Karman Vortex MAF

[Peter Wales]

The Karman Vortex system needs an ultrasonic transmitter and receiver placed
across the air passage. The output from the receiver is mixed with the input
to get a beat signal which is the measure of air velocity.

The air velocity is measured by creating vortices in the air stream and this
is done by putting a triangular obstruction in the middle. Then the air flow
sheds vortices proportionally to the speed of the air going through. It
looks like this in section.

                             |---|
                             |   |Receiver
-----------------------------|___|-----------------------------
                              

->                        /|
                         / | @  @ Vortices :)
->AIRFLOW               /  |
                        \  |
->                       \ |
                          \|@  @


-----------------------------|___|----------------------------
                             |   |
                             |---|Transmitter

It only measures air speed and I have no idea how to calibrate it. The
Mitsubishi system uses bypasses and only measures a percentage of the air
going into the engine. It also has a honeycomb flow straightener in front of
it to remove spurious vortices from the air flow.

I hope this will give you wizards some ideas




Peter Wales                    pjwales at magicnet.net
President Superchips Inc
Chairman Superchips Ltd        "Timing is everything"
Superchips home page with all the answers http://www.superchips.com