Study On Body Type Optimization Of Gate Slot Of Jishi Gorge Middle Orifice Discharge Hollow

At present, the research of cavitation brings great progress to the design of gate slots in the pressure flows. However, for the free-flow plane working gate slot, the hydraulic characteristics are much more complex than the gate slot under high water and pressure flow. Furthermore, there is no criterion to follow.The Jishi Gorge hydropower station, which is located in Xunhua county, Qinghai province, is the fifth large stepped station of"Long-Qing segment stepped programming"of Yellow River's upstream trunk. Two plane gates are setting paralleled. The upstream one is the emergency gate, and the downstream one is the working gate. According to the hinge's holistic disposal, a groovy gate slot is adopted. The working gate has the local opening role, so the flow condition is quite complicated, and the cavitations problem is very serious. So, studying the relations between the type of gate slot and cavitations and recommending an optimized type to ensure the safety of the project is imperative under the situation.With the development of technology, theoretical analysis, experimental research and numerical simulation are becoming the main methods of hydraulics. The virtues of the model practical and the numerical simulation are applied neatly, and the theoretical analysis is also combined in this paper. The flow modality and the pressure distributing around the gate slot are analyzed systematically and the body type is optimized. The main researches mage by this paper include several aspects as followings:At first, through the hydraulic model practice, the convert bank, the hold down board behind the gate slot, the stagger space, the round corner and the gradient slope of downstream are modified and optimized. The elementary optimized slot type is gained. The pressure of testing points is improved observably, and the flow character runs to smooth.Second,the mathematical model, which reflect the essence of the project is set up. Efficient, accurate compute method is also explored. The numerical simulation methods were brief summarized in the paper. Based on the shapes of free surface, the free surface is divided into a relative stable one and a rather fluctuant one. Water current problems including relative steady and rather fluctuant free surface were disposed accordingly. Flow control equations were given, relative steady and rather fluctuant free surface were treated with the rigid-lid hypothesis method and the VOF method respectively. By modifying the control parameters continually, the compute results, which consistent with the test data are gained. It improved that the result gained from the numerical method in this paper is credible, which can be used in the type optimize of the gate slot.At last, the mathematical model and the arithmetic is used in this paper. Aim at different type parameters, series computing is carried out, and a pressure-relationship was defined. The influential factors of the pressure-relationship and the flow characters were studied, which included the width-depth rate, the stagger space rate, the round corner rate and the gradient slope of downstream. By doing so, the reliable analytic evidence can be provided.