Turbulent Flow Through a Ducted Elbow and Plugged Tee Geometry: An Experimental and Numerical Study

Abstract

An experimental and computational comparison of the turbulent flow field for a sharp 90 deg elbow and plugged tee junction is presented. These are commonly used industrial geometries with the tee often retrofitted by plugging the straight exit to create an elbow. Mean and fluctuating velocities along the midplane were measured via two-dimensional (2D) particle image velocimetry (PIV), and the results were compared with the predictions of Reynolds-averaged Navier–Stokes (RANS) simulations for Reynolds numbers of 11,500 and 115,000. Major flow features of the elbow and plugged tee were compared using the mean velocity contours. Geometry effects and Reynolds number effects were studied by examining the mean and root-mean-square (RMS) fluctuating velocity profiles at six positions. Finally, the asymmetry of the flow as measured by the position of the centroid of the volumetric flux and pressure loss data were examined to quantify the streamwise evolution of the flow in the respective geometries. It was found that in both geometries there was a large recirculation zone in the downstream leg but the RANS simulations predicted an overly long recirculation which led to significantly different mean and fluctuating velocities in that region when compared to the experiments. Comparison of velocity profiles showed that both experiments and numerics agree in the fact that the turbulence intensities were greater at higher Re downstream of the vertical leg. Finally, it was shown that the plugged tee recovered its symmetry more rapidly and created less pressure loss than the elbow.

Overview on the hydrodynamic conditions found in industrial systems and its impact in (bio)fouling formation

“…In industrial facilities, all the fluids are distributed by hydraulic circuits, that have different components, such as pipes [65,83], sudden or abrupt contractions and expansions [55,110], elbows [111,112], flow meters and controllers [113,114], static mixers [115,116], tees, bends and pumps. Due to surface colonization by microorganisms, biofouling development in these systems is inevitable with more persistence in regions characterized by low hydrodynamics.…”

“…In fact, Simunic et al [44] verified that in dead-end zones, fouling was not affected by fluid flushing (high turbulence from high fluid velocity) that was typical for the main pipe. Several studies identified critical areas for fouling formation such as the regions closed to corners and baffles [59,75,104] and header section [102] in HE, regions closed to expansions/contractions [110,120], angles [128,134], elbows [112,133], and valves [12,114] in distribution networks, and regions closed to corners in the bottom [154], and baffles in the tank wall [165] in STRs. In addition of being prone for fouling phenomena, dead-end zones affect CIP efficacy, compromising the process and product quality, and increase operating and maintenance costs [12].…”

A Numerical Investigation of the Influence of Geometric Parameters on the Performance of a Multi-Channel Confluent Water Supply

“…The MCCS structure is a combined manifold consisting of several channel pipes, a clustered pipe and a main pipe. According to reference [7], a pugged tee junction creates less pressure loss than a sharp 90 degree elbow in a turbulent flow field. Therefore, the form of the channel pipe and clustered pipe is a T-connection.…”

“…The MCCS structure is composed of pipes and T-shaped tees. Andrew M. Bluestein presents the turbulent flow field for a sharp 90 degree elbow and a plugged, T-shaped junction by experiment and computation, and the conclusion shows that a pugged T-shaped structure creates less pressure loss than a sharp elbow [7]. It is mainly reasoned that the MCCS structure consists of a T-shaped rather than elbow-shaped.…”

“…In [14], the pressure losses of a 90 degree elbow were investigated by the two analyses, and the results show good agreement, and in [15], the pressure losses in 90 degree elbow considering the geometry were studied both with numerical analysis and experimental. In [7], the authors studied the pressure losses of the turbulent flow field for a sharp 90 degree elbow and a plugged tee junction by experiment and simulation.…”