Vortex dynamics and heat transfer of longitudinal vortex generators in a rectangular channel. (April 2019)

• Record Type: Journal Article
• Authors: Ke, Zhaoqing; Chen, Chung-Lung; Li, Kuojiang; Wang, Sheng; Chen, Chien-Hua
• Is Part Of: International journal of heat and mass transfer. Volume 132(2019)
• Page Start: 871
• Page End: 885
• Publication Date: 2019-04
• Subjects: Longitudinal vortex generator -- Common flow down -- Common flow up -- Mixed configuration -- Heat transfer enhancement -- Method of images -- Vortex dynamics; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2018.12.064
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Method of images is successfully adopted to predict the LVG vortex dynamics. A mixed LVG configuration is suggested to enhance the heat transfer performance. LVG aspect ratio and channel height are very critical to the LVG effectiveness. Abstract: This paper reports a numerical investigation of fluid flow and heat transfer in a rectangular channel with delta-shaped winglet longitudinal vortex generators (LVGs) under different configurations. In addition to the conventional common-flow-down configuration and the common-flow-up configuration, a unique mixed configuration is suggested. The "method of images" is successfully adopted to analyze the dynamics of the longitudinal vortices due to wall interference. The Nusselt number, friction factor and overall performance coefficient for the three configurations are compared at various Reynolds numbers (all less than 2200), LVG row numbers, channel heights, and LVG aspect ratios. It is found that the channel height and LVG aspect ratio are the two most critical factors influencing the effectiveness of the different LVG configurations, which may explain why inconsistent conclusions have been presented by previous studies comparing the performance of the common-flow-down and common-flow-up configurations. When the channel height is relatively small, the unique mixed configuration is found to be the most effective at enhancing fluid mixing (and therefore improving heat transfer) at streamwise cross sections. When the LVG aspect ratio becomes large, the common-flow-down configuration outperforms the common-flow-up configuration. This paper sheds some insight on how to design the optimal LVG configuration for enhancing heat transfer performance.