双脉冲固体火箭发动机Ⅰ脉冲燃烧室壁面烧蚀特性研究

Ablation characteristics research on combustor wall ofⅠpulse in dual pulse solid rocket motor

针对双脉冲固体火箭发动机Ⅰ脉冲燃烧室壁面烧蚀热防护问题,基于热解动力学和热化学烧蚀理论,建立了芳纶/三元乙丙橡胶(EPDM)变热物性传热烧蚀模型,结合Ⅰ脉冲燃烧室绝热层工作过程的热载荷环境分布特征,开展了Ⅰ脉冲绝热材料与钢壳体一体化传热烧蚀研究,分析了不同脉冲间隔时间、不同脉冲工作时间对绝热层烧蚀特性的影响。研究结果表明:热流作用初期绝热材料表面升温迅速,但温度上升速率和炭化层厚度增长速率随能量扩散不断降低;Ⅱ脉冲工作时,Ⅰ脉冲绝热层烧蚀严重区域与气流剪切力极大值区域对应;不考虑炭化层整体剥落的前提下,脉冲间隔时间越长,Ⅰ脉冲绝热层烧蚀厚度越小,但Ⅰ脉冲燃烧室壳体温度越高,越容易影响发动机结构完整性;脉冲工作时间越长,烧蚀厚度增加速率越小;双脉冲发动机工作时间一定时,Ⅱ脉冲工作时间占比越大,烧蚀厚度越大。炭化层厚度在24 s左右达到最大值。

In order to study the ablation heat protection onⅠpulse combustor wall in dual-pulse solid rocket motor,a heat transfer and ablation model with variable thermal properties of the combination of Aramid/EPDM based on the pyrolysis kinetics and thermochemical ablation theory was established.Combined with thermal load environment distribution characteristics of theⅠpulse combustor insulator during the working process,the heat transfer and ablation research of theⅠpulse insulation material integrated with steel shell was carried out.Some affecting factors on the ablation results are analyzed,including the different pulse interval time and different pulse working time.The results show that the surface temperature of the thermal insulation material rises rapidly at the initial stage of the heat flow,but the temperature rise rate and the growth rate of the carbonized layer decrease with energy diffusion.When theⅡpulse is working,the serious ablation area of theⅠpulse insulation layer corresponds to the maximum value area of the airflow shear force.Without considering the overall peeling of carbonized layer,the longer the pulse interval time is,the smaller the ablation thickness of theⅠpulse insulation layer is,but the higher the shell temperature ofⅠpulse combustion chamber is,the easier it is to affect the structural integrity of the motor.The longer pulse duration,the smaller ablation thickness increase rate.When the working time of dual pulse motor is fixed,the larger the proportion ofⅡpulse working time,the greater the ablation thickness.The thickness of the carbonized layer reaches the maximum at about 24 s.