FRICTION LOSSES IN PIPES

Pipe friction losses play a critical role in pump sizing, pressure regulation, and the reliability of hydraulic and power systems. Reducing these losses directly improves energy efficiency and operational performance. This study aims to quantify and analyze pipe friction losses in a recirculation test loop, focusing on the relationship between flow regime, Reynolds number, and pressure loss. Differential pressure transducers, volumetric flow meters, and viscosity corrections were used to measure velocity profiles, calculate Reynolds numbers, and determine friction coefficients using the Darcy-Weisbach formula. The results confirm the expected decrease in the friction coefficient with increasing Reynolds number across the tested range, consistent with a transition to turbulent flow without full roughness control. The pressure loss per unit length increased approximately with the square of the velocity, while the hydraulic gradient decreased with increasing Reynolds number, indicating improved momentum transfer efficiency at higher flow rates. The data trends in both datasets are consistent internally, with friction coefficient values ranging from 0.049 at lower Re values to 0.038 at higher Re values, and the pressure loss coefficients exhibit similar measurement behavior. These results provide validated empirical benchmarks for piping system design, enabling more accurate pump and pipeline sizing and supporting energy-efficient valve and diameter selections. Future studies should extend this analysis to include different pipe roughness classes and complex fittings to further improve predictive correlations.