On July 26, 2007 C.C. Lynch & Associates Inc., participated in a flow validation study in conjunction with the USACE Engineering Research Development Center (ERDC) for the purposes of determining the pumping capacity of the New Orleans Levee London Avenue Pumping Station pictured below.
We worked with the contractor to install our sensor just upstream of the USACE ERDC Pitot tube installation. As shown below with Dr. Stephen Maynord of the USACE ERDC from Vicksburg, MS. Dr. Maynord installed a rack of Pitot tubes (pressure orifices) in the channel so that they could calculate velocity at multipoint’s in the cross-section of the 110 inch line with the Pitot tube method.
The technology we used for this project was the Acoustic Doppler Flow Meter (ADFM) from Teledyne Isco. As shown in the following video this unit takes thousands of measurements for velocity in both the upstream and downstream quadrants of the pipe and can perform accurately in applications without laminar flow as may be the case with pumped flow and/or applications with inadequate approach pipe diameters.
The data from this flow study showed a non uniform flow profile which is often problematic for most flow sensors. In this case we witnessed no degradation in the accuracy or performance of the ADFM. In the following picture we can see the velocity is flowing at 8.63 feet per second. Also we can see the non uniform flow pattern of the pipe by the individual beam velocity graph below.
The following picture shows the same site data with the pumps off. Notice how when not being pumped the downstream beam velocities start matching up with the upstream bean velocities as the pipe gravity drains itself.
In the following graph we can see the velocity displayed for X Y and Z Velocity Vectors. You can see the individual velocities with the green Y Velocity which shows the average velocity throughout the cross sections of the pipe. We can also see from the data the velocity is traveling from the right to the left by the red X Velocity.
Here we see the data when the pumps were off and the cross current X flow component is now near zero.
With this information the USACE had two methods of flow measurement with which to validate their pump capacity. The units reported flow data that was within +/- 2% of each other.