Investigation and comparison of performance of butterfly valves by computational fluid dynamics (CFD) method

In this study, the flow characteristics of butterfly valves with different nominal diameters (DN50, DN150, and DN300) and different opening angles (10°, 50°, and 90°) were examined numerically using the Computational Fluid Dynamics (CFD) method. Clean water was used as the fluid, and inlet velocities were defined as 1 m/s, 3 m/s, and 5 m/s under various boundary conditions. The analyses were carried out using Autodesk CFD software, with a mesh independence test performed to ensure solution accuracy, and the obtained results were validated by comparing them with literature data. As the turbulence model in numerical modeling, the k-ε (standard) model was adopted. With this turbulence model, pressure distribution, velocity distribution, and head losses were analyzed, and evaluations were made over these parameters. Thus, the flow field behavior was revealed in detail, and the suitability of the turbulence model was verified. The findings indicated that the flow in all valve diameters occurred completely in the turbulent regime, as the Reynolds numbers were above 5×10⁴. It was observed that as the valve diameter increased, the Reynolds number and flow coefficient (Kv) increased, while at small opening angles, the pressure drop (ΔP) and loss coefficient (K) also increased. For example, under 90° full open and 5 m/s inlet velocity, the Accordingly, the flow capacity of the DN150 valve was about 9.12 times higher than DN50, while DN300 was about 4.28 times higher than DN150. At small openings, the pressure drop (ΔP) and loss coefficient (K) increased, whereas at larger openings, they decreased. The results obtained for ΔP, K, and Kv values were consistent with the ranges reported in the literature. This demonstrated that the model used was valid and that the determination of the flow characteristics of butterfly valves with different diameters and opening angles would make significant contributions to engineering applications in terms of optimum design and energy efficiency. Keywords: butterfly valve, computational fluid dynamics, turbulence model, k-ε, pressure loss