New
#61
What is causing the air pressure which causes the air to move is not what is the factor in question. Regardless of what causes the primary airflow, it is the reduction in size of the aperture of the carburetor's throat that causes an additional speed factor to be induced, and this in turn reduces the air pressure within that speed zone.
Since the fan casing does not have a reduction in diameter, it does not effect air speed. What does increase airspeed is the fan blades, which act just like the wings of an aircraft.In our example the casing of the fan with the blades spinning in the smallest part of the aperature is what causes the increase in velocity, and the reduction in pressure on one side of the blades. However it is also what causes the increase in pressure on the other... Just like the curvature of a wing causes an increase in pressure underneath the wing... This is not a closed system... one side can (and does) affect the other.
I may be a tad off on the science --it's been 15 years since I designed cooling systems of any account-- but the palm test explains it very well... It is what the heatsink "feels".