点火药盒开孔大小对点火燃气内流场特性影响

Influence of Ignition Cartridge Opening-size on Inner Flow-field Characteristics of Ignition Gas

为了保证阶梯多根的装药设计形式的火箭发动机点火过程的安全性与稳定性,研究了不同开孔大小点火药盒的火箭发动机点火过程的流场特性。采用FLUENT计算软件对不同开孔大小点火药盒的火箭发动机点火过程的内流场进行了三维数值仿真,分析了点火药盒开孔大小对点火过程流场特性的影响。不同开孔大小点火药盒的输出压强都大约在4 ms时达到最大,开孔面积占点火药盒端面积百分比为2.5%、3%、3.5%的3种工况分别对应的最大输出压强约为54.8 MPa、44.6 MPa、32.9 MPa;3种工况下燃烧室压强达到6 MPa时为推进剂点燃的压强,开孔面积百分比2.5%的点火药盒为6.6 ms,开孔面积百分比3%的点火药盒为7.1 ms,开孔面积百分比3.5%的点火药盒为8.2 ms。点火药盒开孔面积越小,所对应的输出压强越大,所需要达到推进剂点燃压强的时间越短。研究结果可为类似结构的固体火箭发动机点火试验点火药盒的设计提供参考。

In order to ensure the safety and stability of the ignition process of rocket motor with ladder-shaped multiple propellant,the flow-field characteristics during ignition of rocket motor with ignition cartridges of different opening sizes were studied.The numerical simulation of the full 3-D inner flow-field models for rocket motor with ignition cartridges of different opening sizes was carried out by using FLUENT calculation software.The influence of the ignition cartridge opening-size on the flow-field characteristics during ignition was analyzed.The output pressure of ignition cartridges with different opening sizes reaches maximum at about 4 ms.The maximum output-pressure is about 54.8 MPa,44.6 MPa and 32.9 MPa respectively for the three conditions of the opening-area percentage such as 2.5%,3%and 3.5%of the ignition cartridge transverse area.The pressure of 6 MPa in the combustion chamber under the three conditions is the propellant ignition pressure.The time to reach the propellant ignition pressure was 6.6 ms for the opening-area percentage of 2.5%,7.1 ms for the opening-area percentage of 3%,and 8.2 ms for the opening-area percentage of 3.5%.The smaller the opening area of the ignition cartridge,the greater the corresponding output pressure,and the shorter the required time to reach the propellant ignition pressure of combustion chamber.The research results offer reference for the design of ignition cartridge for ignition test of similar structure of solid rocket motors.