Effect of modified expansion pipe nozzle on heat transfer enhancement with impinging jet
Keywords:impinging jet, expansion pipe nozzle, air entrainment, heat transfer enhancement
The aim of this study is to experimentally and numerically investigate the flow and heat transfer characteristics of impinging jet from expansion pipe with some modifications. The expansion pipe without air entrainment hole, with 4 and 8 air entrainment holes and hollow expansion pipe were connected to pipe nozzle and assessed to obtain the condition of heat transfer augmentation. The results from cases with expansion pipe were compared with cases of conventional pipe (without expansion pipe). In this study, the inner diameters of main pipe and expansion pipe were d=17.2 mm and D=68.8 mm (i.e., D=4d), respectively. The jet-to-plate distance (the distance from main pipe outlet to impingement surface) was varied at H=4d, 6d and 8d. The length of expansion pipe was fixed at L=2d, 4d and 6d. The comparison of all results was based on constant jet mass flow rate with Reynolds number of jet from the main pipe nozzle at Re=20,000. An infrared camera was used to measure the temperature distribution on the impingement surface, and the measured data were subsequently evaluated to gain Nusselt number distributions on the surface. The 3-D numerical simulation with SST k-ω turbulence model was carried out to investigate the flow field. The results show that the amount of ambient air entrained to the hollow expansion pipe is larger than the case of expansion pipe with air entrainment holes. Consequently, the heat transfer on the impingement surface for the case of hollow expansion pipe can be enhanced massively, especially for case of L=2d at H=4d.
Ashforth-Frost, S., & Jambunathan, K. (1996). Effect of nozzle geometry and semi-confinement on the potential core of a turbulent axisymmetric free jet. International Communications in Heat and Mass Transfer, 23(2), 155-162. DOI:10.1016/0735-1933(96)00001-2
Ashforth-Frost, S., Jambunathan, K., & Whitney, C. F. (1997). Velocity and turbulence characteristics of a semi confined orthogonally impinging slot jet. Experimental. Thermal and Fluid Science, 14(1), 60-67. DOI:10.1016/S0894-1777(96)00112-4
Baughn, J. W., & Shimizu, S. (1989). Heat transfer measurements from a surface with uniform heat flux and an impinging jet. Journal of Heat Transfer, 111(4), 1096-1098. DOI:10.1115/1.3250776
Gao, N., Sun, H., & Ewing, D. (2003). Heat transfer to impinging round jets with triangular tabs. International Journal of Heat and Mass Transfer, 46(14), 2557-2569. DOI:10.1016/S0017-9310(03)00034-6
Gulati, P., Katti, V., & Prabhu, S. V. (2009). Influence of the shape of the nozzle on local heat transfer distribution between smooth flat surface and impinging air jet. International Journal of Thermal Sciences, 48(3), 602-617. DOI:10.1016/j.ijthermalsci.2008.05.002
Hasan, M. A. Z., & Hussain, A. K. M. F. (1982). The self-excited axisymmetric jet. Journal of Fluid Mechanics, 115(2), 59-89. DOI:10.1017/S0022112082000652
Heo, M-W., Lee. K.-D., & Kim, K.-Y. (2011). Optimization of an inclined elliptic impinging jet with cross flow for enhancing heat transfer. Heat and Mass Transfer, 47(6), 731-742. DOI:10.1007/s00231-011-0763-2
Martin, R. H., & Buchlin, J. M. (2011). Jet impingement heat transfer from lobed nozzles. International Journal of Thermal Sciences, 50(7), 1199-1206. DOI:10.1016/j.ijthermalsci.2011.02.017
Huang, L., & El-Genk, M. S., (1998). Heat transfer and flow visualization experiments of swirling, multi-channel, and conventional impinging jets, International Journal of Heat and Mass Transfer, 41(3), 583-600. DOI:10.1016/S0017-9310(97)00123-3
Katti, V., & Prabhu, S. V. (2008). Influence of spanwise pitch on local heat transfer distribution for in-line arrays of circular jets with spent air flow in two opposite directions. Experimental Thermal and Fluid Science, 33(1), 84-95. DOI: 10.1016/j.expthermflusci.2008.07.004
Katti, V., & Prabhu, S. V. (2009). Influence of streamwise pitch on the local heat transfer characteristics for in-line arrays of circular jets with crossflow of spent air in one direction. Heat and Mass Transfer, 45(9), 1167-1184. DOI: 10.1007/s00231-009-0491-z
Kline, S. J., & McClintock, F. A. (1953). Describing uncertainties in single-example experiments. Mechanical Engineering, 75(1), 3-8.
Lytle, D., & Webb, B. W. (1994). Air jet impingement heat transfer at low nozzle-plate spacings. Intrnational Journal of Heat and Mass Transfer, 37(12), 1687-1697. DOI:10.1016/0017-9310(94)90059-0
Nathan, G. J., Hill, S. J., & Luxton, R. E. (1998). An axisymmetric ‘fluidic’ nozzle to generate jet precession. Journal of Fluid Mechanics. 370(1), 347-380. DOI:10.1017/S002211209800202X
Nathan, G. J., Alwahabi, M. J., Newbold, Z. T., & Nobes, D. S. (2006). Impacts of a jet’s exit flow pattern on mixing and combustion performance. Progress in Energy and Combustion Science. 32(5-6), 496-538. DOI:10.1016/j.pecs.2006.07.002
Nuntadusit, C., Wae-hayee, M., Bunyajitradulya, A., & Eiamsa-ard, S. (2012). Heat transfer enhancement by multiple swirling impinging jets with twisted-tape swirl generators. International Communications in Heat and Mass Transfer, 39(1), 102-107. DOI:10.1016/j.icheatmasstransfer.2011.10.003
Rohlfs, W., Haustein, H. D., Garbrecht, O., & Kneer, R. (2012). Insights into the local heat transfer of a submerged impinging jet: influence of local flow acceleration and vortex-wall interaction. International Journal of Heat and Mass Transfer, 55(25-26), 7728-7736. DOI:10.1016/j.ijheatmasstransfer.2012.07.081
Salim, S. M., Ariff, M., & Cheah, S. C. (2010). Wall y+ strategy for dealing with wall-bounded turbulent flows, Progress in Computational Fluid Dynamics. 10(5-6), 341-351.
Selerowicz, W. C., Szumowski, A. P., & Meier, G. E. A. (1991). Self-excited compressible flow in a pipe-collar nozzle. Journal of Fluid Mechanics, 228(7), 465-485. DOI: 10.1017/S0022112091002781
Viskanta, R. (1993). Heat transfer to impinging isothermal gas and flame jets. Experimental Thermal and Fluid Science, 6(2), 111-134. DOI:10.1016/0894-1777(93)90022-B
Wae-Hayee, M., Tekasakul, P., Eiamsa-ard, S., & Nuntadusit, C. (2015). Flow and heat transfer characteristics of in-line impinging jets with cross-flow at short jet-to-plate distance. Experimental Heat Transfer, 28(6), 511-530. DOI:10.1080/08916152.2014.913091
Zhou, D. W., & Lee, S.-J. (2004). Heat transfer enhancement of impinging jets using mesh screens. International Journal of Heat and Mass Transfer, 47(10-11), 2097-2108. DOI:10.1016/j.ijheatmasstransfer.2003.12.002
Zuckerman, N., & Lior, N. (2006). Jet impingement heat transfer: physics, correlations, numerical modeling. Advances in Heat Transfer, 39, 565-631. DOI:10.1016/S0065-2717(06)39006-5
Zeng, Y., New, T. H., & Tsai, H. M. (2009). On the use of notched collars on an axisymmetric jet. Experimental Thermal and Fluid Science, 33(6), 1029-1034. DOI:10.1016/j.expthermflusci.2009.04.006
Zeng, Y., New, T. H., & Chng, T. L. (2011). Flow behavior of turbulent nozzle jets issuing from beveled collars. Experimental Thermal and Fluid Science, 35(8), 1555-1564. DOI:10.1016/j.expthermflusci.2011.07.007
How to Cite
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.