瞬变气液两相流在变顶高尾水系统中的应用

This project aims at the application of transient gas-liquid two-phase flow theory into the mechanical analysis and mathematical simulation of free surface- pressurized mixed flow in the system of tailrace tunnel with sloping ceiling, which is a new type of tailrace conduits in hydropower station. There are four main results: (1) The analog theory of physical model combined with hydraulic, mechanic and electric equipments for experiment has been studied. It provides the basis for the normal model test for the whole water delivery conduits system of tailrace tunnel with sloping ceiling equipped with turbo-generator units; (2) The movement of mixed flow interface under the condition of steady flow has been analyzed by applying interface stability theory of gas-liquid two-phase flow. It is not only that the internal mechanism, main influence factor and variety law of the mixed flow phenomena has been illustrated, but also the calculation result is consistent with the experimental data completely; (3) By the transient gas-liquid two-phase flow theory, it has established a new mathematical model for the free surface-pressurized flow. That it is, pressurized pipe transient flow model for the full flow part, stratified flow model for the free surface flow part, and the bubble flow for the transition part; (4) the calculation method for critical stability top slope of tailrace tunnel with sloping ceiling has been explored. It concluded that the second order minimal item in the continuous equation can not be omitted. However, there are some problem needing further study: In the physical model test, how to trace the movement of the wave front, interface pressure and variety of flow regime for the free surface-pressurized mixed flow under different work conditions; How to combine the continuous equation and momentum equation of gas-liquid two-phase flow with the governor equation of hydro-generator units, and then to deduce the calculation formula for the critical stability top slope of tailrace tunnel with sloping ceiling; Finally, it is necessary to explore and improve the relevant calculation software, and compare the calculation results of new mathematical model with the experimental data of model test.

本项目研究是将瞬变气液两相流应用于变顶高尾水系统明满混合流的机理分析和数学模拟。揭示分界面波动和流态转捩的规律，建立相应的数学模型和计算方法，编制计算程序，为工程设计提供可靠的理论基础和计算工具。推进瞬变气液两相流理论在实际工程中应用，提高变顶高尾水洞设计水平。为解决其他封闭管道系统明满流问题提供数值模拟途径和方法。