长时间小过载条件下发动机流场特征及绝热层烧蚀分析

Flow Field and Ablation Mode Analysis of Insulator under Low Acceleration with Long Operation Time Conditions for Solid Rocket Motor

关键词:  固体火箭发动机  绝热层  烧蚀  高过载 

Key words:  Solid propellant rocket motor (SRM)  Insulator  Ablation  High acceleration

摘要:

以揭示固体火箭发动机在飞行条件下绝热层的异常烧蚀特性为目的,针对小过载、长作用时间条件下大长径比流道的发动机开展了三维两相流场的数值模拟研究,详细分析了发动机内流道内不同区域的颗粒聚集特征,并结合发动机失效部位处绝热层的烧蚀形貌进行了失效模式分析,针对性地提出了改进措施。研究结果表明:(1)不同过载条件下发动机内颗粒聚集和分布状态受过载大小和发动机流道结构共同作用且影响规律复杂,所引起的绝热层异常烧蚀模式和机理不同,特别是小过载长作用时间条件下的异常烧蚀需要引起设计者重视。(2)颗粒聚集在绝热层表面的换热或冲蚀都将引起绝热层局部烧蚀加剧,形成的“凹坑或凹槽”烧蚀形貌会造成颗粒的二次聚集效应,进而加剧烧蚀过程。(3)通过增加发动机旋转动作和局部绝热层加厚,可以提高发动机的飞行安全性。 

Abstract:

Focusing on the abnormal ablation of insulator of the solid rocket motor under flight condition, the three-dimensional two phase numerical simulation of a certain larger long diameter ratio tactical missile solid rocket motor under low acceleration-long duration condition was carried on. And the two phase flow characteristic of different area in the solid rocket motor flow path was analyzed. According to the ablation profiles of insulator and the detail of flow characteristic near the failure point, the insulator ablation characteristic and disabled mode were discussed and some improvment methods were brought forward. The results show that:(1) The particle concentration distribution and two phase flow characteristic in the solid rocket motor are decided by the acceleration direction and magnitude as well as geometry feature of flow path jointly. Then the ablation mechanism and failure mode are complicated and the abnormal ablation of insulator under low acceleration short duration condition must be considered. (2) The aggradation of particles on the insulator surface results in the forced heat transfer and particle erosion promotes ablation of insulator. And the groove and concave on the insulator surface resulting from particle erosion may focalize the particles and quicken the insulator ablation farther. (3) By making the solid rocket motor spinning or thickening the insulator locally, the flight safety can be improved. 