Amplification of heat transfer by local injection of fluid into a turbulent tube flow

It is demonstrated experimentally that local fluid injection into a turbulent tube flow gives rise to substantial increases in the heat transfer coefficients in the region downstream of the injection station. In the experiments, fluid was injected into a mainstream flow through a ring of discrete holes situated just upstream of an electrically heated test section. Water was the working fluid. The augmentation of the heat transfer coefficients due to injection is found to increase as the ratio of the injected flow to the test section flow increases. The extent of the augmentation is greater for low Reynolds number turbulent flows than for high Reynolds number turbulent flows.