ICE
Gaseous
So as you are in stating we have a negative pressure bubble myth.
Bernoulli like reasoning goes as follows (in fact vacuum cleaner effect) :
As the rotor gets closer to the ceiling the intake streampipe gets blocked, instead of being of multiple of the rotor area it becomes just part of a cylinder. Around the border of that cylinder the air accelarates more creating high speeds and a static pressure drop. In the cylinder volume above the rotor the air will diffuse over the MR which will slow it down again as it bends and flows "vertically" through the MR-disk, providing for the higher rotor efficiency, but I think again with an increase of static pressure.
If reasonable uniformity of inflow persists, which can be questionable if the rotor gets really close, vacuum above the rotor could increase from -1/4 T/A to -T/A.
Due the low pressure differentials I think compressibility of the air still will play only a minor effect (in that sense it is not a real vacuum cleaner).
As far as strength of the effect, I guess you get the rotor closer to the cieling in ICE than in to the ground in IGE...
d3
changed : corrected for major errors and not fully comfortable...
Last edited by delta3; 11th December 2007 at 08:15.