Flow-induced vibration analysis of conical rings used for heat transfer enhancement in heat exchangers

In the present work, flow-induced vibration characteristics of conical-ring turbulators used for heat transfer enhancement in heat exchangers are investigated experimentally. The conical-rings, having 10, 20 and 30 mm pitches, are inserted in a model pipe-line through which air is passed as the working fluid. Vortex-shedding frequencies and amplitude are determined and St-Re. Prms-Re variations are presented graphically. Flow-acoustic coupling is also analyzed experimentally. It is observed that as the pitch increases, vortex shedding frequencies also increase and the maximum amplitudes of the vortices produced by conical-ring turbulators Occur with small pitches. In addition, the effects of the promoters on the heat transfer and friction factor are investigated experimentally for all the arrangements. It is found that the Nusselt number increases with the increasing Reynolds number and the maximum heat transfer is obtained for the smallest pitch arrangement. (C) 2003 Elsevier Ltd. All rights reserved.