The Experimental Simulation Technique Of Flow Field Under High Acceleration Condition

It is important to develop experiment techniques to simulate flow field in the study of Solid Rocket Motor with high acceleration. By analyzing the characteristic of the flow field in overloading SRM and comparing several existing experiment techniques, a convergence-fold tube facility was developed. The flow field in chamber of SRM with high acceleration was simulated. Some inhibitor ablation experiments were carried out in this test facility. In order to explore the influence of particle diameter on flow field and ablation, particle collection experiments under simulated acceleration conditions were conducted and diameter distribution was obtained. The experiment results provided a basis for establishing inhibitor ablation model and thermal protection design.The work of this paper can be summarized into four parts:1. By analyzing the characteristic of the flow field of SRM under high acceleration condition, the following phenomena were discovered: particles were deflected and concentrated in local region by overloading, which reinforced inhibitor ablation, and the particle distribution alone the wall was affected by several factors. Focused on the relationship between ablation and its influence ingredients, this paper analyzed simulation techniques of flow field under high acceleration condition. Spinning test stand is difficult to simulate the flow field of SRM under high acceleration condition because of its Coriolis acceleration. The paper applyed principle analysis and numerical computation to compare the scheme of particle injection syphon and convergence-turn tube. The last method was adopted to conduct research because it could produce high concentrated particles stream and operated conveniently.2. Ablation experiments of six kinds of inhibitor were carried out in this convergent-fold tube facility. The average ablation rate of test specimens was greater than normal. Experimental result proved that the test facility could produce high concentrated particles stream. An improved test facility, which possessed more adaptability, was used to simulate the ablation state of SRM with high acceleration. The conclusion obtained from experimental result showed that particle concentrationis an important factor on inhibitor ablation.3. The numerical result indicated that particle distribution alone surface of inhibitor was enslaved to particle diameter. Particle concentration changed from single-peak distribution to multi-peak distribution according to particle size increase. The particle collection facility was developed based on the rule of particle colliding and congregating in high acceleration SRM. The coagulate pattern of particle was gained through Electron Microscope scanning. Percentage distribution of particle numbers and mass according to particle diameters was obtained. The results were modified considering temperature variation. Compared the measure result of laser holographic in normal motor offered from reference with experimental result, the conclusion was achieved: particle size under high acceleration condition was greater than normal.4. By observing the macrocosmic and microcosmic state of the test specimens, the ablation pattern of inhibitor was put forward and ablation mechanism was analyzed. The critical average particle diameter that influenced inhibitor ablation was obtained. The time-dependent ablation expression associated particle concentration and angle was achieved through analyzing their variation alone with the change of specimen figure. By investigating the specialty of functions in the expression, the following conclusion was drawn: particle concentration was the dominant factor that enforced ablation, and angle contributed to ablation via cutting the char layer.In summary, this paper developed experiment techniques to simulated flow field in overloading SRM. It is an effective way to study inhibitor ablation pattern under high acceleration condition. The experiment results provided basis for investigating ablation mechanism and thermal protection...