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为了准确地分析以不同燃料为冷质的换热器预冷空气涡轮火箭发动机的性能,本文建立了可考虑工质组分化学平衡与工质热物性随温度和压力变化的热力循环模型。利用该模型分析了以LH2、LCH4和煤油为燃料的发动机循环性能,研究了预热温度、燃气发生器和主燃室出口温度对循环性能的影响。结果表明,换热器预冷能够降低压气机进口温度,减小相同增压比下的压缩功,提高燃料温度,减小推进剂流量,从而减小燃空比,增加比冲;燃料预热温度的提高可减小燃气发生器氧燃比,进而减小燃空比、增大比冲;较低的燃气发生器和主燃烧室出口温度可降低燃空比,提高比冲,但会造成单位推力的下降。同时,研究结果还表明,与LCH4和煤油相比,LH2的比热容与热值的比值最大,采用LH2预冷的发动机的飞行速度和比冲的增幅也最大,说明比热容与热值的比值越大,相应的预冷效果越好,即可依据燃料比热容与热值的比值定性衡量发动机的预冷效果。
In order to accurately analyze the performance of precooling air turbine rocket motors with different fuels, the paper establishes a thermodynamic cycle model that considers the chemical composition of the working fluid and the thermal properties of the working fluid with temperature and pressure. The model was used to analyze the cycle performance of engine with LH2, LCH4 and kerosene as fuel, and the influence of preheating temperature, outlet temperature of gas generator and main chamber on the cycle performance was studied. The results show that the precooling of the heat exchanger can reduce the inlet temperature of the compressor, reduce the compression work under the same supercharging ratio, increase the fuel temperature, reduce the flow of the propellant, so as to reduce the air-fuel ratio and increase the specific impulse; Increasing the temperature reduces the oxygen to gas ratio of the gas generator, which in turn reduces the air-fuel ratio and increases the specific impulse; lower gas generators and the main combustor outlet temperature reduce the air-fuel ratio and increase the specific impulse, Decline in thrust. At the same time, the results also show that, compared with LCH4 and kerosene, LH2 the ratio of specific heat capacity and calorific value of the maximum LH2 precooling engine flight velocity and impulse increase is also the largest, indicating the ratio of specific heat capacity and calorific value , The corresponding pre-cooling effect is better, you can qualitatively measure the pre-cooling effect of the engine based on the ratio of specific heat capacity and heating value of the fuel.