Research On Energy Dissipation Law Of Stepped Spillway Based On Gas-liquid Two-phase SPH Method

The paper uses the single-phase and gas-liquid two-phase SPH method to numerically simulate the flow of the spillway,and compares the simulated value with the experimental value.The results show that in the smooth spillway and stepped spillway,the two-phase SPH method simulates the water depth and flow velocity along the way The result is more accurate;the pressure simulation value of different steps of the 31-step spillway is compared with the test value.The pressure simulation value of the two-phase SPH has a smaller relative error with the test value,which verifies the feasibility of the two-phase SPH method to simulate the spillway flow.On this basis,combined with 6 types of steps,6 types of single-width flow rates and 8types of slopes,the two-phase SPH method is used to numerically simulate the water flow of the stepped spillway under various working conditions to analyze the water depth,flow velocity,and initial aeration point and pressure distribution law along the way.systematically study the relationship between the number of steps,single-width discharge and slope,and the energy dissipation rate of the spillway.The results show that:(1)There is falling water flow in the single-width flow q=0.1414 m~2/s in the30-step spillway,and falling water flow when the 40-step spillway q=0.1188 m~2/s.With the increase of the single-width flow or the number of steps,the falling water flow can be transformed into a gliding stream.(2)The water flow velocity gradually increases in the platform stage,increases to a certain extent and then begins to decrease.After a certain distance,the velocity gradually stabilizes,and the velocity increases with the increase of the single-width flow.(3)The size of the stepped spillway is fixed,and the position of the initial aeration point moves downward with the increase of the single-width flow;the single-width flow and the number of steps are fixed,and the position of the initial aeration point also moves downward with the increase of the slope.(4)On the level of the steps of the spillway,the pressure value starts to decrease from the concave angle of the steps,and then gradually increases,reaching the maximum value near 0.75 times the width of the steps;on the vertical surfaces of the steps,the pressure starts from the concave angle of the steps It gradually decreases along the vertical plane,and negative pressure appears after a certain height.The negative pressure value is the largest at about 0.9 times the height of the step;the maximum positive pressure on the horizontal plane and the vertical plane of the step is selected to analyze the pressure along the spillway,and the results show that the horizontal and vertical pressure of the stepped spillway develops in a wave-like manner,with the maximum value and the minimum value appearing alternately.(5)The single-width flow and slope are constant,and the energy dissipation rate of stepped spillway is much higher than that of smooth spillway.For spillways with six steps,the energy dissipation rate of 80-step spillway is relatively high,that is,when the total height of the spillway platform is constant,there is a certain The number of steps makes the energy dissipation effect of the spillway better under this working condition;the stepped spillway has a certain size,and the energy dissipation rate decreases with the increase of the single-width flow;the single-width flow and the number of steps are constant,and the total energy dissipation rate of the stepped spillway increases with Increases as the slope decreases.