Experimental Study Of Insulation Ablation Eroded By High-Temperature And Dense Two-Phase Flow

High acceleration and complex grain can both cause particles to aggregate highly in local part of SRM, thus form high-temperature and dense two-phase flow. The dense two-phase flow has a considerable effect on combustion, thermo-structure and internal flow field of SRM, especially worsening ablation of insulation. Such is the problem that required to be settled urgently in SRM investigation. The paper presented the investigation on insulation ablation eroded by high-temperature and dense two-phase flow. Particle properties in different aggregation states and chamber pressure were researched; the influences of aggregation state, pressure and resident time on particle size distribution were also discussed. The erosion experiments of multi-layer composite material with different particle concentration, impact velocity and angle were carried out, and the ablation mechanism of insulation under low velocity impact condition was analyzed. Using RTR(Real-Time Radiography) technique, the measurement of dynamic insulation ablation process eroded by high-temperature and dense two-phase flow was developed.Results can be summarized into three parts:1) The results of particle size analysis in high-temperature and dense two-phase flow showed that particle size distribution in aggregation state is much bigger and wider than that in general state. With the increasing of aggregation, particle size increases, as well as the proportion of big particles rises. Particle size increases with pressure especially in higher-pressure range. The resident time varies with aggregation state; long resident time would result in big size particles increment when aggregation is heavy. Particle composition analysis indicated that the main content was (X-AI2O3, which increases with pressure. When pressure is low and resident time is short, Al can be checked out.2) Within the low velocity impact range of high-temperature and dense two-phase flow, the impact velocity of particles is the main influence factor on erosion of insulation, while the contribution of particle concentration is relatively small. An empirical relation between thickness of char layer and sate parameters of particles was established based on experiments. Using charring ablation code, erosion rate in high-temperature and dense two-phase flow conditions can be indicated.3) An experimental method of dynamic erosion of insulation was developed with RTR technique. Dynamic regression behavior of insulation was captured in the experiment, which proved that the experimental method adopted was valid. Instantaneous and meanerosion rate versus time were achieved by image processing.