Heat Transfer Enhancement of Jet Impingement on a Flat Plate Attached by a Porous Medium with a Center Cavity

Abstract:

Jet impingement heat transfer on a target plate covered with a thick porous layer with or without a cylindrical center cavity is experimentally investigated using the transient liquid crystal technique. Based on the results of jet impingement on a bare flat plate, heat transfer enhancement due to the attachment of porous medium is assessed. The varying parameters in the experiments include the nozzle-to-plate distance, jet Reynolds number, jet-to-cavity diameter ratio, and the cavity depth. Results of Nusselt number distribution, stagnation-zone Nusselt number, and averaged Nusselt number over a region of 3 times the hole diameter are documented. Experimental results show that the attachment of the porous layer with a center cavity can either hamper, or effectively enhance the jet impingement heat transfer over a flat plate. The maximum enhancement occurs at jet Reynolds number of 12400 when the cavity is a through hole and the cavity has the same diameter as the jet. The stagnation-zone Nusselt number increases 58.3% and the averaged Nusselt number increases 77.5% at the maximum enhancement condition. On the other hand, the addition of the thick porous layer without a center cavity gave rise to severe adverse effect on jet impingement heat transfer.

• Periodical: Defect and Diffusion Forum (Volumes 297-301)
• Pages: 427-432
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.297-301.427
• Online since: April 2010
• Authors: Pey Shey Wu, Chia Yu Hsieh, Shen Ta Tsai
• Keywords: Center Cavity, Heat Transfer Enhancement, Jet Impingement, Liquid Crystal Technique, Porous Medium

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[1] 1 17900 2 FP 99. 0 53. 2.

[2] 1 12400 2 FP 81. 4 42. 3.

[3] 1 8500 2 FP 60. 9 29. 8.

[4] 1 17900 6 FP 105. 6 45. 6.

[5] 1 12400 6 FP 63. 7 26. 7.

[6] 1 8500 6 FP 47. 0 19. 7.

[7] 1 17900 6 0 19. 8 19. 3.

[8] 1 12400 6 0 19. 5 19. 0.

[9] 1 8500 6 0 13. 1 12. 5.

[10] 1 17900 6 0. 8 118. 8 44. 9.

[11] 1 12400 6 0. 8 80. 4 42. 4.

[12] 1 8500 6 0. 8 57. 1 29. 6.

[13] 1 17900 8 0. 8 119. 9 50. 5.

[14] 1 17900 10 0. 8 71. 5 33. 7.

[15] 0. 5 17900 6 0. 8 21. 7 11. 1.

[16] 2 17900 6 0. 8 96. 4 54. 7.

[17] 1 17900 6 1 110. 6 58. 4.

[18] 1 12400 6 1 128. 8 75. 1.

[19] 1 8500 6 1 86. 8 48. 1 r/dh 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 0 �u.

[20] [40] [60] [80] 100 120 140 160 0. 5.

[1] [2] dj/dh Figure 8 - Effect of jet-to-cavity diameter ratio (Re = 17900, H/dh = 6).