Hydraulic Characteristics And Block Shape Design Of Swirl Blocking Spillway

The horizontal swirling obstruction and diffusion composite internal energy dissipation spillway is a new type of internal energy dissipator with blocking structure in the horizontal swirling discharge tunnel,and can be applied to flood discharge and energy dissipation under higher head.Set blocking will produce the effect of supercharging and deceleration,but the systematic study on the effect of obstruction on the hydraulic characteristics in the cyclone hole has been studied.The effect and mechanism of the blocked supercharging and deceleration have not been further studied.Therefore,this paper is based on the hydraulic characteristics model test of the cyclone obstruction compound internal energy dissipation tunnel conducted by the National Fund Project,and combined with the results of other multiple body types,using data consolidation,dimensional analysis,and theoretical analysis methods,for different obstructions.The hydraulic characteristics of the orifices,different spinner orifices,different upstream and downstream water levels,and different vent holes were analyzed.The effect and mechanism of the pressurized deceleration of the swirling flow obstruction were studied,and the design method of the cyclone obstruction was proposed.Research indicates:(1)The obstruction makes the swirl flow in the cavity of the swirl hole more stable and the flow changes smoothly;the pressure on the inner wall of the swirl hole increases significantly,the flow velocity decreases,the cavity diameter decreases,and the swirl angle increases.At the same time,the hydraulic characteristics are characterized by segmental changes in each segment of the cyclone hole,and have good retention along the cyclone segment.The water flow from the cavity to the turbulent gas-water two-phase flow is gradually changed at the blockage,and the hydraulic characteristics change drastically.(2)Based on experimental results such as flow velocity,the swirling flow of the cavity is verified as a free-vortex motion law.Based on the theoretical derivation,the relationship between the hydraulic characteristics of the cross-section before and after the cyclone obstruction is obtained.According to the analysis,in the front and rear cross sections of the cyclone obstruction orifice,the wall pressure ratio is inversely proportional to the square of the cavity radius ratio,and the tangent ratio of the swirl angle is proportional to the ratio of the section radii.(3)After the obstruction is set,there will be a large pressure difference before and after obstruction,which will increase the pressure before obstruction;In the cyclone hole,the pressure of the wall of the cyclone cavity will increase due to the incompressible nature of water flow and strong centrifugal force.Go upstream.This supercharging characteristic exhibits a deceleration characteristic due to the mutual conversion between pressure energy and kinetic energy when the energy is conserved.This is the principle of supercharging and deceleration that is blocked during the swirling of the cavity.The principle of supercharging and deceleration is the embodiment of the mass conservation of rotational flow,conservation of energy,and conservation of angular momentum in the cavity before and after the rotating flow and the constricted orifice of the swirl flow.(4)When no blockage is set,the pressure at the orifice of the spinner and the pressure after the energy conversion section decrease with the increase of the upstream and downstream water level difference,the aperture of the spinner n,and the square of the Fr2 of the spinner aperture.The linear law changes;after the obstruction is set,the pressures of the two sections increase with the increase of the obstruction m,and decrease with the increase of the Fr2 of the spinner;the starter orifice and the cyclone obstruction orifice The pressure coefficient between the initial sections is linearly increasing.(5)A block size design method and illustration with a specific design example have been given.The hydrodynamic characteristics of the cyclone obstruction compound internal energy dissipation flood tunnel,the pressure-increasing deceleration effect and principle analysis of the obstruction,and the proposed blocking body design method,the theoretical analysis of the hydraulic characteristics of the energy dissipater,and the energy dissipation worker shape design And application,has important reference value.