Flow Past Permeable Manipulator Ring Placed in a Turbulent Pipe Flow (1st Report, Mean Flow Field)

The flow past the ring-type manipulator with permeability was investigated by measuring the mean flow field. The manipulator used in this study has a rectangular cross section with a height of 0.14 times the pipe radius. Main parameter was the ring open-area ratio (/9) with values of ,0.,0 .,0.3 and 0.4. The experiments were conducted for Reynolds number of Re =4 x104 to 10 x 104. The results indicate that as the ring open-area raito is increased, the separated shear layer arising from the ring top becomes weaker and the pressure loss reduces by increasing fluid flow through the manipulator ring. The critical ranges of )3 were identified, which provides useful references of engineering applications. When 13 is less than 0.2, the velocity gradient is steeper over the ring and in the shear layer near the reattachment region. When g is greater than 0.3, the width of the shear layer shows a relatively large augmentation and the back pressure in the separating region increases. There is no re-circulation flow behind the manipulator ring due to the large bleed flow through it in the case of 8=0.4.