喷注压降对Al/AP粉末火箭发动机工作特性影响研究

Investigation on Effects of Injection Pressure Drop on Al/AP Powder Rocket Motor Operation Characteristics

关键词:  Al/AP粉末  火箭发动机  比冲  气固两相流  热试  燃烧效率

Key words:  Al/AP powder  Rocket engine  Specific impulse  Gas-solid two phase flow  Fire test  Combustion efficiency

摘要:

为研究喷注压降对Al/AP粉末火箭发动机工作特性影响，在考虑喷管两相流动损失的情况下，通过理论计算分析了压强、氧燃比对Al/AP粉末火箭发动机比冲、绝热燃烧温度及凝相产物质量分数的影响。以此为基础确定了Al/AP粉末火箭发动机工作参数，搭建了Al/AP粉末火箭发动机试验系统，通过改变流化气质量流率和粉末推进剂储箱出口通流面积的方法研究不同喷注压降下Al/AP粉末火箭发动机的工作特性。结果表明，流化气质量流率大小对Al/AP粉末火箭工作过程存在一定的影响，过小会导致粉末推进剂供给卡顿，过大会导致发动机性能降低。与此同时，Al/AP粉末火箭动机工作过程中存在由粉末推进剂输运时滞导致的燃烧室压力振荡，而通过提高粉末推进的喷注压降可以有效抑制这一振荡。当前技术状态下，由于在Al/AP粉末火箭动机燃烧室设计、粉末推进剂高效喷注和离散等方面存在不足，Al/AP粉末火箭动机的实际性能与理论性能还存在一定偏差，试验中最高燃烧效率为69.79%。

Abstract:

In order to investigate the effects of injection pressure drop on Al/AP powder rocket motor operation characteristics， influences of pressure， oxidizer to fuel ratio on aluminum/ammonium perchlorate powder rocket motor’s specific impulse， adiabatic combustion temperature， and condensed phase mass fraction were analyzed through theoretic calculation with the consideration of nozzle two phase flow losses. Based on the calculation， design parameters of the motor were determined and by changing the fluidization gas mass flow rate as well as the powder propellant tank exit throttle orifice area， experimental study on the effects of injection pressure drop on the motor operation characteristics was conducted. The results show that the fluidization gas mass flow rate has a tremendous influence on the engines’ operating process， insufficient one will result in blocking of powder feeding and excess one will result in engine performance decrease. Meanwhile， there is a chamber pressure perturbation caused by the ‘time lag’ during powder feeding process， which can be restrained by increasing the powder injection pressure drop. Finally， under the current technology state， there still a big gap between practical performance and theoretic performance for the engine， which is caused by the insufficient level in combustion chamber design as well as the poor efficient in powder propellant injection and discrete， the highest combustion efficiency is 69.79% in the tests.