UDMH/NTO富氧燃气发生器预点火过程模型研究及应用

Investigation and application of pre-ignition process model of a UDMH/NTO oxidizer-rich gas generator

对富氧燃气发生器中偏二甲肼/四氧化二氮(UDMH/NTO)推进剂的自燃点火特性开展实验研究,结果表明,燃气发生器点火初期能量低,燃气温度缓慢爬升。基于实验结果和化学机理分析,构建了描述UDMH/NTO自燃推进剂在富氧环境下预点火过程的热力学模型,并将其应用到实验系统的系统级仿真模型中。实验结果验证了仿真模型的合理性,动态相对误差小于15%,主要差异在于燃气发生器压力“平台段”的仿真值偏低。在此基础上开展仿真研究,结果表明:初始参数变化明显影响点火初期的性能参数爬升特性,其中延长点火时差至2倍、将入口压力降低0.05 MPa或者将推进剂温度降低15℃均会导致发动机起动加速性降低25~50 ms,而提高入口压力和缩短点火时差可以减轻推进剂温度变化对性能参数爬升特性的影响程度。

The spontaneous ignition characteristics of UDMH/NTO propellant in oxidizer-rich gas generator were experimentally studied,and the results show that the initial energy of the gas generator ignition is low,and the gas temperature climbs slowly.Based on the experimental results and chemical mechanism analysis,a ther-modynamics model describing the pre-ignition process of UDMH/NTO propellant in oxidizer-rich environment was constructed,then applied it to the system level simulation model for the experimental system.The compari-son with experimental results verifies the rationality of the simulation model,and the dynamic simulation errors are less than 15%.The main difference is due to simulation value of the gas pressure platform section of the gas generator being low.Based on this simulation analysis,the results show that the initial parameter change obvious-ly affect the performance parameters climb characteristics in the initial stage of ignition,and the starting accelera-tion is reduced by 25~50 ms,by prolonging the ignition time difference to 2 times,reducing the inlet pressure by 0.05 MPa or propellant temperature by 15℃.Increasing the inlet pressure and shortening the ignition time differ-ence can reduce the effect of propellant temperature changes on the performance parameter climb characteristics.