An experimental and numerical study of turbulent swirling flow in gas cyclones

Experimental results on the turbulent, strongly swirling flow field in a re verse flow gas cyclone separator are presented, and used to evaluate the pe rformance of three turbulence closure models Mean and fluctuating velocity components were measured for gas cyclones with different geometric swirl nu mbers by means of laser-Doppler velocimetry. The experimental data show the strong effect of the geometric swirl number on mean flow characteristics, in particular with respect to vortex core size and the magnitude of the max imum tangential velocity. It is shown that the forced vortex region of the flow is dominated by the so-called precessing vortex core. Numerical calcul ation of the cyclonic flow shows that turbulence models based on the eddy-v iscosity approach fail to predict the combined vortex observed experimental ly. Predictions with the Reynolds stress transport model are in reasonable agreement with measured profiles for all three swirl numbers, though the tu rbulent normal stresses are generally overpredicted. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.