Transport of momentum and energy in a ducted jet: I. Experimental study of a nonisothermal jet of air discharging into a duct

Abstract

AbstractA heated jet of air from an 0.898‐in. standard A.S.M.E. nozzle was discharged into a 4‐in. steel duct, well insulated over its entire 10‐ft. length. Air from the region surrounding the nozzle was entrained into the duct. At a number of points along the duct, radial profiles of air velocity and temperature were obtained by means of a probe which combined an impact tube and a thermocouple. The temperature at each of several points along the duct wall was indicated by thermocouples imbedded in the wall.In the experiments reported here the velocity at the jet was 585 ft./sec.; the temperature of the jet was about 220°F. and that of the entrained air was about 88°F. The total air flow rate through the duct was 0.67 lb./sec., and the heat flux was 4.9 B.t.u./sec., with the temperature of the entrained air taken as the datum.The radial and axial profiles of velocity and temperature are compared and discussed; the temperatures of the stream near the duct wall and of the duct wall itself are given. Conservation of mass and heat was checked by graphical integration of the radial profiles.