| In addition to the direct influence of the shape structure of the side inlet / outlet on its own hydraulic characteristics,the connecting sections on both sides-open channel and water conveyance tunnel can also indirectly affect its hydraulic characteristics by affecting its inflow conditions.At present,there is a lack of research content in this regard,and there is no relevant description to guide the design in the latest design code NB / T 10072-2018 for pumped storage power station.Therefore,this paper adopts numerical simulation method to study the influence of the reverse slope section of the open channel on the hydraulic characteristics of the side inlet / outlet and the optimization of the hydraulic characteristics of the side inlet / outlet with the S-shaped tunnel.The main research contents and results are as follows:(1)Validation of numerical simulation method for side inlet / outlet.Taking the side inlet / outlet of the lower reservoir of a pumped storage power station as an example,the hydraulic characteristics such as head loss and velocity distribution are numerically simulated.Based on the results that are derived from the comparison of the numerical simulation results and model test results,the feasibility and accuracy of numerical simulation method are verified.(2)The influence of the reverse slope section of the open channel on the hydraulic characteristics of the side inlet / outlet is studied.Six groups of mathematical models of reverse slope with different slope ratios from 1:1 to 1:6 are established.Numerical simulation was carried out under the inlet and outlet conditions of dead water level.Under different slope ratios,the hydraulic characteristics of side inlet/outlet are compared and studied,including the head loss,velocity distribution of trash rack section and flow pattern.The results show that when the slope ratio of the reverse slope section ranges from 1:3 to 1:4,the side inlet / outlet can obtain good hydraulic characteristics under both inlet and outlet conditions.(3)The optimization ways of hydraulic characteristics of side inlet / outlet with Sshaped tunnel is studied.Under the discharge condition of dead water level,the side inlet / outlet with the S-shaped tunnel are numerically simulated,and its calculation results are compared with the numerical simulation results that belong to the side inlet/ outlet with the straight tunnel.The comparison results show that the characteristics of the side inlet / outlet with the S-shaped tunnel do not meet the hydraulic design requirements,and the reason is the S-shaped tunnel;In order to optimize the hydraulic characteristics of the side inlet / outlet,firstly,the internal flow pattern of the S-shaped tunnel is analyzed,and then according to the analysis results,it is determined to optimize the hydraulic characteristics of the side inlet / outlet mainly from the perspective of the shape optimization of the S-shaped tunnel.On this basis,two optimization ideas of the shape of the S-shaped tunnel are put forward from the perspective of curvature,and three indexes are selected to compare and select the optimization ideas.The results show that when the S-shaped tunnel is optimized by using the noncentrosymmetric layout method in the optimization idea 1,and keep the ratio of the two arc radius is less than 1,the hydraulic characteristics of side inlet / outlet with S-shaped tunnel can be optimized and improved.The smaller the value of b,the better the improvement effect of hydraulic characteristics. |
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