Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Air Flow Seperation Question... (where to mount roof VG's on Nissan Cube)

donee · 07-04-2010, 06:25 PM

Hi Chaz,

Boy are you wound up about this.

First off, I am not trying to sell these things. The OP has already spent his money, and anybody else watching should see if the OP applies my advice, and it results in any improvements before buying these things.

My words were "effective cross-area", which I meant to say "effective cross section area". Your reply comment to this is a thought-limiting semantic. As a degreed engineer , with patents, I let myself out of the box when brainstorming. Its a good thing.

You speak the aerodynmacist lingo well. I am not an aerodynamacist, and explain what I am trying to say in my simple intuitive understanding.

I have run tests with yarn tufts on the side of my Prius and turbulator strips in this area of the windshield. There is a very significant effect in windless conditions, and .06 inch thick Turbulator is an even smaller disturbance to the flow than a VG would be, and they do have a real effect. So, its not improbable that a VG on a car with a much more vertical windshield to also have an effect.

On the Cube windshield, the VG will be an almost horizontal thin blade. And my advice was to find the local flow direction, and orient the blade to be nearly parallel to that local flow direction. I found on my Prius, to my great supprise, that the flow was about 30 degrees off the axis of the car in the upper corners of the windshield! I am currious if the air will be much greater than the 30 degrees on the Prius (my guess) or less. My expectation is the air will be flowing almost sidways on the Cube, due to the nearly vertical windshield. Which represents a much greater flow momentum to disturbe the side-slip air.

One way to look at this, is there is a psuedo-pipe of high pressure air in front of the car, where the pipe is made of stretchy plastic. How easily the air flows down the side of the car, will effect how wide the stretchy pipe stretches. The wider the pipe, the more power it takes to hold it at pressure.

Again, we are commenting to the OP to try this, with no garuntees it will work. Just try it and see what happens.

07-04-2010, 06:25 PM	#28 (permalink)
donee EcoModding Apprentice Join Date: Jan 2008 Location: Chicagoland Posts: 204 - - '10 Toyota Prius III w/Navi Thanks: 4 Thanked 12 Times in 12 Posts	Hi Chaz, Boy are you wound up about this. First off, I am not trying to sell these things. The OP has already spent his money, and anybody else watching should see if the OP applies my advice, and it results in any improvements before buying these things. My words were "effective cross-area", which I meant to say "effective cross section area". Your reply comment to this is a thought-limiting semantic. As a degreed engineer , with patents, I let myself out of the box when brainstorming. Its a good thing. You speak the aerodynmacist lingo well. I am not an aerodynamacist, and explain what I am trying to say in my simple intuitive understanding. I have run tests with yarn tufts on the side of my Prius and turbulator strips in this area of the windshield. There is a very significant effect in windless conditions, and .06 inch thick Turbulator is an even smaller disturbance to the flow than a VG would be, and they do have a real effect. So, its not improbable that a VG on a car with a much more vertical windshield to also have an effect. On the Cube windshield, the VG will be an almost horizontal thin blade. And my advice was to find the local flow direction, and orient the blade to be nearly parallel to that local flow direction. I found on my Prius, to my great supprise, that the flow was about 30 degrees off the axis of the car in the upper corners of the windshield! I am currious if the air will be much greater than the 30 degrees on the Prius (my guess) or less. My expectation is the air will be flowing almost sidways on the Cube, due to the nearly vertical windshield. Which represents a much greater flow momentum to disturbe the side-slip air. One way to look at this, is there is a psuedo-pipe of high pressure air in front of the car, where the pipe is made of stretchy plastic. How easily the air flows down the side of the car, will effect how wide the stretchy pipe stretches. The wider the pipe, the more power it takes to hold it at pressure. Again, we are commenting to the OP to try this, with no garuntees it will work. Just try it and see what happens. Last edited by donee; 07-04-2010 at 06:34 PM..