The effect of local gas velocity and temperature on local heat transfer to a sphere in a high‐temperature jet

Correlations for overall or local heat transfer to spheres based on flow conditions prevailing just ahead of the sphere or in its absence constitute an oversimplification, particularly in the presence of the steep temperature and velocity gradients existing in a plasma flame. This study presents correlations based on local values of heat flux and on local values of the free‐stream temperature and velocity of an argon plasma jet, as well as data obtained in helium. A single correlation for the argon and helium data was obtained with the use of a thermal conductivity ratio correction. The characteristics of the argon plasma jet were interpreted according to classical jet mixing theory.