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Old 06-26-2019, 11:52 AM   #45 (permalink)
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Originally Posted by NeilBlanchard View Post
Interesting discussion - I would think the slot just ahead of the moving "roadway" belt would be supplying air to make the relative motion of the roadway and the boundary layer of air be stationary relative to each other.

With the "extra" air flow introduced at the front of the belt - the belt's motion would possible accelerated the already moving air. By the way, what affect would the texture of the belt / roadway have on things?

By vacuuming some air away from in front of the belt would seem to INCREASE the motion of the air relative to the moving belt, and thereby make the effect of the moving belt, and therefore lowering air pressure under the car - which makes it LESS "realistic"; not more.
Your thinking is right on.It's just a matter of 'tuning'.Some full-scale tunnels are capable of on the order of 160-mph flow velocities.I don't think you can run a moving roadway at that kind of speed.If so,then there's a possibility that the airspeed in the test section will overwhelm the 'roadway',and introduce a flow condition you'd never see in the real world.Also,the flow on either side of the roadway would be stationary,compared to the moving floor,which would introduce shearing forces and vorticity if not compensated for.The tunnel technicians need to keep sharp.
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