【摘要】 基于一种颗粒冲刷状态参数大范围可调的高过载地面模拟试验发动机,针对三元乙丙(EPDM)绝热材料开展了15次烧蚀实验,获得了颗粒冲刷状态参数和炭化烧蚀率之间的宏观影响规律,通过扫描电镜分析了炭化层结构的形貌特征,并以炭化层孔隙结构为纽带,剖析了颗粒冲刷条件下热化学烧蚀和颗粒侵蚀之间的耦合关系。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,颗粒浓度、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)不同的颗粒冲刷状态条件下,炭化层形貌结构差异较大,内部存在明显的"致密/疏松"结构;(3)根据颗粒冲刷参数和炭化层形貌关系,提出了3种典型的烧蚀冲刷状态,即弱冲刷状态、颗粒沉积状态及强冲刷状态;(4)分析了不同颗粒冲刷状态下的绝热层烧蚀过程,获得了热化学烧蚀和颗粒侵蚀之间的耦合关系。更多还原

【Abstract】 The influence of particle concentration,impacting speed and angle on ablation characteristic of EPDM insulator were investigated based on test facility which can adjust particle concentration,impacting speed and angle.Different ablation rates of insulator material were obtained under different state parameters of particle erosion.Structures of carbonization layers were analyzed by scanning electron microscopy.Base on the structure of cavity,insulator mechanism of EPDM under high acceleration condition was discussed.The results show as follows:(1) By analyzing the influence law of carbonized ablation rates affected by different particle concentrations,impacting velocities and angels,it is found that a critical speed exists.When impacting speed is below the critical value,carbonized ablation rate changes slowly with speed and angle respectively.But if exceeding it,concave pits appear on the surface of carbonized layers.Carbonized ablation rates rise up sharply and the effects of angels cannot be ignored.(2) There are huge discrepancies in the surface and cross section of insulation layer,erosion modes and destroy mechanisms of different particle erosion condition.Compact/loose structures was formed in carburization layer of EPDM insulator.(3) In observing the structures of carbonized layers of basic formula by scanning electron microscope,three typical surface morphologies of the ablation were discovered with the increase of particle erosion speed.(4) The coupling relationship between thermochemistry ablation and parcile erosion is established through analyzing the abalation process of EPDM insulator under different parcile erosion conditions.更多还原