论文标题:水电站尾水系统数值模拟及试验研究
Experimental Study and Numerical Simulation Analysis on TailwaterSystem of Hydropower Station
论文作者 郑双凌
论文导师 马吉明,论文学位 硕士,论文专业 水利工程
论文单位 清华大学,点击次数 935,论文页数 94页File Size1494k
2004-05-01论文网 http://www.lw23.com/lunwen_70182/ 尾水系统;过渡过程;脉动压力;尾水调压室;变顶高尾水洞;明满流
tail system; transients; pressure fluctuations; tail surge tank; tail tunnel with slopping ceiling; free surface-pressurized flows
随着地下工程技术的不断发展,越来越多的水电站采用了地下厂房方案。而在采用首部式开发时,长尾水隧洞是地下厂房枢纽中不可缺少的组成部分。对于尾水系统,单管单机的布置方式比较成熟,尾水岔管的布置方式目前在大型电站中用的较多,如小浪底、向家坝、百色等,因而研究其在有尾水调压井和无尾水调压井的情况下的过渡过程,很有实用意义。根据各电站的实际情况,可以利用变顶高尾水洞代替尾水调压室,随着下游水位变化和电站负荷变化,尾水主洞中有可能产生明满交替水流的情况,这也是工程中十分关心的问题之一。有压非恒定流和明渠非恒定流的基本方程是水电站水力过渡过程的基本理论。本文对有压和明渠非恒定流的基本方程及尾水调压室的相关内容作了介绍和总结。对常用的特征线法进行了适当改进,用FORTRAN编写了适于多机共用一室一洞的长尾水系统的电算程序,可计算水锤变化、机组转速变化及调压室水位波动等,研究了水电站多机共用一室一洞的尾水系统水力动态特性。本文基于百色水利枢纽的模型试验,通过不同工况下尾水管处脉动压力的测量,对尾水管脉动压力进行了研究,对于作为水轮机能量恢复装置的尾水管,还比较了两种不同设计方案的优劣。对于多机共用一室一洞的长尾水系统,其规模巨大,技术难度高,水流性态的优劣直接关系到发电效益的大小和工程的安全可靠性,对设计方案的选择起着关键作用。本文通过模型试验,对多种工况的过渡过程进行了试验,并把试验与计算结果进行了比较。文章最后对变顶高尾水洞进行了介绍,总结了明满交替流的水力特征,介绍了明满流常用数值分析方法,以百色水利枢纽工程为例,进行了模型试验和初步分析,指出了产生明满流的临界尾水位。
With the development of underground engineering technology, now more and more hydropower stations are built under ground. If the headrace scheme is used, the long tailrace tunnel will be essential in underground project. Nowadays the single tube and single-unit hydroelectric station have been used widely and skillfully, but it is necessary for some large hydropower stations to use tailrace bifurcated tubes, just as Xiaolangdi, Xiangjiaba, Baishe project and so on. So it is significant to study the transients of long tailrace tunnel with tank or without tank. Some studies have shown that, tail tunnel with slopping ceiling structure can replace the tail surge tank and satisfy the stability requirement of turbine units. Because of the change of tail water level and power-station load, free surface-pressurized flows perhaps take place in main tailrace tunnel, which is one of the concerned problems in engineering.The elementary equations of pressure and open-channel unsteady flow are the essential theory of hydraulic transients of hydropower station. This article has introduced the equations and has summarized the knowledge of tail tank. By the characteristics method that has been properly modified, the program of long tail system has been compiled by FORTRAN to calculate its water hammer, rising ratio of rotational speed of generator and water lever fluctuation of tail rank. It studies the hydraulic dynamic characteristics of long tail system.Through the hydraulic model experiment of Baishe project, the article also studies the flow characteristics in draft tubes. Furthermore two different designs of draft tube are compared and analyzed.For the long tail system with several turbines, one tank and single main tunnel, which has large scale and difficult technology, its flow pattern affects the power benefit and safety reliability of engineering and also influences the design scheme. Through hydraulic transient test, the article compares the experimental result and calculated result.Lastly, the article studies the tail tunnel with slopping ceiling, summarizes the hydraulic characteristics of free surface-pressurized flows, and introduces its numerical analysis in common use. Through model test of Baishe project and primary analysis, the article indicates the critical tail water level that free surface-pressurized flows will take place in main tailrace tunnel.
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