A study of flow interference and heat transfer between two-cylinders at different orientations

Abstract

A numerical investigation is carried out for the different orientations of a circular cylinder where the upstream cylinder moves with varying angles α = 0˚, 30˚, 45˚, 60˚, 90˚ with respect to the downstream cylinder in a fixed position at a gap ratio (L/D) of 3 where L is the distance from centre to centre between cylinders and D is the diameter of the cylinder. Reynolds number (Re), is based on cylinder diameter, is kept constant at 200 for all the cases with air as the working medium. The vortex shedding formation is analysed when the vortices from the upwind cylinder interact with the downwind cylinder and give impressive flow patterns. It is observed that the drag and lift coefficients increase for both the cylinders with change in angular position. Strouhal number is calculated with the help of Fast Fourier transformation (FFT) of vorticity magnitude and evaluated for each case. It is observed that the effect of upwind cylinder on downwind cylinder is significant for α = 30˚, 45˚, 60˚ orientation cases and vortex shedding frequency increases for these cases. Further, the investigation is extending on the laminar forced convection heat transfer performance and variation of Nusselt number for the cylinders. Maximum heat transfer is observed for the downwind cylinder at α = 45˚. In contrast, the local Nusselt number does not vary much for the cylinders except for the downwind cylinder at α = 0˚.

Keywords

• Tandem cylinder
• Vortex shedding
• Nusselt number
• Strouhal number