气垫式调压室稳定断面积研究

Study on the stable cross-sectional area of air-cushion surge chambers

基于刚性水锤理论,考虑了压力管道的水流惯性及实际水轮机特性和调速器作用,运用稳定性理论,推导了气垫式调压室临界稳定断面积的详细公式。在此基础上分析最不利稳定断面积的取值,根据近年来国内十个不同水头段引水式水电站的资料,进行该公式各项参数的统计分析。结果表明:气垫式临界稳定断面详细公式主要由考虑水轮机特性的引水隧洞水流惯性项F_(th1)、压力管道项F_(th2)及调速器特性项F_(th3)三部分组成,在形式上与常规调压室一致,区别仅在于(1+m×p_0/l_0)倍的系数关系。气垫式调压室最不利稳定断面积取决于最大水头与设计水头之间的某个既能满足(1+m×p_0/l_0)较大,也能满足e>1的水头。随着电站设计水头的增大,系数(1+m×p_0/l_0)的值也呈线性增大趋势,不能笼统地判断气垫式调压室适用于高水头水电站,应根据电站的工程规模作进一步详细论证。

Based on the rigid water column theory and considering the water inertia of penstock and charac-teristics of turbine and governor, a detailed formula for critical stable cross-sectional area of air-cushionsurge chambers was derived. The parameter values in this formula calculated for the largest stable cross-sec-tional area were discussed in this paper. According to the data of ten different national diversion hydropow-er stations in recent years, the parameters in this detailed formula were statistically analyzed. The resultsshow that the detailed formula for air-cushion surge chambers is consists of three parts：one is correspond-ed to the diversion tunnel term of F（th1）,penstock term of F（th2） and governor term of F（th3）,which are formallyconsistent with the regular surge chamber,only except with the coefficient of（1＋m×p0/l0）. The largest sta-ble cross-sectional area is dependent on the water head between design and maximum head, which canmeet both a larger value of（1＋m×p0/l0） and e1. The value of（1＋m×p0/l0） linearly increases with the in-crease of design head. The application of air-cushion surge chambers should be further demonstrated in de-tails based on the scale of power plant engineering,rather than assumptions that it suit for any high-headhydropower stations.