Visual Experimental Investigations on Single-Phase Flow in Narrow Rectangular Channel with Longitudinal Vortex

Four pairs of rectangular blocks as longitudinal vortex generators（LVG） were mounted periodically in a narrow rectangular channel.To investigate the fluid flow structure in the channel,PDPA was employed to visually measure the single-phase velocity distribution.The velocity distribution of laminar and turbulent regime indicates that the longitudinal vortex will produce in the shape of secondary flow when the flow pass LVG,the development of flow boundary layer is restrained or broken,and the flow convective motion will be strengthened in the channel,so the heat transfer in the channel can be enhanced.This experiment reveals the qualitative physical mechanism of heat transfer enhancement in the narrow rectangular channel with longitudinal vortex.