Combined forced and natural convection with low-speed air flow over horizontal cylinders

This article describes experimental work on the mixed convection régime with flow normal to electrically heated cylinders. The forcing velocities used were in the range 0·0085–3 ft./sec (i.e. 10 −2 < Re f < 45) and temperature differences in the range 30°C to 200°C (i.e. 10 −3 < Ra < 10) were covered. Correlations are proposed for the forced convection and natural convection conditions. A correlation is also developed for the combined forced and natural convection region by a vectorial addition of the flow parameters, which gives good agreement with the experiments except over a limited range in the contraflow régime.