Re: The truth about "ram air"
Originally Posted by Franc Rauscher
If you put a 3.0" elbow pipe out the window and pipe in about 2 feet of 3.0" PVC tubing you get air to flow thru the pipe. Agreed?
If you cap off the end with a smaller hole in the cap, you will get air to flow thru the hole. Right?
The only reason air would pass thru that hole is because it has a higher pressure than the air in the cabin. The assumpton can be made that the air in the tubing is under pressure. Otherwise the air in the tubing has no reason to pass thru the hole.
It can also be assumed the continuios the ram effect will maintain that increased pressure. roadster with a stick
I recall that the air pressure in the small hole is less than than the air pressure on the incoming side although the velocity is higher. This is the venturi effect and is used in many things, carburetors, spray guns, etc. The air is coming through the hole to maintain equilibrium, nature likes things balanced. The temperature of the air will also change slightly, but return to normal when it regains its pressure. Properly done, significant temperature drops can be obtained.
We know that bends, obstructions, surface finish and diameters in pipes affects flow and pressure, the same principle applies in air and in water.
The ram jet example only goes to verify the statement in the original article that the ram effect only applies at supersonic speeds.
Last edited by onehundred80; Mar 10, 2010 at 12:07 AM.