Research On The Influence Of The Bottom Edge Type On The Hydrodynamic Characteristics Of The Radial Gate

Water release structure is an important part of water conservancy projects,which plays a decisive role in the safe operation and benefit.Gate,as the throat,is the key component of the safe operation of water release structures.Radial gates are widely used in water release structures because of small hoisting force,with no gate slot,and good hydraulic characteristics.The bottom edge type of radial gate has great influence on flow pattern,discharge capacity and vibration characteristics.In this paper,the method of combining physical model test and numerical simulation were used to study the flow pattern,time-averaged pressure and fluctuating pressure characteristics of the radial gates with four bottom edge types(forward-inclined arc type,backward-inclined arc type,semi-circular arc type and elliptical arc type)under three openings(6cm,8cm and 10cm)and three flow rates(120m~3/h,140m~3/h and160m~3/h).The purpose is to explore the hydrodynamic characteristics of different bottom edge types of radial gates,select safe and reliable bottom edge type of radial gate,provide technical support for engineering design and operation,and provide reference for sluice operation.The main research results are as follows:(1)Based on the physical model test and numerical simulation,the flow patterns and flow fields of four types of bottom-edge radial gates under different working conditions were analyzed,and it is concluded that the forward-inclined arc type and backward-inclined arc type bottom-edge radial gates have better discharge capacity.Under low water head,there is a surge in the upstream flow of the radial gate at the bottom edge of the backward arc type and elliptical arc type,and the downstream tail water is more likely to submerge the bottom edge of the gate.(2)Based on the physical model test and numerical simulation,it was obtained that the time-averaged pressure distribution on the radial gate panel conforms to the distribution law of hydrostatic pressure,and the time-averaged pressure increases with the increase of the water depth.The negative pressure at the bottom edge of the backward-inclined arc type is not obvious,and the other three types of radial gates have obvious negative pressure at the bottom edge near the upstream side,the negative pressure of the forward-inclined arc type is relatively small,and the negative pressure of the semi-circular arc type is the biggest.(3)Based on the model test,the fluctuating pressure amplitudes of the four bottom-edge types of radial gates are all small and all deviating from the normal distribution,and the forward-inclined arc type has lower kurtosis than the other three bottom-edge types under the conditions of 6cm opening and 160m~3/h flow rate.Due to the bottom edge of the gate is flooded with water tail,the amplitude of the fluctuating pressure of the four bottom edges is large,and the amplitude deviates from the normal distribution under the conditions of 10cm opening and120m~3/h flow rate.The forward-inclined arc type,backward-inclined arc type and elliptical arc type all have high kurtosis at the central axis of the bottom edge.(4)Based on the model test,under the conditions of 6cm opening and 160 m~3/h flow rate,the main frequency range of fluctuating pressure of four bottom type radial gates is about 0?2Hz,and the fluctuating energy mostly distributes in the range of 0?5Hz,which belongs to low frequency pulsation.Under the condition of 10cm opening and 120 m~3/h flow rate,the main frequency is relatively high due to the submerged bottom edge with the downstream side of the gate,and the main frequency is in the range of 0?5Hz.The energy of forward-inclined arc type,semi-circular arc type and elliptical arc type mostly distributes in the range of 0?7Hz,and the energy of backward-inclined arc type mostly distributes in the range of 0?10Hz.In conclusion,from the comprehensive consideration of flow pattern,time-averaged pressure and fluctuating pressure,the hydrodynamic characteristics of the radial gates with the forward-inclined arc type bottom edge are the best,and it is recommended for use in the actual project.