<![CDATA[Pipe bends in hydropower penstock systems effected pressure drop due to changes in fluid flow direction. Pressure drop in piping systems can decrease overall system efficiency. This study aims to analyze the effect of diameter expansion variations (1.25D and 1.5D) and connector angle variations (10o–90o) on pressure drop in 90o pipe bends using Computational Fluid Dynamics (CFD) simulation. The study employed an experimental approach based on ANSYS Fluent 2019 R3 simulation with 13 design variations, an inlet velocity of 7 m/s, water as the fluid, and the k- realizable turbulence model. Simulation results showed that the 1.25D design with a 10o connector angle produced the lowest pressure drop of 1,094.350 Pa, which is 47.7% lower than the standard 1D design with a pressure drop value of 2,090.634 Pa. Design 1.5D with a 90o connector angle yielded the highest pressure drop of 21,355.714 Pa, an increase of 921.51% from the standard 1D design. Increasing the connector angle consistently raised pressure drop in a non-linear pattern across both diameter variations. The 1.25D+10o design proved most optimal by combining effective flow velocity reduction with a gradual geometric transition, thereby minimizing flow separation and turbulence. These findings are expected to contribute to the optimization of hydropower penstock pipe design to improve overall flow system efficiency.]]>
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