ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
The Effect of Pulses Frequency on Flow and Heat Transfer due to Intermittent Impinging Mist Jets
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.