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水轮机的开度变化规律对水击压强影响很大,反应十分灵敏。本文主要从理论上探讨在相同的T_s值下,找出一种最优的关闭规律,使相对水击压强ζ值小于任何关闭规律下的最大相对水击压强ζ_(max)值,相应于这种最优关闭规律下的开度称之为最优开度,而在最优开度下发生的各相同号等值正水击称之为最优水击,其值小于一相水击值或末相水击值。文中提出最优水击及其最优开度的计算公式和推导、计算举例,时一相水击(高水头水电站)和极限水击(中低水头水电站)的分析计算。水击压强是设计水电站的压力水管和进行机组强度计算必须计入的一项主要动荷载在相同的T_s值下,采用最优开度可以减小水击压力,从而可以降低建筑物和机组之造价。初步研究表明,对水头200米以上的高水头水电站来说,采用最优水击计算法更具有明显的经济价值。当然,采用最优开度后,相应地要求水轮机的调速设备必需具有相当高精度的分两段不同等速的关闭装置。
Turbine opening changes have a great impact on the water pressure, the reaction is very sensitive. In this paper, we mainly study theoretically to find out an optimal closing law under the same T_s value, so that the relative water hammer pressure ζ value is less than the maximum relative water hammer pressure ζ max value under any closing law, corresponding to this Under the optimal closing law, the opening degree is called the optimal opening degree, and the same water hammer that occurs under the optimal opening degree is called the optimal water hammer whose value is smaller than the one-phase water hammer value Or the final phase water hammer value. In this paper, the calculation formula and derivation of the optimal water hammer and its optimal opening, the calculation example, the time-phase water hammer (high head water station) and the limit water hammer (medium-low water head station) are analyzed and calculated. Water hammer pressure is the design of hydropower station pressure pipe and crew strength calculation must be included in a major dynamic load at the same T_s value, the optimal opening can reduce the water hammer pressure, which can reduce the buildings and units Cost. Preliminary studies show that the optimal water hammer calculation method has obvious economic value for high head hydropower stations with a head of more than 200 meters. Of course, the use of optimal opening, the corresponding requirements of the turbine speed control equipment must have a very high precision in two different speeds of the closure device.