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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EXPERIMENTAL INVESTIGATION OF IMPINGING HEAT TRANSFER OF PULSED JET ON CONCAVE PLATE

Get access (open in a dialog) DOI: 10.1615/IHTC16.hte.023030
pages 5275-5300

Sinopsis

Impinging jets can achieve a high local convective heat flux on heating or cooling surfaces, therefore, it has a potential application on various industrial equipment. The heat transfer of pulsation impinging jets on flat plate had been fully researched, yet the understanding of its mechanism on semi-cylindrical concave surface remained inadequate. In this study, experimental investigation was carried out to reveal the impinging heat transfer of pulsation jet on semi-cylindrical concave surface. Range of parameters include the Reynolds number of 5000 to 40000, operation frequency of 10 to 25Hz and spacing ratio H/d of 1 to 8. The temperature on the target plate was obtained by Infrared Cameras. Pulsation jet with constant operation frequency and duty cycle was generated by the solenoid valve. The result shows that at small spacing ratio H/d, circumferential differences of the Nusselt number distribution on the target plate is occurred because of chevron-shape of the nozzle; as the spacing ratio H/d increases, such circumferential differences gradually vanish. Nusselt number decreases with the operation frequency ƒ while increases with the increase of Reynold number Re. Pulsation jet has a heat transfer performance reduction compared with steady jet impinging on concave plate with the same Re and H/d. The Nusselt number by pulsation jet have a maximum decreasing of 21.0% (H/d=4, Re=20000) compared with that by steady jet. Comparison between flat plate and concave plate on pulsation jet were conducted with same operation parameters. The results indicate the flat plate has a better heat transfer performance over the concave surface, latter has a maximum reduction of 37.7% compared with that on flat plate with H/d=8, Re=5000. A Large Eddy Simulation(LES) was performed to illustrate its flow mechanism and to validate the heat transfer characteristic of pulsation jet.