Effect of orifice thickness-to-diameter ratio on turbulent orifice flow: An experimental and numerical investigation.

This paper reports a study on the effect of orifice thickness-to-diameter ratio (τ / d) on the turbulent flow through an orifice plate. Details of the flow characteristics downstream of the orifice are investigated both experimentally and numerically for a Reynolds number of 25,000. For this purpose, seven orifice plates are manufactured with τ / d ranging between 0.27 and 1.37. Particle Image Velocimetry (PIV) is used to experimentally study the flow patterns downstream of the orifices, with particular focus on instantaneous and time-averaged velocity distributions, streamline patterns, turbulent kinetic energy, Reynolds shear stress, and out-of-plane vorticity. Results show that, with increasing τ / d , the location of the vena contracta moves closer to the orifice plate, and eventually inside for τ / d > 0.55. Increasing τ / d also results in decreasing turbulent kinetic energy and Reynolds shear stress. For the selected τ / d range, experimental and numerical results are in good agreement with the thick and thin orifice classification available in the literature. • Effect of orifice thickness-to-diameter ratio, τ/ d on flow structures is studied. • Quantitative visualization of details of the orifice flow characteristics of hydrodynamics is reported. • As orifice thickness-to-diameter ratioincreases, decreasing velocity gradients and turbulence intensity are observed. • The minimum pressure downstream of the orifice is increased with increasing τ/ d , reached a peak value at τ/ d = 0.55 [ABSTRACT FROM AUTHOR]