An analytical and experimental study of turbulent gas flow between two smooth parallel walls with unequal heat fluxes

Abstract

This paper contains the results of a theoretical and experimental study of asymmetric heat transfer to air in fully developed turbulent flow between two smooth parallel plates. The heat fluxes at the plate surfaces were of different magnitude; in the theoretical analysis, each surface heat flux was assumed to be uniform in the flow direction. In the experimental work, two-dimensional flow was simulated by means of long ducts of large aspect ratio. Velocity distribution and friction data in adiabatic flow were recorded, and these showed good agreement with accepted relationships. Heat-transfer measurements were made firstly with one wall insulated and then with heat transfer at both walls. In the latter series of experiments, the wall fluxes were unequal and of opposite sign. The experimental heat-transfer coefficient for the wall through which heat was transferred to the fluid was observed to be less than the accepted value for the case of symmetrical heat transfer and to decrease as the degree of asymmetry increases. A decrease in heat transfer coefficient of up to about 40 per cent was measured. The theory, which is based on the analogy between the transfers of heat and momentum, is more rigorous than that published by the author in a previous paper and is adequately supported by the experimental data. It is concluded that the heat-transfer coefficient is dependent on the heat-flux distribution around the circumference of the flow section.