| The vortex is a classic and complex phenomenon before the inlet of the hydropower station.When the inlet is submerged,the vortex is easy to form,which is very unfavorable to the operation safety of the hydropower station.It is a key concern in the design and operation for the hydropower power station.It is a new type of power station inlet type of multi-level stop-log gates intake for the consideration of ecological environment protection,which draws high temperature water from the surface of the reservoir.The effect of stop-log gates on the vortex in front of intake and the method to avoid the critical subm erged water depth of the inhalation vortex need to have further research.It is a problem to be solved that few related studies focused on this new type of multi-level stop-log gates intake.In this paper,multi-level stop-log gates intake of a hydropower station is taken as the engineering background.The combination of numerical simulation and physical model test is used to study the hydraulic characteristics of the inlet,especially the characteristics of the inlet vortex and the critical submerged water depth.1.Established a three-dimensional numerical model of multi-level stop-log gates intake and verified the reliability of the numerical calculati,on with the model test.The characteristics of multi-level stop-log gates intake flow were analyzed,RNG k—? model and th e VOF two-phase flow model were employed to the numerical simulation to solve the three-dimensional turbulence problem of the inlet.The numerical simulation of flow velocity,pressure and head loss coefficient agreed well with the experimental observations,which can be used to study the hydraulic characteristics of multi-level stop-log gates intake,2.The nutmerical simulation of the vortex phenomenon on the surface of the intake behind stop-log gates is carried out.The calculation uses the higher precision mesh and VOF geometric reconstruction method to simulate the inlet flow field of the prototype specific stop-log gates intake,and combined with the large scale model test vortex observation results for comparative analysis.The comparison results show that the two agreed well.The numerical model used can better simulate the characteristics of the flow pattern,vortex diameter and vortex type of vortex appears behind the stop-log gates.3 Reveal the law of the submerged water depth and the flow and inlet vortex generation and development of the stop-log gates.Combined with the numerical simulation and model test results,the characteristics of the inflow vortex are analyzed from the angles of the vortex of the inlet of the stop-log gates the diameter of the vortex,the depth of the maximum depression,the continuous depth of the multi-turn spiral motion and the Q'value distribution of the inlet water surface.The results show that:At the top of the stop-log gates,with the submerged water depth decreases or the flow rate increases,the vortex intensity gradually increases.4.The Froude number were centered on controlling parameters to test and numerically calculate the critical submerged water depth around the inlet of the stop-log gates.Through the model test,the critical submerged water depth in the water inlet of the power station is obtained,and then the numerical simulation is used to calculate the vortex of the larger and smaller Froude number extension conditions,and the critical submerged water depth of the inlet of the stop-log gates is obtained comprehensively.5.The calculation formula for the critical submerged water depth of the stop-log gates hydropower station were proposed.Based on the analysis of the influencing factors of the formation of vortices,the dimensional analysis of the critical submerged water depth is carried out,and the relationship between the critical submerged water depth SID and the Froude number Fr is obtained,and the integrated model and numerical data are fitted.The formula for the critical submerged water depth of the new kind of multi-level stop-log gates intake were obtained.In summary,the research contains two innovations.On the one hand,the combination of numerical simulation and model test is used to reveal the law of vortex generation and development of the multi-level stop-log gates intake hydropower station,On the other hand,the calculation formula for the critical submerged water depth of multi-level stop-log gates intake were proposed.The research results have strong scientific significance and application prospects,and can provide scientific reference for engineering design and safe operation of similar hydropower station inlets. |
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