跌坎型底流消能工冲击区底板荷载计算

发布时间：2018-04-14 17:00

本文选题：跌坎型底流消能工 + 时均压强　；参考：《昆明理工大学》2014年硕士论文

【摘要】：近年来,随着我国水利水电事业迅速发展,新建了许多大中型水利水电工程,这些工程往往具有高水头、单宽流量大的特点,泄洪消能问题较为突出。随着我国经济的发展和国民生产总值的提高,人们不再是仅仅停留在经济效益作为水利水电工程的评价标准,而是综合考虑水电项目对生态环境的影响。对生态环境要求较高的正在建设和即将建设的水电工程都放弃了挑流消能方案而选择底流消能。基于底流消能的跌坎型消能工是一种能适应低水头、单宽流量大的新型消能工。由于跌坎的存在,水流进入消力池后,沿程得到一定程度的扩散,主流两侧形成漩涡以及强烈的紊动剪切扩散,将高速的主流引离临底区域,临底流速有效降低,因此基于底流消能的跌坎型底流消能工,具有消能率高、入池流态稳定,对地质条件适应性强以及水流雾化小等优点,该消能工具有较好的应用前景。由于入射水流到达消力池底板时,在冲击区水流对底板形成冲击作用,临底流速、时均压强均达到峰值,对消力池底板冲刷破坏较为严重。并且冲击区是跌坎型底流消能工主要的消能区域,对冲击区的水力特性研究、底板荷载计算,有助于提高跌坎型底流消能工的使用寿命,对优化跌坎型底流消能工体型设计有着重要意义。本文是基于国家自然科学基金(项目编号：51169008)而立题,结合理论分析、水力学模型试验和数值计算的方法,研究了跌坎型底流消能工冲击区水力特性,总结出跌坎型底流消能工淹没射流区射流轴线最大速度衰减的半经验公式,总结出跌坎型底流消能工冲击区的时均动压的计算公式。
[Abstract]:In recent years, with the rapid development of water conservancy and hydropower industry in China, many large and medium-sized water conservancy and hydropower projects have been built. These projects often have the characteristics of high water head and large single wide discharge, and the problem of flood discharge and energy dissipation is more prominent.With the development of our country's economy and the increase of GDP, people are not only considering the economic benefits as the evaluation standard of water conservancy and hydropower projects, but also considering the impact of hydropower projects on the ecological environment.The hydropower projects which are under construction and are about to be constructed have given up the energy dissipation scheme with high ecological environment and opted for the energy dissipation at the bottom flow.Energy dissipation based on bottom flow is a new type of energy dissipator with low head and large flow rate.Because of the existence of the fall, the flow into the stilling pool, along the course to a certain extent of diffusion, the formation of vortex on both sides of the mainstream and strong turbulent shear diffusion, leading the high-speed mainstream away from the near bottom area, the near bottom velocity is effectively reduced,Therefore, the energy dissipation tool based on the bottom flow energy dissipation has the advantages of high energy dissipation rate, stable flow state in the pool, strong adaptability to geological conditions and small atomization of water flow, etc. The energy dissipation tool has a good prospect of application.When the incident water reaches the bottom of the stilling pool, the flow in the impact zone forms an impact on the bottom, and the velocity of flow near the bottom and the average pressure at the time all reach the peak value, and the scour damage to the bottom of the stilling pool is more serious.And the impact area is the main energy dissipation area for the energy dissipators. The study of hydraulic characteristics of the impact zone and the calculation of floor load will help to improve the service life of the floor flow dissipators.It is of great significance to optimize the design of energy dissipators.This paper is based on the National Natural Science Foundation of China (item No.: 51169008), combining with theoretical analysis, hydraulics model test and numerical calculation, the hydraulic characteristics of the impact zone of the energy dissipator with the type of floor flow are studied.The semi-empirical formula of maximum velocity attenuation of jet axis in submerged jet zone is summarized, and the calculating formula of time-averaged dynamic pressure in the impact zone of energy dissipator is summarized.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV653;TV31

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