The Hydraulic Characteristics Research For Stilling Pool With X-shaped Flaring Pier

Hydropower project is a major infrastructure project of a country,which is the key content that relates the project layout、engineering safety、engineering investment.In recent years,with the improving of the construction technology for water conservancy and hydropower project and with the constructing of numerous hydropower engineering,however,these projects are mostly distributed in the southwest, northwest mountain canyon, which have the engineering characteristics of high head, large flow, narrow valley, so the research of the flaring gate pier can get more attention. This paper begins to review from the development history of the flaring gate pier,combining with the former engineering background,which summarizes a series of flaring gate pier project and expounds the advantages and disadvantages of the Y-shaped flaring gate pier engineering. And we find the engineering destroying example and analyze the reason of the engineering problem,at the last we get the background and premise to develop the X-shaped flaring gate pier and we use the model test achievement that Northwest Water Conservancy Science Research Institute had done,the main contributions are as follows:First, we summarize the engineering application examples of the flaring gate pier in recent years and the failure examples of Y-shape flaring pier engineering, and then the cause of the destruction of the basin is analyzed.And we compare their differences.And we get that the discharge flow capacity of the X-shaped flaring gate pier than Y-shape flaring pier is slightly big, and the conclusion that the impact pressure of the X-shaped flaring gate pier on the floor than the Y-shaped flaring gate pier is smaller is obtained.Second, X type flaring pier engineering hydraulic jump equation on hydraulic calculation is studied, first reviewed the previous on some calculation results of calculation of Y type flaring pier hydraulic engineering, because of the difference of Y type and X type flaring flaring pier in size, it is impossible to use the calculation method of Y width the direct calculation of X type pier tail flaring pier, so this paper will be divided into X type flaring pier bottom water and upper water two flows, and at the end of the water jet for the pier, the upper water stocks do not generate pressure to lower water stocks, the momentum equation of water between the continuum between export lists in the pier and the end of the second at the same time, the conjugate water depth, water dam face force through the model test data summary simplified the range of some related empirical coefficient, then the momentum equations are simplified, the empirical coefficient into the momentum equation, the calculated conjugate depth ratio, know the depth before the jump can be directly obtained after the jump of water depth.Third, the hydrodynamic impact pressure on the floor for the X-shaped flaring gate pier is studied by means of dimensional analysis, describes one factor of pressure,which is related with the upstream and downstream water level difference, single hole flow, downstream water cushion depth, acceleration of gravity and the density of water.The pressure factor and the biggest impact pressure in the stilling pool has a good relationshi. The dynamic impact pressure data of the floor in stilling pool measured by the X type flaring gate pier of Gunnong, Ludila, Suofengyin, Shatuo etc. is used by regression analysis, we get a good expression that has good correlation.We can directly calculate the biggest hydrodynamic impact pressure by the upstream and downstream water level difference, single hole flow, downstream water cushion depth, acceleration of gravity and the density of water and other known conditions. It can predict maximum hydrodynamic pressure of preliminary design for engineering design personnel and can provide reference.Fourth, factors on the impact of fluctuating pressure monitoring data of a project are analyzed, including the flaring gate pier body, stilling pool length and end sill height, upper and lower water head difference, operating conditions and other factors, the conclusion will play a guiding role on the design.