The Analysis of Diameter Expansion and Connection Angle Variations Effects In Hyropower Penstock Pipe Bend on Pressure Drop Using Computational Fluid Dynamics Simulation

Agung Widodo; Dony Hidayat Al-Janan; Aldias Bahatmaka

doi:10.24036/wb52b413

Authors

Agung Widodo Universitas Negeri Semarang
Dony Hidayat Al-Janan Universitas Negeri Semarang
Aldias Bahatmaka Universitas Negeri Semarang

DOI:

https://doi.org/10.24036/wb52b413

Keywords:

Penstock, Hydropower Plant, Pressure Drop, CFD, ANSYS

Abstract

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 (10^o–90^o) on pressure drop in 90^o 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 10^o 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 90^o 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+10^o 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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