含长连接管的调压室流量系数改进研究

Investigation on Improvement of Flow Coefficient of Surge Tank with Long Connecting Pipe

在水力过渡过程计算中,通常将含长连接管的调压室简化成常规阻抗式调压室,但当连接管长度较长时,常规阻抗式模型无法精确预测其涌波水位。因此,分析含长连接管调压室的水力特性及其与常规阻抗式调压室的流量系数差异,在阻抗式调压室模型基础上提出了改进流量系数的预测模型,并与真实的含长连接管调压室模型计算结果进行了对比,开展了连接管尺寸的敏感性研究。结果表明,采用常规阻抗式调压室模型模拟含长连接管调压室涌波水位极值时,因流入流量系数取值偏小(一般为0.6)、流出流量系数偏大(一般为0.8),涌浪极值均偏小;改进后的流量系数可计入长连接管的影响,基于阻抗式调压室改进流量系数模型能准确预测含长连接管调压室涌波水位极值。

In the calculation of the hydraulic transition process, the surge tank with long connecting pipes is usually simplified as a conventional impedance surge chamber, but when the length of the connecting pipe is long, the conventional throttled model cannot accurately predict water level. This paper analyzed the hydraulic characteristics of the surge tank with long connecting pipe and its difference with the flow coefficient of the conventional throttled surge tank. Based on the throttled surge tank model, an improved flow coefficient prediction model was proposed, which is compared with that of the conventional throttled surge tank. The calculation results of the real surge tank model with long connecting pipes were compared, and the sensitivity research of connecting pipe size was carried out. The results show that when the conventional throttled surge tank model is used to simulate the extreme value of the surge water level in the surge tank with long connecting pipe, the inflow flow coefficient is too small(generally 0.6) and the outflow flow coefficient is too large(generally 0.8). The extreme values are all small;The improved flow coefficient can take into account the influence of the long connecting pipe, and the model based on the improved flow coefficient of the throttled surge tank can accurately predict the surge water level extreme value of the surge tank with the long connecting pipe.