Investigation of cavitation in location of change slope Surk Dam spillway using hydraulic lab modeling

Cavitation is one of the hydraulic phenomena that its occurrence caucus destroying the hydraulic structures. Chute spillway is an example of hydraulic structures that cavitation may be occurred. In this work, cavitation in chute spillway of Surk dam, which it have a rapidly change slope in chute path, has been studied using physical modeling. The physical model was made by plexiglass with scale of 1:50 and dynamic similarity between the model and the prototype was considered based on Froude number. The experiments were conducted in 5 different flow rates and pressure, velocity and flow depth were measured in the central axis and side of the wall. In this study, Falvey criterion (1990) was used for commenting of cavitation index. The results showed that the calculated cavitation index was in range of 0.25 to 1.8. In this range Falvey recommended to prevent the risk of cavitation, it is required the concrete surface of the chute spillway should be lining with a smooth materials.