| The short pressure discharge hole is a common discharge structure in high dam engineering.The falling sill type aerated erosion reduction is also widely used in various discharge projects and has achieved more results.However,the depth of research on the characteristics of strong turbulent and sudden splashing flow in aerated water body with aerator is limited.The prototype observation shows that when the short pressure discharge hole with aerator operates at high water level,the aerated water body has adverse hydraulic characteristics,such as paroxysmal sharp rise and fall of water surface,periodic splash of water wings hitting the roof cover plate.In this project,the high head short pressure discharge hole with aerator is taken as the research object,and the large-scale hydraulic model test method is adopted to study and analyze the turbulence characteristics and related influencing factors of aerated water body under different flow conditions,ventilation modes and aerator shapes.1.Some research results on turbulence and sudden water wing splashing in aerated flow at home and abroad are collected;The technical route,model setting,working condition formulation,test method and characteristic parameters and indexes of turbulent water wing are introduced.2.The periodic splashing of aerated water with high head and short pressure discharge hole is revealed by the model test;The turbulence characteristics and water wing characteristics of aerated water under different operating head conditions were studied and compared;The water surface wave rate the root mean square of water surface wave and the cavity backwater wave rate were calculated root mean square of fluctuating pressure The degree of turbulence is measured by the parameters of turbulence,and the severity of water wing is measured by the lift rate of water wing;The results show that the rise height of the water wing,the length of the aeration cavity,the length of the backwater,the average ventilation and the ventilation rate increase linearly with the inlet head H;Inflow conditions,impingement angle of water tongue,amplitude of cavity backwater,and rise of water wing are progressive layer by layer;When the angle ratio R(impact angle and critical impact angle 11~°When the angle ratio is greater than 1.4,the water wing uplift rate increases sharply and increases linearly with the angle ratio.3.Taking the high water head(H=85m)as the typical working condition,the influence of different ventilation modes,different inflow conditions(H=75m,77m,82.5m)and different aerator shapes on the turbulent characteristics of aerated water was studied.The results show that the strong turbulence area of the chute flow is from the inner edge of the aerated drop bucket to the reverse arc flip bucket;The larger the ventilation area is,the stronger the turbulence is;The large swing of backwater in the cavity during intermittent ventilation aggravates the turbulence of aerated water,the intermittent upward uplift of water surface and the splash of water wings.The results show that the turbulence in the upstream of the impact zone of the inner edge of the unsymmetrical inlet tongue of the outlet is strengthened,and the turbulence in the reverse arc section is weakened.The larger the oblique angle is,the greater the influence is;The aerator is changed to-3.9~°The falling angle or the aerator moving forward 5m can shorten the impact point of the water tongue of the aerator and make it far away from the reverse arc section,so as to reduce the cavity backwater and the fluctuation range of backwater,and reduce the water oscillation in the bottom cavity.As a part of the general project of National Natural Science Foundation of China"Research on the mechanism of turbulent splash burst in aerated water with high head and short pressure discharge hole",this paper lays a certain foundation for the next stage research on the mechanism of turbulent splash burst in aerated water. |
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