Local and macroscopic thermal transport from a sphere in a turbulent air stream

Abstract

AbstractThe local and macroscopic thermal transport from a calorimeter‐instrumented sphere 1.5 in. in diameter located in an air steram ws measured experimentally in the subcritical flow regime. The Reynolds number was varied between 5,200 and 70,200 with artificially induced turbulence level varying from 0.013 to 0.256. Higher turbulence increased thermal transport through the laminar bundary layer prevailing in the forward hemisphere, and significantly retarded the point of separation from about 87° to 106° as measured from stagnation. An increase in the Reynolds number shifted the point of separation forward and altered the behavior in the wake. In the separated wake region, the experimental evidence indicated that the vortex reattached to the rear surface and formed a new boundary layer that resulted in a decrease in the local thermal transfer.