Numerical Simulation Of Hydraulic Characteristics Of Spillway With Special Form Transition Ladder

The energy dissipation method of the integrated energy dissipator of the flaring gate pier,stepped spillway and stilling basin can not only use the stepped spillway to further improve the energy dissipation rate,but also use the waterless area formed behind the flaring gate pier to the steps and water tongue,avoiding cavitation damage on the step surface.However,with the continuous increase of the water head and the single-wide flow of the drainage building,in some projects,due to the insufficient aeration of the steps and the bottom of the water tongue,cavitation damage occurs on the step surface,and appears large and small cavitation pits.Even cracks appeared on the step surface,the above conditions seriously endangered the stability and safe operation of the drainage building.In this paper,the hydraulic characteristics of the flaring gate pier,stepped spillway and stilling basin integrated energy dissipator are studied on three special form transition ladder such as modified round,cuneiform and outer bulgy.To discuss the aeration and energy dissipation influence of the radius of the modified round transition ladder,the slope of the cuneiform transition ladder and the size of the outer bulgy transition ladder to the flaring gate pier,stepped spillway and stilling basin integrated energy dissipator.It provides a certain theoretical basis and practical direction for exploring the high water head and large single wide flow drainage building that can efficiently aeration and energy dissipation.The main conclusions of the study are as follows:(1)When the radius of the modified round transition ladder increases gradually from 3.13 mm to 4.17 mm,the aeration cavity length is longer,the water depth of the stilling basin is greater,the flow velocity is smaller,the energy dissipation rate is greater.At the same time,the larger radius can effectively reduce the distribution range of negative pressure in the stepped spillway,but the negative pressure in the step is larger;(2)The slope of the cuneiform transition ladder is within 5 ° to 15 °,the slope is larger,the water depth value of the stilling basin is larger,the flow velocity is smaller,and the energy dissipation rate is larger.At the same time,increasing slope can effectively increase the length of the aeration cavity,and the negative pressure will also increased.(3)The outer bulgy transition ladder with dimensions of 6.25 mm × 8.34 mm,12.50 mm × 16.67 mm,18.75 mm × 25.00 mm have a great influence on the hydraulic characteristics.Two negative pressure peaks appear on the step surface of the stepped spillway,and when the size of the outer bulgy transition ladder is within a certain range,the maximum negative pressure will move down to the junction area of the transition ladder and the uniform ladder.The outer bulgy transition ladder with dimensions of 18.75 mm × 25.00 mm has larger aeration range,larger stilling basin water depth value,smaller flow velocity and higher energy dissipation rate.(4)Comparing the modified round,cuneiform and outer bulgy transition ladder,it is found that the outer bulgy transition ladder have better energy dissipation effect than the cuneiform and modified round transition ladder in the integrated energy dissipator of the flaring gate pier,stepped spillway and stilling basin.