Quote:
Originally Posted by Harpo
With Upper Grill Block, I've noticed that below 50-55mph the drops that form below the wiper at rest migrate with the flow over the hood fairly uniformly. However, after 55mph it appears that some turbulence (at least non-laminar flow) sets in forward of the wiper, actually causing the dops to stagnate, and sometimes retreat to toward the front. I can't determine whether it's a function of the wiper blade interference drag at that speed, or just that the airflow changes off the hood making a low pressure area just forward of the lower windshield.
It would be intersting to witness it without the Upper Grill Block to see if it's altered.
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I believe carmakers design in a region of stagnated air adjacent to the windshield to tap for cabin ventilation.On the T-100 the rainwater stops about a foot (300-mm) in front of the windshield base.Perhaps you've seen NASCAR racers drafting.If you look,you'll notice that the combustion air inlet is positioned at the windshield base to take advantage of this pressure peak.Since they're drafting,there's no ram-air available at the grille and they'd lose a tiny bit of HP if they tried to harvest that area.I suspect that your windshield wipers are "harbored" within this stagnant pool of air.Wind-tunnel smoke-flow images usually show the air deflecting over this whole area,as the flow is diverted by the bubble.