Analysis of Pseudo-Turbulence Flow Induced by Bubble Periodic Formation in Non-Newtonian Fluids

Laser Doppler Velocimetry (LDV) has been employed to determine pseudo-turbulence characteristics of the flow field around bubble train forming in non-Newtonian caboxymethylcellulose (CMC) aqueous solution at low gas flow rate condition. The Reynolds stress and turbulent intensity of the liquid were investigated by means of Reynolds time-averaged method. The experimental results show that axial Reynolds stress rises greatly and then fluctuates slightly with the vertical height, whereas displays symmetrical Gaussian distribution in the horizontal direction; Radial Reynolds stress changes nonobviously in the vertical direction, but increases followed by a decrease in the horizontal direction. The axial turbulent intensity begins to wave to some degree with the height for near vertical axis passing through orifice center, but maintains constant within bubble channel in the horizontal direction; Radial turbulent intensity gets down with the vertical height, compared with the opposite trend of its variation with the horizontal distance.

کلیدواژه ها:

Non-Newtonian fluid ، Bubble train ، Laser Doppler velocimetry ، Pseudo-turbulence