[Acoustics] Speed profile

[David S Mueller]

The Doppler shift is directional, it can only be measured along an axis 
parallel to the direction of the transducer output. Three transducers are 
required to resolve a 3-D velocity and this assumes that the velocity 
measured by each transducer is the same. Errors are introduced into the 
vector resolution if one or more of the beams measure velocities 
significantly different from the others. Using one beam would only allow 
you to measure the velocity vector parallel to that beam. To resolve that 
into a horizontal velocity would require assumptions about the vertical 
velocity, which in high-velocity turbulent flow may introduce errors into 
your horizontal velocity. A better solution would be to use an ADV, if 
possible. The other option would be to use either a Nortek BoogieDopp or 
RDI Rio Grande and align two opposing beams with the flow. The Rio Grande 
would still require user processing to achieve the desired answer.

David S. Mueller
U.S. Geological Survey
9818 Bluegrass Parkway
Louisville, KY 40299
------------------------------------
Voice: (502) 493-1935
Fax:      (502) 493-1909
Email: dmueller at usgs.gov




Steve Renaud <srenaud at genivar.com>
Sent by: acoustics-bounces at simon.er.usgs.gov
11/21/2003 10:11 AM

 
        To:     acoustics at simon.er.usgs.gov
        cc: 
        Subject:        [Acoustics] Speed profile


Hello Everyone

I would like to measure a speed profile in a very high acceleration zone 
with
our Sontek Mini ADP. Since this instrument makes an speed average from 
three
beams measurement on a very wide area, I wonder how If it is possible to 
use
only one beam? What would be the best setting to get the best values? I
Suppose
I would need to get a good alignment of the ADP unit with the flow. Does
anybody have experience of these kind of measurements?

Good weekend

Steve

Steve Renaud, P.Eng., M.Sc.
Project Manager

GENIVAR Consulting Group inc.
Hydroenergy and Hydraulic Development
5355, boul. des Gradins
Quebec City (Quebec) G2J 1C8
www.genivar.com

Phone.: (418) 623-2254
Fax. : (418) 623-2434

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