Transient CFD Analysis of Different Cross-Section Fins Under Free-Convection Conditions Lakshminarasimha. N 1 1 IGBC AP and Assistant Professor, Department of Mechanical Engineering, New Horizon College of Engineering, Bengaluru Dr. M. S. Rajagopal 2 2 Professor and Chairman, Department of Mechanical Engineering, Dayananda Sagar University, Bengaluru Abstract- Manufacturers of aerospace and defense equipments are presently facing challenges related to both steady state and transient reliability of electronics systems; the continuing reduction in size of electronic components is resulting in higher power density due to which thermal management of electronic components is critical in electronic product development. Among heat transfer augmentation technique, passive cooling technique is more suitable than active cooling for specific applications. Also providing fins can regulate the temperature of the system at optimum levels by providing extended surface area of contact with surrounding cooling medium- air. In the present work, the Transient analysis has been carried out for three different cases to determine the transient performance considering different cross-sectional fins such as Tapered, Round and Rectangular configurations. The fins are subjected to free-convection cooling which are placed on plate with four heat sources each dissipating 100W power. Transient analysis is carried out using ANSYS CFD software for time step of 20 seconds and results obtained for different cross-section are compared for optimum temperature levels. Keywords: Fins, Tapered fin, Round Fin, Rectangular Fin, Transient analysis, ANSYS CFD, Free-convection. 1. INTRODUCTION To increase the heat transfer rates by increasing the surface heat transfer coefficient or increasing the temperature difference between surface and surrounding medium sometimes becomes impossible at particular condition and application; hence at that situation fins can be used for increasing the heat transfer rates from the surfaces [17]. Fins are classified as straight fins with uniform (Fig. 1.1) and non-uniform thickness (Fig. 1.2), annular fins (Fig. 1.3) and spine of constant cross-section (Fig. 1.4) and non- uniform cross section (Fig. 1.5). Fig. 1.1 Fig. 1.2 Fig. 1.3 Fig. 1.4 Fig. 1.5 The knowledge of temperature distribution along the fin is necessary for proper design of fins. Hence in the present work, Transient analysis is carried out using ANSYS CFD for understanding the temperature distribution and heat flow from different cross-section fins such as Tapered, Round and Rectangular fins. 2. LITERATURE SURVEY Literature survey is carried out to understand the state of art in CFD transient analysis on natural convection cooling of fins. Here are some literatures as discussed below: Santosh Kansal et.al., [1], [2015], This paper deals with a comparative study using CFD on Electronic enclosure consisting fins of different configuration. The overall performance of the six different heat sinks with different shaped pin-fin structures was studied in this paper for different velocities varying from 5, 10 & 12 m/s. The paper presents simulation and thermal analysis of different shape fins heat sink for an electronic system cooled by natural convection. Aartee. S. Lokhande, [2], [2018], this article gives overall review on work carried out on Transient analysis fins with different shapes and briefs some of technical details on fins. Only major journals are discussed in this section, remaining journals, articles and textbooks listed in References. International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 http://www.ijert.org IJERTV8IS060478 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Published by : www.ijert.org Vol. 8 Issue 06, June-2019 807