通道内非对称布置纵向涡发生器强化换热分析

发布时间：2018-04-10 03:32

本文选题：非对称布置　切入点：纵向涡发生器　出处：《河北工业大学》2014年硕士论文

【摘要】：纵向涡发生器是一种有效的被动式强化传热方式。为进一步提高纵向涡发生器的强化传热效果,本文采用数值模拟的方法研究了纵向涡发生器的布置方式对矩形通道和圆形通道内的流动与换热的影响规律,得到的主要结论如下:对于矩形通道,Re的取值范围为500~2000,分析矩形翼纵向涡发生器对称与非对称布置时的流动与换热特性,结果表明:非对称布置纵向涡发生器比对称布置纵向涡发生器的Nu数减少4%~6%,但阻力因子f减少11%~22%。非对称布置纵向涡发生器的综合换热性能η比对称布置方式增加了5%~20%,表明非对称布置纵向涡发生器的综合换热性能更好。同时,对不同尺寸矩形翼对对称布置模型的翼间距、翼高、翼长、攻角等进行优化设计。对于圆管翅片换热器,Re的取值范围为500~2500,分析矩形翼纵向涡发生器对称与非对称布置时的流动与换热特性,结果发现:纵向涡发生器对圆管后侧的换热起到了增强作用,使圆管后侧的尾迹区明显减少,改善了换热最差的区域的换热。非对称布置纵向涡发生器比对称布置的Nu数仅减少2.6%~6.3%,阻力因子f减少了2.8%~18%,综合换热性能η提高2.4%~13%。利用大涡模拟方法研究了矩形通道内布置相同尺寸矩形翼对对称布置、不同尺寸矩形翼对对称布置、单个矩形翼交替等三种布置方式对流动与换热特性的影响。结果发现:当流体进入通道后,在纵向涡发生器的尾部会形成纵向涡旋,这些纵向涡旋在流动方向上不断的产生、发展和消亡,并且对加热面形成冲扫作用。对比涡量图、断面温度分布图和断面压力分布图得出,纵向涡发生器诱导的纵向涡使近壁面处的温度梯度发生变化,压力变化明显的地方主要集中在纵向涡集中的区域。
[Abstract]:Longitudinal vortex generator is an effective passive heat transfer enhancement method.In order to further improve the heat transfer enhancement effect of longitudinal vortex generator, the effect of the arrangement of longitudinal vortex generator on the flow and heat transfer in rectangular and circular channels is studied by numerical simulation.The main conclusions are as follows: the flow and heat transfer characteristics of rectangular wing longitudinal vortex generator under symmetrical and asymmetric arrangement are analyzed for the rectangular channel with a range of 500 ~ 2000 re.The results show that the number of Nu in the asymmetrical arrangement of longitudinal vortex generators is reduced by 4 and 6, but the resistance factor f is reduced by 11 and 22.The comprehensive heat transfer performance 畏 of asymmetric arrangement longitudinal vortex generator is increased by 5% 20% than that of symmetrical arrangement mode, which indicates that asymmetric arrangement longitudinal vortex generator has better comprehensive heat transfer performance.At the same time, the space, height, length and angle of attack of the symmetrical arrangement model of rectangular wing with different sizes are optimized.For the tube finned heat exchanger, the value range of re is 500 ~ 2500. The flow and heat transfer characteristics of rectangular wing longitudinal vortex generator are analyzed when it is symmetrical and asymmetric. The results show that the longitudinal vortex generator enhances the heat transfer at the back of the tube.The wake area at the back of the tube is reduced obviously, and the heat transfer in the worst heat transfer region is improved.Compared with the symmetrical arrangement, the number of Nu in asymmetrical vertical vortex generator is only reduced by 2.6% and 6.3%, the resistance factor f is reduced by 2.8%, and the integral heat transfer performance 畏 is increased by 2.4% and 13% respectively.The effects of the same size rectangular wing pair symmetrical arrangement, different size rectangular wing pair symmetrical arrangement and single rectangular wing alternate arrangement on the flow and heat transfer characteristics in rectangular channel are studied by using large eddy simulation method.The results show that when the fluid enters the channel, the longitudinal vortex will form in the tail of the longitudinal vortex generator, which will produce, develop and die out in the flow direction, and form a scouring effect on the heating surface.Compared with vorticity diagram, cross-section temperature distribution diagram and cross-section pressure distribution diagram, it is concluded that longitudinal vortex induced by longitudinal vortex generator changes the temperature gradient near the wall, and the pressure change is mainly concentrated in the region of longitudinal vortex concentration.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK124

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