The role of turbulence length scale and turbulence intensity on forced convection from a heated horizontal circular cylinder

The effects of turbulence integral length scale and turbulence intensity on the convective heat transfer rate from a heated circular cylinder in crossflow of air were investigated. An aluminium cylinder of diameter 50.8 cm (2″) and with uniform surface temperature was placed horizontally in a wind tunnel. The cylinder was subjected to a homogeneous, isotropic turbulent flow, which was generated using a perforated plate. The cylinder surface temperature was monitored and measured with five embedded thermocouples. Tests were conducted at a Reynolds number of 27,700, relative turbulence intensity, Tu from 2.9% to 8.3% and turbulence integral length scale to cylinder diameter ratio, L/D from 0.50 to 1.47. For L/D = 0.78, heat transfer increased with increasing turbulence intensity, whereas for Tu = 6.9%, heat transfer decreased with increasing turbulence length scale.