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一、前言众所周知空放阀可以减少水电站压力引水系统中的流速变化率,在调速器和导水机构协同作用之下,保证水压力上升和机组转速上升都限制在允许的范围之内。关于空放阀的特性和选择计算,在水电站设计手册和水电站设备等有关书上都有阐述。但是对于空放阀正常运行时压力引水系统中的水锤压力计算公式(以下简称“基本公式”)却没有直接给出来。特别是以往对于基本公式的求解采用“试算法”,需要进行几次试算才能得到比较满意的近似值。本文试图对基本公式进行推导和求出它的“求解表达式”。在教学实践中,通过对某水电站进行毕业设计,在计算空放阀水锤压力时采用此基本公式和求解表达式,简便易行,大大地提高计算效率,收到明显的效果。在实际工程中很有实用价值。
I. Preface It is well-known that empty relief valves can reduce the rate of change of the flow rate in the pressure diversion system of a hydropower station. Under the synergetic effect of the governor and the guide mechanism, the increase of water pressure and the increase of unit speed are limited within the allowable range. On the air valve characteristics and choice of calculation, in the hydropower station design manuals and hydropower station equipment and other related books have elaborated. However, the calculation formula of water hammer pressure (hereinafter referred to as “basic formula”) in the pressure diversion system during the normal operation of the empty release valve is not directly given. In particular, the “trial method” was used to solve the basic formulas in the past, and several trial calculations were required to obtain satisfactory approximations. This article attempts to deduce the basic formula and find its “solution expression.” In teaching practice, through the graduation project design of a certain hydropower station, this basic formula and solution expression are used in the calculation of water hammer pressure of empty discharge valve, which is simple and easy to operate, greatly improves the calculation efficiency and receives obvious effect. In the actual project is very practical value.