Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.
A new method of obtaining flow resistance coefficient for
perforated plates in low Reynolds number flows, such as
natural air convection, was proposed. And some experimental
values are obtained from the viewpoint of thermal design of
electronic equipment casings where some perforations often
used in the outlet and inlet vent to prevent dust from entering
the casing.
The proposed method is based on the two expressions
written for the enthalpy balance and for the balance between
aerodynamic resistance and buoyancy force in a ventilation
model. By these two expressions, flow resistance coefficient
values can be evaluated even when only dissipated power and
temperature rise is known. As a result, the relationship of the
flow resistance coefficient values for perforated plates,
Reynolds number and porosity coefficient is presented in a
form fitting for practical engineering use. 18 kinds of
perforated plates have been used in this study and the range of
Reynolds number defined by the hole diameter and the air
velocity in the ventilation duct was from 0.4 to 95. The
experimental results include the Reynolds number and porosity
coefficient influence on the resistance coefficient for perforated
plates, as well as the perforated plates thickness to the diameter
of hole effect on the flow resistance coefficient.
