矩形截面螺旋通道内流体绕管流动特性的数值研究
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摘要
基于Fluent软件采用数值计算方法建立了混合计算模型,对螺旋通道和直通道内流体绕换热管的换热特性进行研究,对比了2个通道中流体绕换热管流动的热工特性。结果表明:螺旋通道内侧脱点角度小于外侧脱点角度,且脱点均分布在湍流区域内;螺旋通道比直通道具有更高的Nu_m;β=15°和20°螺旋通道换热管壁面迎风侧Nu_m相比直通道分别提高4.0%和4.5%,背风侧则分别提高14%和18%;当螺旋角β=40°附近,螺旋通道达到最佳强化换热管壁面换热效果,螺旋通道内换热管壁面Nu_m相比直通道提高19%。
Using Fluent software and numerical calculation method, a hybrid calculation model was established to study the heat-transfer characteristics of fluid flow around the heat-exchange tube in a spiral channel and a straight channel, and to compare the thermal characteristics of fluid flow around a heat-exchange tube in above two channels. Results show that the inner detachment angle of spiral channel is smaller than outer detachment angle, and the detachment points are distributed in the turbulent region. The Nu_m of spiral channel is higher than that of straight channel; in the case of β=15° and 20°, compared with straight channel heat-exchange tube, the Nu_m of spiral channel heat-exchange tube is respectively 4.0% and 4.5% higher on the windward side, and 14% and 18% higher on the leeward side. Around β=40°, the heat-transfer performance is maximally enhanced for the tube in spiral channel, when the tube wall Nu_m is increased by 19%, compared with the straight channel.
Using Fluent software and numerical calculation method, a hybrid calculation model was established to study the heat-transfer characteristics of fluid flow around the heat-exchange tube in a spiral channel and a straight channel, and to compare the thermal characteristics of fluid flow around a heat-exchange tube in above two channels. Results show that the inner detachment angle of spiral channel is smaller than outer detachment angle, and the detachment points are distributed in the turbulent region. The Nu_m of spiral channel is higher than that of straight channel; in the case of β=15° and 20°, compared with straight channel heat-exchange tube, the Nu_m of spiral channel heat-exchange tube is respectively 4.0% and 4.5% higher on the windward side, and 14% and 18% higher on the leeward side. Around β=40°, the heat-transfer performance is maximally enhanced for the tube in spiral channel, when the tube wall Nu_m is increased by 19%, compared with the straight channel.
引文
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[3]KHALZOV I V,BROWN B P,EBRAHIMI F,et al.Numerical simulation of laminar plasma dynamos in a cylindrical von Krmn flow[J].Physics of Plasmas,2011,18(3):032110.
[4]CAPONE D E,LAUCHLE G C.Modelling the unsteady axial forces on a finite-length circular cylinder in cross-flow[J].Journal of Fluids and Structures,2002,16(5):667-683.
[5]PEYRIN F,KONDJOYAN A.Effect of turbulent integral length scale on heat transfer around a circular cylinder placed cross to an air flow[J].Experimental Thermal and Fluid Science,2002,26(5):455-460.
[6]WU Shuangying,CHEN Sujun,LI Yourong,et al.Numerical investigation of turbulent flow,heat transfer and entropy generation in a helical coiled tube with larger curvature ratio[J].Heat&Mass Transfer,2009,45(5):569-578.
[7]林清宇,刘鹏辉,冯振飞,等.螺旋通道内流体流动与传热特性研究进展[J].科学通报,2017,62(25):2931-2940.LIN Qingyu,LIU Penghui,FENG Zhenfei,et al.Areview on fluid flow and heat transfer in helical channel[J].Chinese Science Bulletin,2017,62(25):2931-2940.
[8]BOLINDER C J,SUNDN B.Numerical prediction of laminar flow and forced convective heat transfer in a helical square duct with a finite pitch[J].International Journal of Heat&Mass Transfer,1996,39(15):3101-3115.
[9]邢云绯,仲峰泉,张新宇.矩形横截面螺旋管湍流流动与传热特性的数值研究[J].航空学报,2013,34(6):1269-1276.XING Yunfei,ZHONG Fengquan,ZHANG Xinyu.Numerical study of turbulent flow and heat transfer characteristics in helical rectangular ducts[J].Acta Aeronautica et Astronautica Sinica,2013,34(6):1269-1276.
[10]赵文升,唐雪峰,李卫华.侧风下浮力驱动“塔烟”流动及换热特性数值研究[J].动力工程学报,2014,34(5):404-410.ZHAO Wensheng,TANG Xuefeng,LI Weihua.Flow and heat transfer characteristics in buoyancy driven"natural draft cooling tower"under crosswind conditions[J].Journal of Chinese Society of Power Engineering,2014,34(5):404-410.
[11]周云龙,张超,张立彦,等.矩形螺旋通道气液两相流流动和传热特性数值研究[J].化工机械,2016,43(3):357-364.ZHOU Yunlong,ZHANG Chao,ZHANG Liyan,et al.Numerical study of flow and heat transfer characteristics of gas-liquid flow in rectangular spiral channel[J].Chemical Engineering&Machinery,2016,43(3):357-364.
[12]肖姚,秦浩,宋文武,等.较大雷诺数下方柱绕流的数值模拟[J].动力工程学报,2017,37(8):679-684.XIAO Yao,QIN Hao,SONG Wenwu,et al.Numerical simulation of the flow around a square cylinder at higher Reynolds numbers[J].Journal of Chinese Society of Power Engineering,2017,37(8):679-684.
[13]张定才,何雅玲,刘启斌,等.内螺旋肋管流动与传热特性的实验研究[J].工程热物理学报,2006,27(6):1029-1031.ZHANG Dingcai,HE Yaling,LIU Qibin,et al.Experimental study of fluid flow and heat transfer in internal helical-rib tubes[J].Journal of Engineering Thermophysics,2006,27(6):1029-1031.
[14]陶文铨.数值传热学[M].2版.西安:西安交通大学,2001.
[15]由长福,祁海鹰,徐旭常,等.采用不同湍流模型及差分格式对四角切向燃烧煤粉锅炉内冷态流场的数值模拟[J].动力工程,2001,21(2):1128-1131.YOU Changfu,QI Haiying,XU Xuchang,et al.Numerical simulation of flow field in tangentially fired boiler using different turbulence models and discretization schemes[J].Power Engineering,2001,21(2):1128-1131.
[16]SCHOLTEN J W,MURRAY D B.Unsteady heat transfer and velocity of a cylinder in cross flow-I.Low freestream turbulence[J].International Journal of Heat and Mass Transfer,1998,41(10):1139-1148.
[17]SZCZEPANIK K,OOI A,AYE L,et al.A numerical study of heat transfer from a cylinder in cross flow[C]//15th Australasian Fluid Mechanics Conference.Sydney,Australia:The University of Sydney,2004.