淹没条件下高压水射流的流场特性研究

发布时间：2018-11-27 15:24

【摘要】：长江上游水道具有较大的航运潜力巨大,但对其开发利用明显不足;目前国家在建设长江黄金水道的同时又在提倡对长江航道生态的保护,既要有航运开发、又要有生态保护,这就为航道整治建设增加了一定的难度。目前炸礁等施工方法会对施工水域的生态环境产生毁灭性的破坏,因而研发一种生态环保的清礁技术对于长江航道的生态环境的保护具有重要的意义。因此,本文提出采用高压磨料射流水下切割礁石的新方法,为研发该水射流切礁的方法,初期的一个关键点在于阐明流速的衰减规律、射流流场的水动力特性等等,因而本文从这几点出发得出的主要成果如下:(1)本文文归纳总结了水射流的水流结构特征、冲击特征以及射流拟序结构的研究现状,概述了高压水射流目前主要的研究方法及取得的一些研究成果。(2)本文系统论述了高压水射流数值模拟的基本原理,并对所建立的数学模型进行验证,结果表明数模成果准确可信,可用于后续的模拟研究中。(3)根据不同水深下数值模拟的流场比对分析,得出了不同水深情况下的径向与轴向流速分布规律,展示了不同水深下近场轴线流速加速过程以及射流初始长度,解决了浅水射流水深对冲击效率影响的问题。(4)通过对数值模拟结果的分析,初步阐明了受限条件下高压淹没水射流轴向与径向不同时刻、不同位置下的流速分布情况,简要说明了涡旋分布、流线运动情况以及轴向流场流速随时间变化的特性。(5)建立不同靶距下的二维平面冲击射流数学模型,阐明不同靶距下的轴线流速、压强分布特性,论述了靶距对冲蚀孔径及深度的影响。
[Abstract]:The waterway in the upper reaches of the Yangtze River has great shipping potential, but its exploitation and utilization are obviously insufficient. At present, the country is promoting the ecological protection of the Yangtze River waterway while constructing the golden waterway of the Yangtze River. It is necessary to have both shipping development and ecological protection, which has increased some difficulties for the construction of waterway regulation. At present, the construction methods such as reef blasting will destroy the ecological environment of the construction waters, so it is of great significance to develop an eco-environmental cleaning technology for the protection of the ecological environment of the Yangtze River waterway. Therefore, in this paper, a new method of cutting reef underwater by high pressure abrasive jet is put forward. In order to develop the method of cutting reef by water jet, a key point in the initial stage is to clarify the law of velocity attenuation, the hydrodynamic characteristics of jet flow field, and so on. Therefore, the main results obtained from these points are as follows: (1) this paper summarizes the characteristics of water flow structure, impingement characteristics and the research status of jet structure. The main research methods and achievements of high pressure water jet are summarized. (2) the basic principle of numerical simulation of high pressure water jet is discussed systematically, and the established mathematical model is verified. The results show that the numerical simulation results are accurate and reliable and can be used in subsequent simulation research. (3) according to the flow field comparison analysis of numerical simulation under different water depths, the radial and axial velocity distributions under different water depths are obtained. The acceleration process of near-field axis velocity and the initial length of jet under different water depths are demonstrated. The problem of the impact efficiency of shallow water jet water depth is solved. (4) the numerical simulation results are analyzed. The velocity distribution of high pressure submerged water jet at different positions and at different times in axial and radial direction under confined conditions is preliminarily explained, and the vortex distribution is briefly explained. (5) the mathematical model of two-dimensional plane impinging jet with different target distances is established, and the characteristics of axial velocity and pressure distribution under different target distances are illustrated. The effect of target distance on the diameter and depth of erosion is discussed.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U617

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