HEAT-TRANSFER AND ASSOCIATED ENERGY-DISSIPATION FOR OSCILLATORY FLOW IN BAFFLED TUBES

We report experimental data on the heat transfer performance of a periodically baffled tube subject to both steady (net) flow and oscillatory flow. The data show that, in particular, at a low net flow Reynolds number, significant heat transfer enhancement can be achieved with the superposition of fluid oscillations. A general correlation is derived for the measured Nusselt number as a function of both net flow and oscillatory Reynolds number. Dynamic pressure drop data for oscillatory Bow are also reported, and estimates of energy efficiency for obtaining heat transfer enhancement made from these measurements are compared with smooth wall turbulent how equations. For large amplitudes of oscillation (equivalent to half the tube diameter) the overall power dissipation follows the quasi-steady theory. At smaller amplitudes of oscillation the power dissipation was larger than predicted by the quasi-steady theory, indicating an increased eddy interaction.