非同步导叶对混流式水泵水轮机“S”特性影响研究

发布时间：2018-04-02 10:40

本文选题：水泵水轮机　切入点：非同步导叶　出处：《兰州理工大学》2014年硕士论文

【摘要】：随着经济建设的快速发展及工业用电需求的不断增大,抽水蓄能机组作为目前可以商用的大型储能设备,具有水电设备启停快速和调节灵活等优点,能有效地应付负荷的变化,起到优化电源结构,确保电网安全,提高总体经济效益等作用。目前抽水蓄能电站的高速建设与发展已势在必行,国内大型抽水蓄能电站的建设亦已相继开工。然而作为抽水蓄能电站核心设备的水泵水轮机,其运行工况复杂多变,作为水泵水轮机瞬态过渡过程中最重要的环节,其水轮机启动工况下的“S”特性严重影响了水泵水轮机运行的安全性及稳定性,致使机组在水轮机工况低水头启动并网时发生困难等。目前改善水泵水轮机“S”特性最为成熟可靠的方法就是采用导叶非同步(预)开启方式。但导叶不同步动作在水泵水轮机开启方式中的应用却为水泵水轮机的研究带来了新的水力学问题。因此,通过开展非同步导叶装置的投入对水泵水轮机“S”特性的改善及其对机组内流特性影响的研究,对深入了解水泵水轮机“S”特性内流诱导机理、提高水泵水轮机机组运行稳定性具有重要意义。据此,本文以国内某抽水蓄能电站水泵水轮机机组的模型机为研究对象,建立三维数学模型,进行模型机组水轮机工况下的数值模拟,分析探讨投入非同步导叶装置后,非同步导叶不同导叶对数、不同导叶布置位置以及导叶不同开启角度情况下的机组内部流动特性和外特性,并得出以下结论： (1)通过对比分析未装设非同步导叶水轮机启动工况下机组转轮域内部流动特征可知,机组在小流量工况运行时,水流方向与转轮叶片进口存在很大的冲角,在活动导叶与转轮进口之间以及转轮进口处形成了大量的漩涡,几乎阻塞流道,这即是机组“S”特性产生的重要原因之一。 (2)非同步导叶装置的投入可以改善水泵水轮机组的“S”特性。各非同步导叶布置方案下机组外特性分析结果表明：同一开启位置、同一预开导叶数目时,预开角度越大特性曲线改善越明显；非同步导叶数目为两对以上(包括两对)时,分散布置优于集中布置,而对于一对预开导叶工况则是7#-17#位布置优于2#-12#位布置,即非同步导叶的布置应尽量避开鼻端位置；并非预开导叶数目越多机组“S”特性改善效果越好,相反当预开导叶数目增加到三对时其改善效果反而下降,预开两对非同步导叶改善效果最好。 (3)各非同步导叶布置方案下机组内特性分析结果表明：非同步导叶的投入强制增大了过流量,减小了进口冲角,减弱了转轮进口以及转轮叶片之间的漩涡,改善了水泵水轮机“S”特性。但非同步导叶的投入同时也扰乱了蜗壳内部的流动状态,破坏了原转轮内部的漩涡对称结构,影响了转轮的受力分布,使得转轮所受的水流冲击力不等,进而影响机组的运行稳定性 (4)综合对比各工况下的数值分析结果,得到该机组最优非同步导叶布置方式为预开两对非同步导叶、预开导叶对称布置(对应包角值分别为333.18。、243.180、153.18°、63.18。)且预开角度为30°。
[Abstract]:With the increasing demand for the rapid development of industrial economy and the construction of pumped storage units, large storage as the commercial equipment, with hydropower equipment start and stop fast and flexible adjustment and other advantages, can effectively cope with the change of load, to optimize the power structure, ensure the safety of power grid, improve the overall economic benefits at present. The construction and development of high speed pumping station has been imperative storage, large domestic power plant construction has been started pumping energy storage.
However, as a pumped storage pump turbine core equipment of power plants, the complex operating conditions, as the most important transient pump turbine transition process, the water turbine startup mode of "S" characteristics have a serious impact on the pump turbine operation safety and stability, resulting in difficulties in the turbine unit low head start when the network condition. The improvement of S character of pump turbine is the most mature and reliable method is to use the contraprop synchronous (pre) open the way. But the guide vane is not synchronized movements in the open application mode of the pump turbine is of pump turbine has brought new problems. Therefore, hydraulics the research, carried out by nonsynchronous guide vane device input to the S character of pump turbine and its influence on the improvement of flow characteristics within the unit, to understand the S character of pump turbine internal flow induced The guiding mechanism is of great significance to improve the operating stability of the pump turbine unit.
Accordingly, this paper uses a domestic pumped storage power plant model machine pump turbine as the research object, establish three-dimensional mathematical model, numerical simulation of the turbine model under the condition of unit, analysis of the input of nonsynchronous guide vane device, nonsynchronous guide vane of different guide vanes number, location and different guide vane guide vane the flow characteristics of internal and external characteristics of unit under different opening angle, and draw the following conclusions:
(1) through the contrast analysis did not install the nonsynchronous guide vane of turbine start-up flow features internal runner domain conditions set at low flow rates, the flow direction and the blades are very import angle between the guide vane and runner, and imported wheel inlet in the activities of the formation of a large number of vortex this is, almost blocking flow, is one of the important causes of unit "S" characteristics.
(2) non synchronous input device can improve the vane pump turbine units of the "S" characteristics. The nonsynchronous guide vane arrangement under the unit characteristic analysis results showed that the same open position, with a number of pre opening guide vanes, preopen larger angle curve improvement is more obvious; nonsynchronous guide vane the number of more than two (including two pairs), distributed better than the centralized arrangement, and is better than 2#-12# 7#-17# layout layout for a pre condition that enlighten leaves, nonsynchronous guide vane arrangement should try to avoid the nose position; the number of leaves is not pre channel unit "S" characteristics of better effect on the contrary, when the number of pre leaves increased to three when the channel effect decreased to two preopen nonsynchronous guide vane effect is best.
(3) the nonsynchronous guide vane arrangement under unit characteristic analysis results show that the nonsynchronous guide vane increases the input of forced flow, reduce the inlet incidence angle, weakened between imports and runner blade vortex, improves the S character of pump turbine. But the same step guide vane input but also disrupt the flow state inside the volute, destroys the symmetry structure of the original vortex runner, affect the stress distribution of the wheel, so that the water flow impact by the runner range, thereby affecting the operation stability of the
(4) comprehensive comparison of numerical analysis results under different working conditions shows that the optimal asynchronous guide vane arrangement of the unit is to open two pairs of asynchronous guide vane, and the prearranged guide vane is symmetrically arranged (the corresponding angle values are 333.18., 243.180153.18 degrees, 63.18.), and the preopening angle is 30 degrees.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK730

【参考文献】