Laminar Pressure Loss Coefficient in Close Coupled Fittings

Abstract

Close-coupled fittings are widely used in piping system to change the direction of the fluid and to connect pipes. These fittings cause losses and these losses play a significant role in the total pressure loss in a duct system. Numerical simulations were performed using Fluent on laminar flows in a circular pipe to obtain pressure loss coefficients associated with different fittings of two elbows and three elbows. Each configuration was studied with different intermediate distances between fittings of 0, 1, 3, 5, and 10 pipe diameters. It was observed that for a Reynolds number of 100 and for an intermediate distance less than 5 pipe diameters, the pressure loss coefficient for the coupled fittings was less than that of the uncoupled fittings. While the fittings become uncoupled when the intermediate distance was greater than 5 pipe diameters. Variation of velocity along the axis of the pipe was analyzed to understand the mechanism of the pressure loss for various fitting configurations with different intermediate distances.