不可逆变化

As the complete characteristic curves of reversible pump turbine are often used to calculate the instantaneous parameters, this paper studies the characteristic curve and the wicket closure and opening law in pumped storage plants.Chapter 1 presents the importance and the necessity of this study and reviews the previous related research on hydraulic transient process and valve regulation in pumped storage plants.Chapter 2 analyzes the six collected characteristic curves of reversible pumped turbine and studies their diversification from the point of view of specific speed. The six collected discharge and moment curves with maximum efficiency have been fitted to piecewise continuous curves. This curve-fitting procedure is listed.Chapter 3 takes Liyang Pumped storage plant as an example and analyzes the effect of different characteristic curves on regulation guarantee parameters and the variety of its trochoid during the same operation status.Chapter 4 takes three pumped storage plants with different heads as examples and studies the characteristic of coordinated closure with wicket gate and ball valve and its effect on dynamic pressure in the spiral case, inlet pressure in the draft tube and the rise of rotating speed.Chapter 5 summarizes this paper and point out what should be done in the future research.

由于在过渡过程分析计算中，需要频繁利用可逆式机组的全特性曲线推求机组的瞬时参数，所以本文就特性曲线及关闭规律问题进行了研究，其主要内容如下：第1章，指出本文研究的意义和目的，回顾前人对水力过渡过程、抽水蓄能电站及阀调节的研究成果，在此基础上提出本文的研究内容；第2章，针对收集到的六套特性曲线，从比转速的角度出发来研究可逆式机组特性曲线的变化规律；并对六套曲线的最高效率流量和力矩曲线进行分段拟合，得到各分段函数的具体形式，再通过举例说明最高效率曲线的拟合步骤；第3章，以溧阳抽水蓄能电站为实例，分析讨论不同比转速特性曲线对调保参数造成的影响及对于相同工况其轨迹线的变化；第4章，结合高、中、低三水头段抽水蓄能电站，在导叶直线关闭的基础上，研究导叶与球阀协联关闭规律的特点及对蜗壳动水压力、尾水管进口压力及转速上升造成的影响；第5章，总结全文，提出今后研究的重点和方向。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。