Numerical Simulation Of Inclined Step Spillway

Based on Chinnarasri’s experimental results,simulated characteristics of flowregime,aeration and energy dissipation of inclined step, the main research as follows:1) firstly, introduces research background of this paper, summarized the history,research trend of stepped energy dissipater,and some new stepped energy dissipaters.Summarized methods of flow regime definition, the position of air entrainment,airentrainment mechanism etc. Provide theoretical basis of numerical simulation.2) Use standard k~ε model,Mixture model,Quadrilateral unstructured gridno slip wall boundary condition as numerical method simulate the two phase flow,inlet boundary divided as water inlet and air inlet and the discrete method of pressure-Velocity coupling is PISO method.3）Defined air water interface. Simulated regime of horizontal step andinclined step,find that,both in horizontal step and inclined step there are three regime sas nap flow,transition flow and skimming flow,but in inclined step,the nap flow isdifferent from the horizontal step,which can be divided as adherence overflow,drop flowand vortex flow. It also found that the upward angle of the inclined step has a littleeffect in the flow regime.4）through the research of the characteristic of air entrainment about inclinedstep,we get the result that vortex air concentration increased along the spillway, andchange a little in the section between the step corner and water-air surface,in the laststep,air concentration had a slightly decrease. The air concentration increase withdistance from the inlet and the increase of the discharge, and also with the increaseof the inclined angle. The author point out that inclined angle can’t increase unlimitedbecause of cavitation may accord when the angle too large,and this need a furtherresearch to verify.5）defined energy dissipation rateη, and theoretically annalized influence factorson η, fined that η have a relationship whit Froude number F0，drop number FD，thespecific value of hc/d in witch hcis the critical water depth and d is the stephight.through the simulated result get that ηdecrease with FDand hc/d and increasewith θ, and also give empirical relation about FD~η and θ~η and applicationrange of these relation.