固液混合火箭发动机固体燃料的燃速计算

Computation of fuel regression rate in classical hybrid rocket motors

分析了固液混合火箭发动机的燃烧特点、燃烧中气相过程和固体燃料内部的传热过程,利用由传热理论得出的固体燃料燃速公式和阿累尼乌斯(Arrhenius)燃速公式耦合计算,得到了燃速与氧化剂流率、轴向距离、装药初温和时间的变化规律.计算结果表明固体燃料燃速主要受氧化剂流率和轴向距离的影响,随氧化剂流率的增加而增加,随轴向距离的增加而减小.固体燃料燃速温度敏感性小,在设计发动机时可以不考虑装药初温的影响.利用热力计算得到了绝热燃烧温度与氧化剂流率和药柱长度的变化规律,绝热燃烧温度随氧化剂流率的增加存在一最大值.计算结果与相关文献的报道比较吻合,为进一步研究固液混合火箭发动机的燃烧及流动问题打好了基础.

The combustion characteristic in classical hybrid rocket motors has been studied. The heat transfer process in the gas and the solid fuel has been considered. Coupling computation is presented by the regression rate equations based on the heat transfer theory and the Arrhenius law. The regression rate at various oxidizer mass flow rates, axis distances, ambient operating temperatures and times is obtained. Fuel regression rate mainly infects with oxidizer mass flow rate and axial distance. Regression rate increases as oxidizer mass flow rate increases and decreases as axial distance increases. The temperature sensitivity of solid fuel in a hybrid rocket motor is low and we need not assign a weight margin for variations in ambient operating temperatures. Adiabatic combustion temperature at various oxidizer mass flow rates and grain length is obtained by thermodynamic calculation and has a maximum as oxidizer mass flow rate increases. The results are in agreement with the some references and useful for further study.