MEAN VELOCITY AND TURBULENCE FIELDS INSIDE A BETA= 0.50 ORIFICE FLOWMETER

The flow field inside an orifice flowmeter with a beta ratio of 0.50 o perating at a Reynolds number of 91, 100 has been studied using a thre e-color, 3-D laser Doppler anemometer system. Mean velocity measuremen ts show large radial velocities leading into the orifice, the fluid se parating from the orifice plate at the throat, the presence of a vena contracta farther downstream, flow reattachment to the pipe wall 5.3 p ipe radii (R) downstream, the presence of a small upstream recirculati on zone, and both a primary and secondary recirculation zone downstrea m of the orifice plate. The static wall pressure distribution attains a minimum pressure at 1.5 R, which does not coincide with the location of the vena contracta (0.75 R). Distributions of the entire Reynolds stress tensor are presented along with calculated values of turbulence kinetic energy, turbulence kinetic energy production, vorticity, and turbulence induced accelerations. These data are analyzed to interpret the complex turbulent flow field.