Rear diffuser
11-20-16, 10:55 AM
#1
Rookie
Thread Starter
Rear diffuser
I saw this on eBay. Thought it looked pretty interesting and didn't look as bad as some things I've seen people come up with. Would it actually work though as a diffuser and would it work on the car?
11-21-16, 02:38 AM
#8
No. That eBay one will be purely for aesthetics. I doubt anyone makes an actual functioning rear diffuser for this platform because R&D costs to do such a thing would be huge. Unless you're tracking your car a rear diffuser is pretty pointless as it will slow you down in a straight line.
11-28-16, 04:28 PM
#10
No. That eBay one will be purely for aesthetics. I doubt anyone makes an actual functioning rear diffuser for this platform because R&D costs to do such a thing would be huge. Unless you're tracking your car a rear diffuser is pretty pointless as it will slow you down in a straight line.
You can make a diffuser with sheet-metal.
The optimal angle is 8 degrees; according to exotic-car manufacturer designs. The space between each fence is more or less negligible; unless you're racing professionally, then you can kinda "eye it"; rather than have exactitude; unless you have a visual-means of experimenting with airflow.
The Venturi-Effect is how diffusers work; the larger opening in the rear produces a greater vacuum; fascilitating incoming flow from the front (Dynamic Pressure); which thereby reduces the pressure-zone beneath the vehicle, creating downforce (Bernoulli's Principle).
It'll work on just about any car, provided you're using an undertray. Our challenge is simply that nobody's made one for SC's.
11-28-16, 05:10 PM
#11
None of that is true.
You can make a diffuser with sheet-metal.
The optimal angle is 8 degrees; according to exotic-car manufacturer designs. The space between each fence is more or less negligible; unless you're racing professionally, then you can kinda "eye it"; rather than have exactitude; unless you have a visual-means of experimenting with airflow.
The Venturi-Effect is how diffusers work; the larger opening in the rear produces a greater vacuum; fascilitating incoming flow from the front (Dynamic Pressure); which thereby reduces the pressure-zone beneath the vehicle, creating downforce (Bernoulli's Principle).
It'll work on just about any car, provided you're using an undertray. Our challenge is simply that nobody's made one for SC's.
You can make a diffuser with sheet-metal.
The optimal angle is 8 degrees; according to exotic-car manufacturer designs. The space between each fence is more or less negligible; unless you're racing professionally, then you can kinda "eye it"; rather than have exactitude; unless you have a visual-means of experimenting with airflow.
The Venturi-Effect is how diffusers work; the larger opening in the rear produces a greater vacuum; fascilitating incoming flow from the front (Dynamic Pressure); which thereby reduces the pressure-zone beneath the vehicle, creating downforce (Bernoulli's Principle).
It'll work on just about any car, provided you're using an undertray. Our challenge is simply that nobody's made one for SC's.
04-16-17, 01:23 PM
#14
Lexus Champion
The purpose of a diffuser is to slow the air velocity so the static pressure increases. Why? Because when the static pressure at the rear of the car increases the pressure drop from the front of the car to the rear is lessened. Less delta pressure across the vehicle means there is less drag. The depicted diffusers are hardly worth considering. The angle of a usable diffuser is very small. Once the airflow separates from the diffuser wall, there will be no more increase in the static pressure. Hence, it just quits working. You must have a smooth flow entering the diffuser for it to do anything. Consequently, the need for a smooth surface on the bottom of the car.
To determine how effective a diffuser might be on a particular car it should be determined by wind tunnel testing. A model would be made and the drag coefficient, CD, could be accurately determined. This is done all the time in aircraft design. One could test a model and then retest with a "diffuser" installed on the rear.
To determine how effective a diffuser might be on a particular car it should be determined by wind tunnel testing. A model would be made and the drag coefficient, CD, could be accurately determined. This is done all the time in aircraft design. One could test a model and then retest with a "diffuser" installed on the rear.
04-17-17, 10:17 PM
#15
The purpose of a diffuser is to slow the air velocity so the static pressure increases. Why? Because when the static pressure at the rear of the car increases the pressure drop from the front of the car to the rear is lessened. Less delta pressure across the vehicle means there is less drag. The depicted diffusers are hardly worth considering. The angle of a usable diffuser is very small. Once the airflow separates from the diffuser wall, there will be no more increase in the static pressure. Hence, it just quits working. You must have a smooth flow entering the diffuser for it to do anything. Consequently, the need for a smooth surface on the bottom of the car.
To determine how effective a diffuser might be on a particular car it should be determined by wind tunnel testing. A model would be made and the drag coefficient, CD, could be accurately determined. This is done all the time in aircraft design. One could test a model and then retest with a "diffuser" installed on the rear.
To determine how effective a diffuser might be on a particular car it should be determined by wind tunnel testing. A model would be made and the drag coefficient, CD, could be accurately determined. This is done all the time in aircraft design. One could test a model and then retest with a "diffuser" installed on the rear.
There is no "static" pressure. It's a moving vehicle; so all pressure is "dynamic".
Secondly, there is a steady stream beneath the vehicle, starting front to back; known as a laminar-flow.
The pressure-reduction occurs directly beneath the vehicle, within that flow; so the area of greater (atmospheric) pressure is outside that area. The exiting airflow out the rear, always produces a vacuum, called a Venturi-effect; which facilitates the flow from the front, in order to increase its velocity; thereby lowering the pressure (Bernoulli's Principle) under the vehicle, creating downforce. In sum, you're turning the car into a wing; pulling itself down to the road more firmly; just like the rear one does on your trunk.
The fences, which are the dividers/fins help keep maintain the flow, by creating a barrier from outside air potentially entering to disrupt it. They keep the stream "neat" in a sense.
All of that might be what you meant; I'm not ******* your post; it just sounded really convoluted the way you wrote it IMHO.