Study On Prediction Method Of Free Jet Scour Hole Based On Impact Pressure

At present, energy dissipation of ski-jump type is mostly adopted in high dam engineering. Estimating depth and sphere of the scour hole of downstream is required, which can avoid the influence on stability of side banks slope and dam body. Exact prediction of bedrock scour depth makes important sense in both energy dissipation and scour protection design for high dam downstream.Based on analysis of flow characteristics in a scour hole, the prediction method of free jet scour depth based on impact pressure is put forward in this thesis. The quantified relationship between the scour depth and the impact pressure as well as its distribution coefficient is learned about by hydraulic model experiment and numerical simulation. The main researches made by this thesis include several aspects as followings:First, with researched results of impinging jets, the diffusive characteristics for an submerged turbulent impinging jet in a scour hole are analyzed in detail, the disciplinarian of impact pressure on the bed exerted with the jet flow was given. Based on analysis of rocky beds scouring characteristics, the prediction method of free jet scour depth based on impact pressure is put forward.Second,3-D numerical turbulent model, which can suitably simulate free jet is set up.Efficient,accurate compute method is also explored. After the model is verified,numerical schemes are yielded.And then aiming at impact pressure in different operating mode,series computing is carried out.The results have reference value for the model experiment.At last,the scour depth under each distribution of impact pressure is measured by model experiment.Then the results are verified by estimating formula which is suitable for this experiment.Based on the analysis of test data,the estimating formula of scour depth based on impact pressure as well as its distribution coefficient is set up. These results in this thesis have reference value for further research on scouring.