采用高金属粉丁羟推进剂消氢发动机低压点火燃烧特性研究

Study on the ignition and combustion characteristic ofhydrogen-eliminated motor with high metal powder content HTPB propellant

发展了一种采用新型高金属粉丁羟推进剂消氢发动机,该发动机可通过产生高温金属粒子流,消除以液氢为燃料的火箭发射前排出的低温氢气的危险。该发动机在小于0.2 MPa特低压下工作时,存在点火延迟、“喘振”不稳定燃烧和火焰无金属粒子流现象。分析了引起发动机点火延迟和“喘振”的原因;从理论上探讨了影响低压下发动机点火延迟的因素,得到换热系数影响最显著;通过引入高燃速引燃药和降低点火峰值压强,解决了发动机点火延迟和“喘振”的问题,发动机点火延迟时间由大于3 s降低到600 ms左右,发动机燃烧稳定;通过选用合适的金属粒子、推进剂配方燃温和长尾管结构,解决了金属粒子流发生问题,可稳定喷射出1141 K的高温金属粒子流,实现了消除火箭周围低温氢气的目的。

A new type of hydrogen-eliminated motor with high content metal powder HTPB propellant was developed.By producing high temperature of metal powder stream,the motor which can eliminate the risk of low temperature hydrogen released from rocket which contain LH 2 as fuel before rocket launch.Worked at very low pressure as below 0.2 MPa,the motor existed the phenomena of ignition delay,“gasp”unsteady combustion and no metal powder stream in flame.The phenomena of ignition delay and“gasp”unsteady combustion were analyzed.Factors of the causing of ignition delay at low pressure were discussed theoretically,and it was found that the coefficient of heat transfer was the most prominent factor.The difficulties of ignition delay and“gasp”unsteady combustion were overcome by introducing a high burning rate ignite propellant and by reducing the igniter peak pressure.By these methods,the ignition delay time reduced from more than 3 s to about 600 ms and the motor burned steadily.The problem of no metal powder stream in flame was tackled by selecting right metal powder,propellant formula with suitable combustion temperature and long tail pipe.The motor could produce 1141 K high temperature metal powder stream in flame,and the aim to eliminate low temperature hydrogen around rocket was attained.