Isotherms of Natural and Forced Convection Around a Heated Horizontal Cylinder Embedded in a Porous Medium - Selected Topics of Computational and Experimental Fluid Mechanics - page 227

5.1 Isotherms for a Horizontal Line Source of Heat Under
a Uniform Stream
The second part of the experiment consists of obtaining the isotherms by inducing
a continuous stream of air at different configurations. It is important to say that the
constant stream of air was injected at three different pressures (49kPa, 73.5kPa,
98kPa) and the increase of the injection pressure is seen to delay the time for which
the buoyant plumes reach the steady state. The final form of the buoyant plume was
not modified as time elapses. In Fig. 5 the final shape of the plume, as a result of the
induced free stream of air in the upper part of the porous medium can be seen. It
is clear that under this new condition the convection dominates over the conduction
even in the zones close to the source of heat. The plumes for this cases take elliptic
shapes which are more strongly change toward the direction of the induced stream.
In a further experiment, the air stream was injected at the lower part of the
porous medium. The resulting plume can be seen in Fig. 6 . It is evident that the final
Fig. 7 Infrared images of the isotherms around the heated cylinder due to forced convection induced
from different air injection angles (measured with respect to the vertical axis): a 30 ⓦ , b 45 ⓦ , c 60 ⓦ ,
d 70 ⓦ