Mean Separation and Reattachment in Turbulent Pipe Flow Due to an Orifice Plate

The mean flow in a pipe with turbulent separated flow due to an orifice plate is experimentally studied. Measurements of time-mean length of separation and reattachment regions, made using a surface fence gauge are presented for a range of orifice sizes. In a limited range of Reynolds number (based on orifice radial height) 3 [times] 10[sup 4] to 7.3 [times] 10[sup 4] studied, reattachment point location decreased from 12 to 9 step heights. The lengths of separation and reattachment regions are a function of orifice size and the Reynolds number based on the radial height of the orifice plate.