An experimental study of the thermal plume developed above a finite cylindrical heat source to validate the point source model

Abstract

An experimental study of the thermal plume developed above a variable cylindrical source of finite dimensions was conducted with the aim of verifying the corresponding point source model. The heat source was a 1 m diameter, 1 m high cylinder featuring five zones (four 0.25 m high cylindrical surfaces and a top disk) of identical surface area. Two different configurations were tested: in the first, only the top surface of the cylinder was heated and, in the second, both the top disk and the related cylindrical zone were heated. Surface temperatures were chosen to maintain the same source convective power for both situations. A battery of nine anemometric probes recorded simultaneously plume velocity and temperature distributions. These measurements allowed the plume thermal and dynamic radii above the source to be deduced. These radii vary linearly with height and they enable the plume virtual origin to be situated. If the virtual origin of each source is taken as a starting point, we observe that, in both test cases, the plumes develop in the same way, effectively validating the point source model. Velocity measurements also allowed the plume flow rate to be evaluated. The values found agree closely with those calculated using the relation that gives plume flow rate as a function of source convective power and height above the virtual origin.