標題: | A further investigation of effects of jet-disk separation distance on steady mixed convective vortex flow resulting from a confined impinging air jet |
作者: | Chen, K. M. Hsieh, F. C. Hsieh, J. C. Lin, T. F. 機械工程學系 Department of Mechanical Engineering |
關鍵字: | Impinging jet;Vortex flow;Jet-disk separation distance;Buoyancy effects |
公開日期: | 1-十一月-2009 |
摘要: | We extend our previous study [J.C. Hsieh, T.F. Lin, Effects of jet-to-disk separation distance on the characteristics of mixed convective vortex flow in an impinging air jet confined in a cylindrical chamber, Int.J. Heat Mass Transfer 48 (2005) 511-525] here to further investigate how the jet-disk separation distance H affects the mixed convective vortex flow resulting from a round air jet impinging onto a heated horizontal circular disk confined in a vertical cylindrical chamber. The experiment is conducted for the jet-disk separation distance varying from 40.0 to 60.0 mm and the jet flow rate is varied from 0 to 12.0 slpm (standard liter per minute) for the jet Reynolds number Re(j) ranging from 0 to 1623. The temperature difference between the disk and the air injected into the chamber is varied from 0 to 25.0 degrees C for the Rayleigh number Ra ranging from 0 to 507,348. The data from the present study for the ratio H/D(j) = 4-6 are compared with our previous study for H/D(j) = 1-3. The results indicate that the critical jet Reynolds numbers for the onsets of the secondary and tertiary inertia-driven rolls and for the onset of the buoyancy-driven roll vary nonmonotonically with the jet-disk separation distance due to the complicate changes of the vortex flow structure with H. In the steady vortex flow, both the primary inertia-driven roll and the buoyancy-driven roll get larger at increasing jet-disk separation distance before they contact with each other for H/D(j) = 1 and 2. But for H/D(j) >= 3 the primary roll and buoyancy roll do not always grow at increasing H. Finally, empirical correlations are proposed for the critical conditions leading to the onsets of the inertia- and buoyancy-driven vortex rolls. (C) 2009 Elsevier Ltd. All rights reserved. |
URI: | http://dx.doi.org/10.1016/j.ijheatmasstransfer.2009.07.009 http://hdl.handle.net/11536/6475 |
ISSN: | 0017-9310 |
DOI: | 10.1016/j.ijheatmasstransfer.2009.07.009 |
期刊: | INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER |
Volume: | 52 |
Issue: | 23-24 |
起始頁: | 5348 |
結束頁: | 5357 |
顯示於類別: | 期刊論文 |