Experimental study and large eddy simulation of turbulent flow around tube bundles composed of wavy and circular cylinders

Abstract

This paper presents the results of an investigation on the effects of wavy cylindrical tubes in a staggered heat exchanger tube bundle. Experimental measurements and large eddy simulation (LES) technique were used to study the turbulent flow characteristics in a staggered tube bundle arrangement at a sub-critical Reynolds number of Re = 7500. The aim of this investigation is to compare the flow characteristics of a new configuration of cylindrical tubes with that of a similar arrangement which comprises purely circular cylinders. The first row of circular tubes is replaced by a row of wavy cylindrical tubes. The result of the experiment shows that the mean velocity distributions and turbulence intensity, obtained by the present LES method, are in good agreement with the Laser Doppler Anemometer (LDA) measurements. The wake patterns around the second row of cylinders become more well organized upon the introduction of wavy cylinders of optimal wavelength (λ/Dm = 6). The turbulent kinetic energy behind the first row of tubes is also reduced. The power density spectra of the vortex shedding in the tube bundle are evidently suppressed. As a result, the fluctuating forces of the tube bundles are weakened. However, the drag is not noticeably reduced by such modification.