Heat transfer to spheres in a confined plasma jet

An experimental study was conducted with a 40 kw. direct‐current nitrogen plasma jet confined in an 8.00‐in. i.d. graphite chamber. The heat transfer rates were determined at a test section located 10.5‐in. below the entry of the jet to water‐cooled 0.625 and 1.000‐in. diameter spheres at temperature differences of up to 5,000°f. and over the Reynolds number ranges of 600 to 4,300. The data were correlated in terms of the Nusselt and Reynolds numbers, with gas properties taken at the bulk temperature. The high intensity of turbulence increased the heat transfer rates to above most of those previously reported, and Reynolds number exponents typical of turbulent systems were obtained.