气垫调压室临界稳定断面计算参数取值讨论

针对气垫调压室断面尺寸通常取决于其临界稳定断面这一特点,指出电站静水头、机组引用流量和调压室水位微幅扰动时气体的热力学过程是影响该临界稳定断面的重要因素。对调压室内气体与环境之间热传导过程进行研究,认为以等温变化(多方指数取1.0)模拟小扰动下气体的热力学过程更符合实际情况。对气垫调压室临界稳定断面计算公式进行数学分析并结合工程实例进行计算,结果表明,以电站正常运行时可能出现的最大静水头及其对应流量作为临界稳定断面的计算条件,能满足其他可能工况下的调压室水位波动稳定性要求,更利于工程安全。

Selection of parameters for calculating critical stability cross-sectional area of air-cushion surge chambers

The cross-sectional size of an air-cushion surge chamber is usually determined by the critical stability cross-sectional area, and the hydrostatic head, the flow through the generating set, and the thermodynamic process of gas in a surge chamber when there is little perturbation of the water level are three main factors affecting the critical area. Investigations of the heat conduction process between the gas in the surge chamber and the surroundings show that the isothermal change (with a polytropic exponent of 1.0) is most appropriate for simulating the actual conditions when there is little perturbation. Through mathematical analysis of a formula regarding the critical area and a case study, it is concluded that using the maximum hydrostatic head during the normal operation of a hydropower station and the corresponding flow as the calculation conditions can satisfy the fluctuation stability requirement of the water level in the surge chamber of other operation schemes , which would facilitate the safety of projects.