Velocity Development in Rectangular Channel with Different Bending Angle

Abstract

This research investigates the study of fluid dynamics in a rectangular channel, focusing on the effect of bend shapes on velocity profiles and flow efficiency. Computational Fluid Dynamic (CFD) simulations of velocity and pressure distributions are carried out in confined flow spaces, with three bend angles 90°, 120°, and 150°. The simulations use a uniform inlet velocity of 10 m/s and the k-ε turbulence model, suitable for high Reynolds number flows, with zero-gauge outlet pressure. This work further explores how boundary conditions, along with turbulence models and flow characteristics, play a role in the development of flow, from uniform velocity to fully developed turbulent flow. The results showed that the increase in bend angle resulted in the stability of flow, reducing the variation in velocity magnitude near the wall. A bigger radius of curvature in 120° and 150° bends reduced flow separation, which caused the uniformity in the velocity distribution. Provide insights for improvements in flow systems in energy-efficient HVAC applications. Maximum velocity comparison shows distinct characteristics of flow, the velocity at 90° is 21.05% higher than 120° and 11.87% higher than 150°, while the velocity at 150° is 8.23% higher than that at 120°. So, the order of magnitude of velocities is as follows, 90° has the maximum value, followed by 150°, and 120° has the minimum value. The analysis further showed that the pressure difference for a 90° bend is 466.2 Pa, exceeding the pressure difference at 120° by 105.7 Pa and that at 150° by 38.9 Pa. Correspondingly, its percentage difference is the highest at 90°, amounting to 279.64%. The pressure difference of 150° outshines 120° by 66.8 Pa, but its percentage difference remains a minimum and amounts to 145.3%. Overall, 90° presented the maximum value of pressure and percentage difference, followed by 150°, and then 120°.