AN EXPERIMENTAL AND NUMERICAL STUDY OF FACTORS INFLUENCING THE SCOUR DUE TO THE COLLISION OF WATER JET IN STILLING BASIN FLOOR

Fadhil M. Al- Mohammed, Ali T. Jassim, Hamid A. Abbas

Abstract


This study based on the laboratory experiments and numerical analysis to study the configuration of the local scour downstream of hydraulic structure result by free water jet. This jet will have a high kinetic energy making it able to transport the sediment particles downstream of the impinging area, thereby forming a scour hole. The purpose of conducting this study was to evaluate the minimum distance of scour hole from the nozzle jet. One hundred and thirty-eight runs were carried out to investigate the local scour downstream the hydraulic structure under clear-water conditions with different discharges, tail water depths, and jet angles. Two types of jets were used, normal jet and dispersion jet. Results indicated that minimum distance of scour increase with increasing densimetric Froude number and jet velocity. The increase in tail-water depth decrease the distance to the scour hole until access to a critical depth at which the scour hole is largest possible after that the distance back to become large when the depth is overstepping the critical value. The optimum jet angle depends on the jet velocity, with a value of 20° for jet discharges 60 and 80 L/min and 40° for jet discharges 100 and 120 L/min. The dispersion jet technique where used to investigate its effects on the scour processes where its observed that the scour hole resulted small than the scour hole from case of normal jet, Also, the numerical simulation was used by (FLOW3D) software program to investigated from the result of the experimental work, the results showed an acceptable agreement with the experimental results with percentage of error equal to (% 6.28).

http://dx.doi.org/10.30572/2018/kje/100204 


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