The influence of reservoir water level on the hydraulic characteristics of spillway tunnel

Abstract The spillway tunnel for water discharging is very important in water conservancy and hydropower engineering. Spillway tunnel with inclined and elbow part near the outlet can be more easily adapted to the topographic and geological conditions than that near the inlet, and can limit the cavitation damage to the short tunnel near outlet. Therefore, it has been widely used in the case of discharging water with high head and large discharge. Cavitation induced by high speed flow may cause severe damage to the spillway tunnel surface. And aeration is a common measure for surface protection. Study on the hydraulic characteristics of water-air two-phase flow is of great significance for improving aeration effect. In this paper, the velocity, depth of water and Froude Number of spillway tunnel under different reservoir water levels are studied by using VOF method. The results show that the Froude Number decreases at first and then increases as reservoir water level becomes lower.