【作者】 刘洋；

【导师】 何国强；

【作者基本信息】 西北工业大学 ， 航空宇航推进理论与工程， 2004， 硕士

【摘要】 本文以高过载固体火箭发动机研制需求为背景，围绕高过载发动机内流场的地面模拟试验技术展开研究。通过分析过载条件下流场的特点，提出并比较了现有过载地面模拟试验技术的优缺点，最终确定了收敛—折管的模拟试验方法，模拟了高过载条件下发动机燃烧室内的高浓度粒子流，利用该方法开展了高过载模拟冲刷条件下的绝热层烧蚀特性研究及绝热层抗冲刷能力的筛选试验。为分析粒径对流动计算、烧蚀的影响，开展了模拟过载条件下的粒子收集试验，获得了在聚集状态下的粒径分布。最后对高过载条件下绝热层烧蚀的影响因素作了详细的分析。本文的研究工作概括为以下四部分： (1)通过分析固体发动机在高过载作用下的流场特点，发现流场中凝相粒子在过载作用下发生偏转，并在局部大量聚集而形成稠密的粒子流，强化了对绝热层的烧蚀；粒子在发动机壁面上的聚集分布受多种因素影响。针对高过载问题中绝热材料烧蚀的影响因素，进行了地面模拟高过载发动机流场的方案分析。理论分析证明旋转试车台不能克服科氏加速度的影响，难以用来开展高过载条件下发动机流场的地面模拟试验。本文应用原理分析、数值计算等手段，对粒子加入、弯管和收敛—折管方案进行了比较，认为收敛—折管方案可以产生发动机在飞行过载中的凝相粒子聚集效应，且烧蚀参数控制方便。 (2)通过开展收敛—折管试验装置下的绝热层抗冲蚀能力筛选试验，获得了该条件下六种不同绝热材料及工艺的平均烧蚀率，发现粒子冲刷条件下的烧蚀率要比常规下的烧蚀率大得多，进一步证明了收敛—折管试验装置具有产生高密度粒子流的能力；发展了一套烧蚀参数范围更宽的高过载流场模拟试验装置，并进行了绝热层烧蚀试验。试验结果表明：粒子聚集浓度是绝热层烧蚀的重要影响因素。 (3)数值计算表明两相流中粒径对绝热层表面粒子浓度分布有很大的影响，且随着粒径的增大粒子浓度由单峰分布变为多峰分布。针对过载条件下发动机流场中粒子相互碰撞和聚集的规律，研制了一种能对聚集后的粒子状态进行冻结的收集试验装置。通过粒子收集试验和对收集到的粒子进行电镜观察，分析了粒子的聚集特点，获得了试验条件下的颗粒数分数和质量分数随颗粒直径的分布曲线，并针对温度因素进行了修正。通过与文献中非聚集状态粒径分布的测量结果相比较，证明聚集条件下颗粒的直径要比普通条件下颗粒直径大得多。 (4)通过对试验后绝热材料试件的表观和微观状态分析，提出了过载条件下绝热层的烧蚀模式，并分析了其烧蚀机理，获得了试验条件下影响绝热层烧蚀的平均颗粒直径。通过分析烧蚀过程中粒子浓度、角度等随试件型面的变化规律，结合试验结果进行了回归计算，得到了颗粒浓度、角度等为主要影响因素的烧蚀量随时间变化的关联式:利用此式获得了试件型面随时间变化的规律。通过分析关联式中各项函数特性，得到粒子聚集浓度是影响烧蚀量的主要因素，而角度对于烧蚀量的贡献主要体现在对绝热层炭层的剪切破坏上的结论。 通过本文的研究工作，发展了一种高过载发动机内流场模拟实验技术，为开展高过载条件下绝热层烧蚀研究提供了有效的实验手段;获得的绝热层烧蚀实验结果以及粒径分布规律，为高过载条件下绝热层机理研究奠定了基础，为高过载发动机热防护设计提供了依据。更多还原

【Abstract】 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更多还原