HEAT TRANSFER EXPERIMENTS AND A GENERAL CORRELATION FOR IMPACTING WATER SPRAYS ON HIGH TEMPERATURE SURFACES
Experiments were performed to evaluate the heat transfer of monodisperse sprays of large droplet diameters, ranging from 3 to 25 mm, on high temperature surfaces. This range of drop sizes has not previously been studied, and it is of interest to determine their heat transfer characteristics and how they relate to sprays of smaller drops.
Parametric tests showed that the spray heat flux is most dependent on mass flux and droplet diameter, and that there was no discernible relationship between the heat transfer and droplet velocity. These results agree favorably with published results for smaller droplets.
A dimensional analysis showed that the mass velocity of the spray could be substituted for the velocity in the Reynolds and Weber numbers, greatly improving the correlation with the data. The spray Reynolds number, defined as Res = m d/µ, and spray Weber number Wes=m2d/ρσ were shown to correlate data from many authors covering a wide range of spray parameters. This dependency on mass flux and droplet diameter supports the results of the parametric experiments.