水泵水轮机“S”形区内流特性研究

发布时间：2018-06-25 11:56

本文选题：水泵水轮机 + “S”特性　；参考：《武汉大学》2017年硕士论文

【摘要】：在经济飞速发展的今天,无论是工业用电还是居民生活用电的需求量都在不断增大,不同时段用户用电量的巨大差异要求电网扩大规模的同时具有更大、更灵活的调节能力。而具有削峰填谷功能的抽水蓄能电站是实现这一目标的有效手段。但由于水泵水轮机全特性曲线中存在一个不稳定的"S'"特性区,常会造成机组的启动并网困难以及空载的不稳定,产生巨大的经济损失。为了解决这个不稳定区带来的严重影响,有必要采取方法对"S"区的特点展开研究。本论文基于计算流体力学方法,研究水泵水轮机在定常和非定常下的流动状态和压力脉动情况,分析"S"形区流动特性。主要研究内容如下:1对水泵水轮机在水轮机工况、飞逸工况和制动工况下进行定常计算。分析各个过流部件在这三种工况下的内部流场状态,探讨不同导叶开度对导叶区以及转轮区中流场的影响,同时分析不同工况下转轮叶片的荷载情况。结果表明,导叶开度改变水泵水轮机的过流量和转轮进口冲角,对转轮内部流动有重要影响;水轮机工况下,叶片受正向力矩;飞逸工况下,叶片的头部和尾部受负向力矩,叶片中部受正向力矩;制动工况下,叶片头部和尾部都受负向力矩,叶片中部受到力矩为0。2对水泵水轮机在水轮机工况、飞逸工况以及制动工况下进行非定常数值计算。分析各过流部件内的流场随时间的变化情况,水泵水轮机在水轮机工况、飞逸工况和制动工况下各区域的能量特性,以及各个过流部件的压力脉动变化规律。结果表明,无叶区和转轮区在飞逸工况下会形成与转轮旋转方向相同、转速为转轮转速的0.5倍和0.6倍的旋涡;在飞逸工况和制动工况下尾水管直锥段中生成沿管壁与转轮旋转方向相同、转速为转轮转速的0.55倍和0.85倍的涡带;设计工况(水轮机工况)与非设计工况(飞逸工况和制动工况)在能量特性上的主要差异在活动导叶区域;压力脉动分析表明蜗壳中压力脉动与尾水管中的低频压力脉动相关,导叶区内的压力脉动受动静干涉的影响较大。对转轮轴向受力的分析表明,飞逸工况下的轴向水推力会出现高频率的振荡,制动工况下的轴向受力倾向于抬机方向。
[Abstract]:With the rapid development of economy, the demand for both industrial and residential electricity consumption is increasing. The huge difference of power consumption in different periods requires the power grid to expand its scale and have a larger and more flexible regulating capacity. The pumped-storage power station with peak cutting and valley filling function is an effective means to achieve this goal. However, due to the existence of an unstable "S'" characteristic area in the full characteristic curve of the pump turbine, it will often lead to the difficulty of starting and connecting the grid of the unit and the instability of the no-load, resulting in huge economic losses. In order to solve the serious influence of this unstable region, it is necessary to study the characteristics of "S" region. Based on the computational fluid dynamics (CFD) method, the flow state and pressure fluctuation of a pump turbine under steady and unsteady conditions are studied, and the flow characteristics in the "S" shape region are analyzed. The main research contents are as follows: 1. The steady calculation of pump turbine under turbine condition, flight escape condition and braking condition is carried out. This paper analyzes the internal flow field state of each overflowing component under these three conditions, discusses the influence of different guide vane opening on the flow field in the guide vane region and the runner zone, and analyzes the load situation of the runner blade under different working conditions. The results show that the overflow rate of the pump turbine and the inlet angle of the runner are changed by the guide vane opening, which has an important effect on the internal flow of the runner, the blade is subjected to positive torque under the turbine working condition, and the head and tail of the blade are subjected to the negative torque under the flight escape condition. Under the braking condition, the head and tail of the blade are both subjected to negative torque, and the moment to the middle of the blade is 0.2 for the unsteady numerical calculation of the pump turbine under turbine, runaway and braking conditions. This paper analyzes the variation of flow field with time, the energy characteristics of each region under turbine, flight escape and braking conditions, and the variation law of pressure pulsation. The results show that the vortex formed in the leafless region and the runner region is the same as the rotation direction of the runner under the flight condition, and the rotational speed is 0.5 times and 0.6 times of the rotary speed of the runner. A vortex band is formed in the straight cone section of the draft tube under flight escape and braking conditions with the same rotating direction along the tube wall and the runner, and the rotational speed is 0.55 times and 0.85 times of the rotary speed of the runner. The main differences in energy characteristics between design (turbine) and off-design (flight escape and braking) conditions are in the active guide vane region, and pressure fluctuation analysis shows that pressure pulsation in volute is related to low frequency pressure fluctuation in draft tube. The pressure pulsation in the guide vane area is greatly affected by the dynamic and static interference. The analysis of axial force on the runner shows that the axial water thrust will oscillate at high frequency under flight escape condition, and the axial force under braking condition tends to lift machine direction.
【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV734.1

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