Hydraulic Characteristics In Downstream Of Discharge Gate

Turbulence is a widespread flow in nature,and fluid mechanics problems in many projects need to be solved by turbulence theory.Due to the complexity of the turbulence mechanism,the current law is not fully understood and grasped.In order to further reveal the turbulence mechanism of water flow,this paper studies the hydraulic characteristics of the flow in the scouring pit and the action law of the flow and sediment in the lower reaches of the dam by using the Doppler flowmeter.The following conclusions are obtained:(1)Using the Doppler flowmeter,three scouring pit shapes and three water flow observation experiments were carried out.The experimental data of 5 sections were collected in each working condition.By calculating and calculating the instantaneous physical quantities of turbulence,the corresponding mean and instantaneous values were obtained,and the characteristic quantities such as turbulence intensity,turbulent kinetic energy,Reynolds stress,velocity density component of velocity component,skew factor,Flat factor and so on.(2)The vertical distribution of the flow velocity is similar in all the working conditions,and the longitudinal flow velocity increases with the increase of the water depth,and reaches the maximum near the bed surface.In each section,the turbulence intensity changes little in the lateral direction;in the vertical and vertical,along the water depth increases and then decreases;in close to the bed,the turbulence intensity reaches the maximum,and then quickly reduced.The longitudinal Reynolds shear stress increases first and then decreases along the water depth,and decreases along the distribution.The general trend of turbulent kinetic energy along the depth distribution was increased first and then decreased.The velocity distribution of flow velocity was similar to that of normal distribution.As the depth of water increases,the probability density distribution of longitudinal and vertical pulsating flow rates deviates from the normal distribution.The vertical and vertical velocity deflecting factors were gradually shifted from zero by increasing water depth.In the position near the bed,the velocity flatness factor value was significantly higher than the other positions.(3)Using Doppler flowmeter,the data of the sand flow test in the plexiglass sinks along the 13 cross sections were collected.The turbulence kinetic energy,the Reynolds stress,the frequency density function of the velocity component,the probability density function of the velocity separation,the skew factor,the turbulence kinetic energy,the turbulence kinetic energy,the turbulence kinetic energy,Flat factor and other turbulent feature quantities.(4)With the increase of sediment concentration,the transverse,vertical and vertical pulsating intensities decrease gradually.For the same concentration of sandy water,the smaller the particle size was,the smaller the pulsation intensity was.Turbulence kinetic energy,longitudinal Reynolds shear stress also had a similar distribution law.The probability distributions of the flow rate of water and sediment flow were similar to the normal distribution.In the near wall region,the inclination factor of sediment flow is closer to 0 than that of water,and its flat factor was smaller than that of clear water,and the flat factor increases in the mainstream region.The energy of the flow was concentrated in the low frequency region.In the area near the bed,the energy of the horizontal,vertical and vertical flows increases,and the sediment movement promotes the development of the turbulence.In the main stream,the energy of the water flow decreases Sediment movement plays an inhibitory role in water turbulence.