Thermal and material transfer in turbulent gas streams: One‐inch spheres

Abstract

Abstract As part of a study of the effect of conditions of flow upon macroscopic and local thermal and material transport from spheres, an investigation was made of the macroscopic and local transport from a silver and a porous sphere each 1 in. in diameter. The transport was measured in a turbulent air stream at Reynolds numbers up to 7,500, and the apparent level of longitudinal turbulence of the stream was varied between 0.013 and 0.15. In the case of the porous sphere the thermal and material transport were evaluated for the evaporation of n ‐octane. The results indicate that the macroscopic Nusselt number is substantially larger for combined thermal and material transport than for thermal transport alone. The local Nusselt number varied by a factor of 5 around the silver sphere from stagnation to separation.