Flow through a Pipe Orifice and its Loss Characteristiｃｓ

The flow through several kinds of orifices set in the circular pipeline and the loss characteristics due to their orifices were studied bythe numerical analysis in low Reynolds number and k -εmodel simulation in high Reynolds number. It was found that the present result agreed well with others' numerical and experimental ones. Besides. the main findings obtained in the present analyses are as follows. (1) In the low Reynolds number region (Re = 0 - 60). the flow through a pipe orifice and its loss are dependent on Reynolds number of pipe flow and the area ratio and the profile of orifice. In particular, the loss coefficients of orifices decrease in the tum of square, sharp and reverse - edged ones. provided fixed Reynolds number and the area ratio. (2) In the high Reynolds number region (Re = 2 x 104 -8 x 104 )，the loss coecient of square -edged orificeis independent of Reynolds number and depends on the area ratio and the thickness of orifice. It decreases with an increase of the relative thickness (t/D) in the range of t/D = 0.05ー0.20，if fixed the area ratio