Numerical simulation and experimental investigation of heat transfer and flow structures around heated spherical bluff bodies

A H Abed,S E Shcheklein,V M Pakhaluev

doi:10.1088/1742-6596/1333/3/032002

Abstract

The objective of this work is to evaluate the influence of vortices on heat transfer behaviour and a flow structure around a heated sphere. Numerical simulation and experimental verification are performed using a stationary copper sphere located inside a cylindrical channel with a constant channel-to-sphere diameter ratio. Numerical simulation is done for three-dimensional steady-state flow using ANSYS-FLUENT by solving the Reynolds-averaged Navier Stokes (RANS) equations. Over the test range of Reynolds numbers (2500-55000), CFD simulation results are in reasonable agreement with experimental data. The importance of vortices on heat transfer behaviour was investigated by taking the surface temperature and heat transfer coefficient (HTC) measurements around the sphere surface as a function of a zenith angle. The CFD simulation results confirmed that the impact of vortices on heat transfer behavior occurred in a lower-rear area of the sphere with a zenith angle (from 120° to 180°).

Highlights

The heat transfer and flow characteristics around heated spherical bluff bodies are one of actively and widely researched problems due to their notable importance in many engineering applications such as nuclear power plants, food and chemical processing, towed sonar system and so on
The importance of vortices on heat transfer behaviour was investigated by taking the surface temperature and heat transfer coefficient (HTC) measurements around the sphere surface as a function of a zenith angle
The comparison between CFD simulation and experiment of average surface temperature and heat transfer coefficient for a range of Re numbers are depicted in figures 2 and 3

Summary

Introduction

The heat transfer and flow characteristics around heated spherical bluff bodies are one of actively and widely researched problems due to their notable importance in many engineering applications such as nuclear power plants, food and chemical processing, towed sonar system and so on. Tsutsui and Okamoto [1,2] experimentally investigated the flow characteristics and the aerodynamic forces over a sphere located inside a wind tunnel under varying sphere heights above a turbulent boundary layer and noted the wake flow pattern around a sphere. Hassanzadeh et al [4] numerically investigated the flow configuration around a sphere as well as location of the stagnation-point and size of the wake length for Re = 5000. They noted that at a small-gap ratio, the flow pattern becomes symmetric and the reattachment point of flow occurs earlier. In the heat transfer field, the convective heat transfer downstream of bluff bodies depends on the many complex factors such as trailing vortices

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