The Impact Study Of The Combination Of Pre-aerator Angels And First Stage Step Angle On Hydraulic Characteristics Of The Combined Energy Dissipation Project

With the rapid development of water conservancy and hydropower projects,the flare gate pier with step overflow dam and stilling pool dissipator gradually attracted everyone's attention.Due to its high energy dissipation rate and saving engineering investment,it is widely used in many high dama flood discharge projects.However,with the increase of single-width flow rate and water head,cavitation,cavitation erosion and low energy dissipation have become more and more serious.Especially,the discharge flow is prone to cavitation damage when flowing through the stepped surface of stepped overflow dam phenomenon.At present,most of the researches on the flaring piers with step overflow dam and stilling pool integrated energy dissipater are mainly based on model tests.The research objects are often aimed at the overall energy dissipation effect and aeration of step overflow dam However,there is not much influence on the aeration and the negative pressure of step surface in flare gate pier with step overflow dam and stilling pool dissipater if the connection form between step overflow dam and WES under flaring pier description.In this paper,based on the sea surface overflow hole of Ahai Power Station,the physical model test was used to simulate the transitional step between different stepchamps and different step angles,and to analyze the integrated dissipative energy dissipation of flaring gate piers with step overflow dam and stilling basin The effect of the spillway dam surface aeration,the dam flow pattern,the pressure distribution,the flow velocity distribution and the energy dissipation and other hydraulic characteristics of the stairway spillway is more suitable for large single-wide flow and optimize the footwall overflow The connection between the flow dam and the WES surface provides the reference.The main research results are as follows:(1)Experimental study,different reservoir water level and flow rate are changed,and the aeration characteristics of overflow dam with flare gate pier with step overflow dam and stilling pool integrated dissipater are compared and analyzed.Distribution,velocity distribution and energy dissipation rate and other hydraulic characteristics.(2)The results showed that the length of the aeration cavity increases with the increase of the first stage table angle;and the cavity negative pressure decreases with the increase of the first stage table angle,and with the increase of the first stage table angle,the maximum cavity negative pressure from the second step of the facade to the first step of the facade;the energy consumption rate increases slightly with the increase of the first stage table angle and the energy dissipation effect is better when the step is up than fall or level.(3)The results show that the length of the bottom cavity and the concentration of the aerosol are gradually increased with the increase of the pre-aerator angels,and the increase of the first table angle does not exceed 10 °.This can effectively protect the ladder to prevent cavitation damage.And the flow rate decreases,the pressure increases,the energy dissipation rate also increases,more conducive to the protection of the downstream.So the pre-aerator angel is 10 °and the first stage table angle of 10 ° is the best combination.In this paper,the model test is carried out only on the form of the connection between the spillway and the WES surface under the wide-tail pier under the aegis and the first step angle.For other connection forms such as changing the height of the aerator and changing the slope of the step overflow dam still need follow-up study.