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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

The Effect of Pulses Frequency on Flow and Heat Transfer due to Intermittent Impinging Mist Jets

Get access (open in a dialog) DOI: 10.1615/IHTC15.tps.008593
pages 9025-9035

Abstract

The flow structure and heat transfer of an intermittent impinging mist jet are numerically studied (with low mass concentration of droplets not more than l%).It is shown that both an increase and a suppression of heat transfer are characteristic of such a flow in comparison with the steady-state impinging gas-droplet jet. It is also shown that an increase in pulse frequency intensifies heat transfer initially in comparison with a steady-state jet; then, for higher frequencies heat transfer reduction is characteristic. An increase in the Reynolds number reduces heat transfer intensification, and data show that distribution of the Nusselt number for all frequencies approaches the single-phase flow regime. In the range of distances between the tube edge and target H/(2R) < 6 heat transfer at stagnation point increases with a rise of pulsation frequency, whereas at high distances H/(2R) > 8 frequency rise causes heat transfer reduction. Heat transfer intensity during flow pulse action increases and significantly exceeds the corresponding value for the steady-state case. When there is no flow, the value of the Nusselt number decreases considerably. Results obtained are compared with data from other authors, and satisfactory agreement is obtained for the influence of pulsation frequency on the heat transfer of a gas jet with impinging surface.