Airflow measurement - again...

[Kalle Pihlajasaari]

Hi Andrew,

> What I'd be interested in is a LDA (laser-doppler-anemometery) type 
> air velocity sensor.  If we can make cheap CD players, we should be 
> able to make cheap LDA units.

Tempting but it would get dirty and then you would have to get out
at the traffic lights with an ear-bud to clean the lens :-)

However, accoustic stuff might be interesting, get doples and
densiti measurements with just one sensor.  Have two reflection targets
one across the diameter of the manifold and measure return time
to calculate speed of sound in the medium, may give you full
pressure and temp compensated density but could give you density
given temperature anyway.  And another 'beam' pointing up or
downstream with doppler measurement.  Would have to be quite
sensitive but might work.

Or perhaps a receiver up/down stream and measure phase change
in the received signal.  I just figured that you would cancel
any doppler effect from the media flow if you had a return signal.

You could certainly use a electronic tape measure to measure the position
of a small flap or ball in the flow path without much trouble
beyond positioning of the transducer.

Cheers     *<<<-|
-- 
Kalle Pihlajasaari   kalle at ip.co.za   http://www.ip.co.za/ip
Interface Products   P O Box 15775, DOORNFONTEIN, 2028, South Africa
+ 27 (11) 402-7750   Fax: 402-7751    http://www.ip.co.za/people/kalle