The velocity head and momentum exchange at the T-junction between the surge tank with a riser and the tail water tunnel of hydroelectric powerplants have been introduced by using the Gardel’s head-loss formula. The effects of the velocity head and momentum exchange on the critical sectional area of the downstream tank have been analyzed. With Thoma’s assumption, the critical stable sectional area of the downstream throttled surge tank is derived theoretically. The study shows that the velocity head has an unfavorable effect on water level stability in the downstream surge tank while the effect of the momentum exchange is positive. These two effects counteract. Thus, the critical sectional area of a downstream throttled surge tank is close to that of a corresponding simple surge tank. However, if the size and shape of a riser are optimized, the area of the downstream surge tank may be further reduced. It is also demonstrated that a downstream throttled surge tank can reduce electricity loss and easily meet the requirements of stability in large flow oscillations when compared to a simple downstream tank.

本文研究工程中某些索状柔系结构在任意铰节点荷栽作用下的稳定平衡形状和张力计算问题。利用虚功原理，导出了描述其稳定平衡形状的状态递推方程式并给出了数值解的迭代计算步骤。若干算例表明：利用本文介绍的理论和计算方法对求解这类问题具有计算精度高、收敛速度快、稳定性好和适应性强的优点，对本文讨论的问题，计算工作量要比有限元法少。

基于面向图形系统的水电站过渡过程程序，提出了新的编码原则。并对此编码原则的理论基础和处理方法予以了讨论。

The transient process in the conduits of hydropower stations is a very complicated dynamic procedure coupled with fluid, machines, electricity, and even structure. The current methods used to analyze them separately cannot satisfy the design and the operation requirement of those large underground stations with long conduits. So it is necessary to develop a global physical simulation for the power station transients. As an initial discuss, this article focuses on the introduction of model similarity, model scale and some results about great fluctuation, small fluctuation and hydraulic interference in transient flow experiments.