Enhancing Heat Transfer in Rectangular Channels: An Experimental Study on Perforated Concave Delta Winglet Vortex Generators

The inherent high thermal resistance of air impedes the heat transfer rate from tube surfaces to airflow within channels. This study aims to mitigate this issue by deploying perforated convex delta winglet pairs as vortex generators (VGs), strategically arranged in-line to reduce thermal resistance. Experimentation involved the installation of these vortex generators within the test section of a rectangular channel. Both convex delta winglet and perforated convex delta winglet pairs were mounted onto a flat plate in configurations of one, two, and three pairs. Airflow velocity within the channel was varied from 0.4 to 2.0 m/s at intervals of 0.2 m/s. Findings demonstrate an increase in the Nusselt number ratio by 1.5 and a 1.4 increment in the friction factor ratio with the utilization of three-row convex delta winglet pairs (CxDWPs) VGs at a Reynolds number of 8,724. Consequently, the thermal-hydraulic performance (TEF) approached a value of nearly 1.3 through the application of convex delta winglet vortex generators. This enhancement signifies the efficacy of convex delta winglets in augmenting heat transfer, thus addressing the challenge posed by air's thermal resistance.