Augmentation of heat transfer by subsonic diffusion at a nearly separated state

Measurements of mean velocity, turbulence intensity, and wall heat transfer were obtained in a 13 deg total angle of divergence conical diffuser coupled to a constant diameter recovery section. The results indicated that the boundary layer was in a nearly separated state. Turbulence intensity levels approaching 0.4 were observed in the latter stages of diffusion. The convective heat transfer was always equal to or higher than corresponding values for fully developed pipe flow at the same Reynolds number. The augmentation in heat transfer was greatest during the latter stages of diffusion where the Stanton number was nearly three times the pipe flow value.