Study On The Blocking Effect Of Different Blockages On The Swirling Flow In The Cavity Of The Swirlingg Spillway Tunnel

Blocking composite internal energy dissipation is a way of adding blocking-gradual expansion facilities in the horizontal swirling flood discharge tunnel,which can significantly increase the pressure of the horizontal swirling tunnel,reduce the flow velocity in the swirling flood discharge tunnel,increase the energy dissipation rate,and improve internal cavitation cavitation conditions.(1)The discharge flow law conforms to the pressure orifice outflow law.The blocking ratio has an effect on the flow coefficient of the swirler throat and the blocked orifice.The flow coefficient of the swirler throat and the blocking ratio are negatively correlated,and the blocked orifice The flow coefficient is about 0.2 when the blocking ratio is small(m=0.2),and about 0.55 when the blocking ratio is large(m=0.5).(2)Under different obstructions,the pressure in each section presents a slightly larger eccentric circle distribution at the bottom;the change of the obstruction ratio has a reduced impact on the obstructed section,which mainly affects the pressure of the horizontal swirl tunnel section,and when the obstruction ratio is smaller(m=0.2),the maximum pressure is 122x9.8kPa,and when the blocking ratio is larger(m=0.5),the maximum pressure is 184×9.8kPa,and the increase effect is obvious.(3)The average flow velocity of the section has an increasing trend in the spinner,and gradually decreases after exiting the spinner,and sharply increases in the blocked section;the flow velocity in the radial direction increases first and then decreases from the cavity wall to the cavity There is a maximum value at the water-gas interface.As the blocking ratio increases,the cross-sectional flow rate decreases,and the larger the blocking ratio,the faster the flow rate decreases.(4)The larger the blocking ratio,the smaller the blocked orifice area,the smaller the diameter of the swirl cavity,the larger the swirl angle,and the more stable the water flow rotation(5)When the smaller blockage ratio m=0.2,the water flow cavitation number of the entire energy dissipator is small,about 0.5 to 1.0.When the blockage ratio m=0.5,the water flow of the entire energy dissipator is empty.Most of the cavitation numbers are greater than 2.0,which reduces the possibility of cavitation cavitation and greatly improves the safety of cavitation.(6)At different blocking ratios,the total energy dissipation rate can reach more than 85%,which can meet the energy dissipation requirements of general drainage structures.The larger the blocking ratio,the greater the energy dissipation rate but the larger the blockage ratio is,the adverse effect on the discharge will be produced.