模拟过载条件下EPDM绝热层烧蚀实验

Experiment on ablation of EPDM insulator simulating overload condition

关键词:  固体火箭发动机  绝热层  三元乙丙  粒子  烧蚀

Key words:  Solid rocket motor (SRM)  Insulator  EPDM  Particles  Ablation

摘要:

用一种粒子浓度、速度和角度可调的高过载模拟烧蚀发动机,开展过载条件下粒子冲刷对EPDM绝热层烧蚀特性影响的实验研究。实验结果表明:(1)存在一个临界速度,当冲刷速度低于临界速度时,粒子浓度,速度和角度对炭化烧蚀率影响较小,而当冲刷速度高于临界速度时,炭化烧蚀率随速度的增加而急剧增加,角度影响也较大。(2)弱冲刷条件下的炭化层表面平整,而粒子沉积条件下的炭化层表面附着有很多大粒径的粒子,炭化层结构也更加疏松,而强冲刷条件下,粒子由于速度较高而不易在炭化层表面沉积。(3)当低于临界速度冲刷时,炭化层的孔隙结构分布不均匀,存在致密/疏松分层结构,而高于临界速度冲刷时,炭化层结构则更为致密。(4)通过多元回归得到了炭化烧蚀率与粒子冲刷速度,浓度和角度的经验关系式。

Abstract:

Based on ablation experimental motor which can regulate the values of particle concentration,particle impact velocity and particle impact angle,experimental investigation has been conducted on the ablation of EPDM insulator under particles erosion and overload condition.The results show that:(1) A threshold velocity of the impacting particles exists.When the impacting velocity is below the threshold value,the influence of particle concentration,particle impact velocity and particle impact angle on charring ablation rate is small.But when above it,charring ablation rate increases rapidly as the increase of impacting velocity and particle impact angle also plays a very important role as well.(2) The surfaces of charring layer are flat during the weak impacting conditions,while lots of large size particles are attached to the surface of charring layer and the structures are looser than others in particle deposition conditions.During the conditions of severe impacting,particles could not stay on the surface of the charring layer due to their high velocities.(3) A compact/loose structure exists in the charring layer when the impacting velocities are above the threshold value.While an integral impact structure is found when the impacting velocities are under the threshold value.(4) The empirical formulas,accounting for the relationship between charring ablation rate and particle erosion conditions including particle velocity,particle concentration and particle impact angle,are obtained by multiple regression.