozzle parameters at run-time nozzle exit to assess the envelope pressure and stagnation point heat envelope. The results show that when the CO2 flow in the arc wind tunnel is running, the flow of carbon in the heater reaches as high as 30% and may deposit on the water wall to reduce the insulation performance and heat transfer efficiency of the equipment, posing a potential hazard to the safe operation of the equipment. And freezing flow, the CO 2 and CO 2 contents are both contained in the outlet flow of the nozzle, and the CO content is as high as 50%. In order to protect the downstream vacuum equipment and personnel and prevent the concentration of CO generated by the reaction from reaching the explosion limit, The diffuser is supplemented with a preliminary scheme of inert gas passivation.