Numerical analysis of the flow characteristics of dam discharge valves under different operating conditions

Valves are mechanical components that control or regulate the flow of fluids, such as water and gas, through a confined section. Valves with different design characteristics exhibit significant variations in flow behavior. In this study, the flow characteristics of butterfly valves, square slide gate valves and cone valves, widely utilized in dam operations, were analyzed under various operating conditions and a comparative evaluation was conducted. Understanding the flow characteristics of valve systems used for discharge and regulation purposes, especially in structures called bottom outlets of dams, is great importance in terms of dam design and operation processes. In this study, the flow characteristics of square slide gate valves, cone valves, and butterfly valves of the exact dimensions were analyzed using the Computational Fluid Dynamics (CFD) software Ansys Fluent at opening ratios of 25%, 50%, 75% and 100% under inlet pressure conditions of 2, 4, 6, 8, and 10 bar. The analyses evaluated volumetric flow rate, pressure losses, pressure distribution, velocity distribution, and streamlines, providing a comparative assessment of the obtained results. An examination of the flow coefficient (Kv) values of the valves revealed that the highest Kv values were obtained for the square slide gate valve at opening ratios of 100%, 75%, and 50%, with values of 99.679 m³/h, 50.406 m³/h, and 26.915 m³/h, respectively. The butterfly valve exhibited higher Kv values than the cone valve at 100% and 75% opening ratios, with 53.953 m³/h and 25.147 m³/h values, respectively. However, at 50% and 25% opening ratios, the cone valve demonstrated higher Kv values than the butterfly valve. At a 25% opening ratio, the Kv value of the cone valve was 9.266 m³/h, slightly exceeding the Kv value of 8.992 m³/h observed for the square slide gate valve. This comparative analysis underscores the importance of selecting the appropriate valve type for specific operating conditions in dam applications, providing critical insights for dam systems' design and operational efficiency.