Structure of the Boundary Layers on a Circular Cylinder in the Presence of Freestream Turbulence

An investigation of the influence of freestream turbulence on the temperature and velocity boundary layers on a circular cylinder in cross flow is presented. The investigation has been carried out for the two Reynolds numbers 5·104 and 1·105 with freestream turbulence intensities ranging from 2.5 – 11.5 % and integral scales Λf∞/D ≲ 0.14. Both experiments and numerical calculations show that for the flow ranges considered, the mean velocity field is rather unaffected by the freestream turbulence while the mean temperature field is influenced in such a way that increases in heat transfer of order 8 – 1 10 % occur.