Flow and Heat Transfer Characteristics of Flow Past the Bluff Body in Turbulent Boundary Layer

doi:10.3901/JME.2015.24.168

Abstract

Abstract: The mechanism of heat transfer enhancement and flow drag reduction of small scale circular cylinder vortex generator with a slit is numerically investigated by large eddy simulation. The circular cylinder with a horizontal slit is located in the fully developed turbulent boundary layer. The influence of gap ratios on the circular cylinder wake, the coherent structure of turbulent boundary layer, flow and heat transfer characteristics of the channel bottom wall are probed. To validate the accuracy and reliability of the present numerical method, the results of the rectangular empty channel with present numerical method are compared with the results by direct numerical simulation and empirical correlation equation. The results show that the interaction between the wake flow of bluff body and the wall boundary layer can enhance prominently the overall thermal performance of the channel flow. Compared with the reference cylinder, the overall thermal performance is better when the gap ratio is less than 2.0, the synthetic coefficient reaches maximum when the gap ratio is 2.0, and the thermal performance is lower when the gap ratio is more than 2.0. Compared with the rectangular empty channel, the maximum Nusselt can be increased by 17.45%, the minimum frication coefficient can be decreased by 4.94%.

Key words: cylinder with slit, gap ratio, heat transfer enhancement, large eddy simulation, reference cylinder

WANG Jiansheng, WANG Xiao, ZHU Qiang, ZHAO Yunjian. Flow and Heat Transfer Characteristics of Flow Past the Bluff Body in Turbulent Boundary Layer[J]. Journal of Mechanical Engineering, 2015, 51(24): 168-176.

References

[1] KLINE S J，REYNOLDS W C，SCHRAUB F A，et al. The structure of turbulent boundary layers[J]. Journal of Fluid Mechanics，1967，30(4)：741-773.
[2] PRATURI A K，BRODKEY R S. A stereoscopic visual study of coherent structures in turbulent shear flow[J]. Journal of Fluid Mechanics，1978，89(2)：251-272.
[3] 高小明，李惟毅，汪健生. 湍流边界层内添加控制的流动与传热特性[J]. 中国电机工程学报，2013，33(14)：67-74.GAO Xiaoming，LI Weiyi，WANG Jiansheng. Flow and heat transfer characteristics of turbulent boundary layer with control[J]. Proceedings of the CSEE，2013，33(14)：67-74.
[4] 汪健生，汤俊杰，张金凤. 半椭圆涡流发生器强化换热机理[J]. 机械工程学报，2006，42(5)：160-164.WANG Jiansheng，TANG Junjie，ZHANG Jinfeng. Mechanism of heat transfer enhancement of semi-ellipse vortex generator[J]. Chinese Journal of Mechanical Engineering，2006，42(5)：160-164.
[5] 汪健生，刘志毅，张金凤，等. 斜截椭圆柱式涡流发生器强化传热的大涡模拟[J]. 机械工程学报，2007，43(10)：55-61.WANG Jiansheng，LIU Zhiyi，ZHANG Jinfeng，et al. Large eddy simulation on heat transfer enhancement of inclined-cut ellipsoidal vortex generator[J]. Chinese Journal of Mechanical Engineering，2007，43(10)：55-61.
[6] 叶秋玲，周国兵，程金明，等. 斜截半椭圆柱面涡流发生器强化换热和压降特性的试验研究[J]. 机械工程学报，2010，46(16)：162-169. YE Qiuling，ZHOU Guobing，CHENG Jinming，et al. Experimental study of heat transfer enhancement and pressure drop characteristics of oblique-cut semi-elliptic cylinder shell vortex generators[J]. Journal of Mechanical Engineering，2010，46(16)：162-169.
[7] CHOI H S，SUZUKI K. Large eddy simulation of turbulent flow and heat transfer in a channel with one wavy wall[J]. International Journal of Heat and Fluid Flow，2005，26(5)：681-694.
[8] 高小明，李惟毅，汪健生. 一种低流阻表面的流动与传热特性[J]. 机械工程学报，2012，48(8)：128-134.GAO Xiaoming，LI Weiyi，WANG Jiansheng. Flow and heat transfer characteristics of low flow resistance surface[J]. Journal of Mechanical Engineering，2012，48(8)：128-134.
[9] PRICE S J，SUMNER D，SMITH J G，et al. Flow visualization around a circular cylinder near to a plane wall[J]. Journal of Fluids and Structures，2002，16 (2)：175-191.
[10] WANG X K，TAN S K. Comparison of flow patterns in the near wake of a circular cylinder and a square cylinder placed near a plane wall[J]. Ocean Engineering，2008，35(5-6)：458-472.
[11] SARKAR S，SARKAR S. Vortex dynamics of a cylinder wake in proximity to a wall[J]. Journal of Fluids and Structures，2010，26(1)：19-40.
[12] IGARASHI T. Flow characteristics around a circular cylinder with a slit：Flow control and flow patterns[J]. Bulletin of the JSME，1978，21(154)：656-664.
[13] OLSEN J F，RAJAGOPALAN. Vortex shedding behind modified circular cylinders[J]. Journal of Wind Engineering and Industrial Aerodynamics，2000，86(1)：55-63.
[14] BAEK H，KARNIADAKAIS G E. Suppressing vortex-induced vibrations via passive means[J]. Journal of Fluids and Structures，2009，25(5)：848-866.
[15] KIM J，MOIN P，MOSER R. Turbulence statistics in fully developed channel flow at low Reynolds number[J]. Journal of Fluid Mechanics，1987，177：133-166.
[16] MANSOUR N N，KIM J，MOIN P. Reynolds-stress and dissipation budgets in a turbulent channel flow[J]. Journal of Fluid Mechanics，1988，194：15-44.
[17] INCROPERA F P，DEWITT D P. Fundamentals of heat and mass transfer[M]. New York：John Wiley & Sons Inc.，1996.
[18] DECK S，WEISS P E，PAMIES M. Zonal detached eddy simulation of a spatially developing flat plate turbulent boundary layer[J]. Computers & Fluids，2011，48(1)：1-15.
[19] ZHOU J，ZHONG S. Coherent structures produced by the interaction between synthetic jets and a laminar boundary layer and their surface shear stress patterns[J]. Computers & Fluids，2011，39(8)：1296-1313.