Numerical investigation of the formation of cavitation in the morning glory spillway

Document Type : Original Article

Authors

1 PhD candidate of hydraulic structure, civil engineering department, Isfahan University of Technology

2 Assistant professor of hydraulic, department of engineering, Hakim Sabzevari University

3 Professor, Water engineering department, Tarbiat Modares University, Iran,

Abstract

Morning glory spillway is one of the most susceptible cases for the occurrence of the cavitation phenomena. At the entrance of the spillway, the junction of the funnel entrance, the vertical shaft and within the elbow, cavitation is expected.  In the present study, the flow characteristics included the inlet and outlet discharge and the velocity and pressure in the elbow walls were calculated for Alborz dam spillway by using of Flow3D software and the results were compared with the experimental data. The comparison of the numerical results and the experimental data showed the good agreement between them. Also, the occurrence probability of the cavitation in various parts of the morning glory spillway was investigated using of the cavitation index. The results showed that the negative pressure occurs at the entrance of the spillway due to the flow separation. The cavitation was observed just at discharges less than submerged dischargeand there was notoccurrence probability of the cavitation in the submerged flow regime. In addition, the vertical shaft will act such as chute spillway in the case of the free surface regimeand because of the less friction and the high velocity, there was the occurrence probabilityof the cavitation. In the case ofthe submerged flow regime, duo to the low velocity, cavitation was not observed.Finally, there was the occurrence probability of cavitation at the beginning and the end of the elbow, but in the other points of the spillway, cavitation index was more than the critical cavitation index.

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References

منابع
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