Lamellar self-blocking grille

[cfg83]

Frank -

Originally Posted by Frank Lee

It's not rocket science!

Yeah, I know, but he designed cropdusters in the 1950's. He knows aero too.

CarloSW2

[Frank Lee]

Just teasing. I want to hear what he says about it!

[cmroseberry]

Yeah, to make it rocket science, you have to add two cups of thermodynamics and a dash of orbital mechanics. I should know.

[Junimrox]

i believe the only way it would work was if the engine didn't have enough air exits, making positive pressure on the inside thus forcing the air to go upwards(because it can't go inside).

EDIT: BTW, this has almost nothing to do with the shape of the grill, but the shape might help to get the air upwards instead of downwards.

[donee]

Hi All,

Ya Know, you could put those wings on a spring loaded pivot. Then the faster you go, the more they tilt up. That would accomplish the same thing. Also, if you let then hang down, they keep the heat in when parked or stopped. In a Prius that is good, but might not be for an idling car. The fan would have to be able to pull them back open.

I somewhat confused on how these work. Wings stall at low-speeds. So, at a low speed the seperation point would be way forward and might act to slow flow. But at real slow speeds, the air easily bends around the wing. So, its like mayber there is a speed of minimal flow? But does a multi-winged lifting body have the same characteristics as a wing by itself? These wings might be so close they intefere with each other's aerodynamics. So does that change how they work?

With the pivot, the wings would begin to close, but then they might not close all the way, because the amount of force is dependant on the mass of the air flowing over the lifting surface. As the gap between the wings closes off, the mass of air through decreases, and so does the force. This might be designed to result in a constant mass flow, no matter what the speed. Is that what is needed by a car? Or is there some other function of cooling fluid flow versus speed?

Maybe one does not even need springs. Just weights along the trailing edge. Again, this might be a Hybrid car solution, as the weights holding the grill shut might be a problem for an car idling in traffic after a long run down the highway.

[Frank Lee]

I think the whole point of the thing is to regulate air flow without moving parts and control mechanisms.

[Junimrox]

the grill being discussed on this topic has no moving parts, no springs, no pivot. Moving ones are easy to understand.

[donee]

Hi Frank and Junimrox,

Yea, I know. I and thinking why not add them. Might make it to easier to make work without a super computer for the CFD.

Ford can afford the the super computer time to save the $2 per grill in cheap bearings over 300,000 cars ($600,000 saved). But can we afford the $60K program to do that analysis, when $2.00 might be cheaper for us.

I am not proposing controls. Just pivots and maybe some biasing weights.

[Junimrox]

yeah, alright, for us its cheaper and easier to do, but that is not what this topic is about.

[cmroseberry]

I would expect that Capri grille to exhibit ordinary behavior rather than strange behavior, especially since the airfoil sections would tend to have low flow resistance. My guess is that someone misinterpreted what they saw the smoke doing during a series of wind tunnel tests on this Capri. Probably the first application of the streamtube concept to better explain automotive cooling airflows began with Shaub and Charles in 1980. The PopSci article predates this insight into the flow physics by four years. The narrowness of the cooling air streamtube at high speeds could easily have made it look like the Capri grille was doing some self-blocking. The greater the external velocity (relative to the internal flow velocity) the smaller that special spot upstream of the vehicle will be that will actually carry the smoke into the inlet. I took a look at some of my old wind tunnel test footage where I used smoke. The smoke wand would leave about a 3/8-in diameter stream behind it. With a 60-mph wind, even though the frontal inlet of the model was about 3 inches wide and 1 inch tall, most of the time I could not get the inlet to swallow all of the smoke from this relatively small stream. In addition, I could just barely see the smoke stream spreading just a fraction of an inch from the inlet opening plane. My hollow models were connected to the suction side of a high-pressure blower; I could manipulate the internal pressure and velocity over a huge range. It could be that for the Capri, the smoke did not spread until after the plane of the grille. I did not have any trouble interpreting my wind tunnel tests because I was already clued-in on the streamtube concept and my models had no grille at all at the frontal openings. If the guys running the test on the Capri did not have the engine fan going, then the cooling flow streamtube would be really narrow.
Back in ’76, the interaction between the external flow and the internal flow was not understood – things are way different now.