Online calculator for the pressure drop in perforated plates.

The procedure is targeted for typical electronic cooling applications. Hole size ~4 mm and velocity<5 m/s.

Related links
Thermal design for electronics
Thermal online tools
Unit conversion
Comments

General

The procedure is uses the Carnot-Borda loss equation with a contraction factor of 0.7. The calculation is uncertain for porosities>60%. Factor 2 lower values have been observed for ideal conditions. Another uncertainty is the impact of dust deposits. Chapter 14 of the theory document deals with these issues more in depth.

The flow pattern of air that enters a hole looks much as a time glass. The waist is at ~0.6*D. The plate thickness therefore has little impact if it is smaller than the hole diameter. Empirical data also shows that the shape of the hole is of little importance.


Inputs

Porosity
Is the ratio of the free cross section to the total cross section.

Velocity
Is the maximum velocity. The calculation is made in 30 steps up to this velocity.

Head loss
Is the pressure loss coefficient base on the dynamic pressure of the approaching air.


Edit options

Save/Delete last
Saves and deletes the curves in the diagram. Maximum 5 curves can be saved.

Note

Clicking in the diagram opens a panel with tabled results that can be copied and pasted into a spread sheet program.

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