Quote:
Originally Posted by d0sitmatr
I work with the stuff and I can say with absolute truth that with the thickest screen material you can find you will block about 34% airflow.
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I think using screening as an air block material that is invisible to airflow at low speed and opaque to air flow at high speed is brilliant.
It is common knowledge in ventilation system design that the higher the volume of air trying to pass through a restriction the higher the resistance. It isn't possible to say that a screen would only block 34% of air, period. It depends on the flow rate of the air trying to get through. It is likely true that a screen in a window in a light breeze would block about 1/3 of the air flow, but the same screen in the same window in a hurricane would block a much higher percentage. Used as a grill block, I think most of the air would be blocked at 60 mph. However, if the screen does pass too much air a simple way to solve that problem would be to use two layers of screening, which would halve the open area. You could even use several layers applied in different areas to fine tune your grill block to let more or less air through at various places.
I can also envision the airflow deflected around the screen being more laminar and less turbulent than a solid grill block because the air flow would be changed less abruptly than with a solid piece. This would be more pronounced with a vertical grill rather than with a sloped grill.