Flow conditioner design for improving open channel flow measurement accuracy from a Sontek Argonaut-SW
Howes, Daniel J., author
Burt, Charles M., author
Sanders, Brett F., author
U.S. Committee on Irrigation and Drainage, publisher
Colorado State University. Libraries
Acoustic Doppler Velocity Meters (ADVMs) have become popular for open channel flow measurement. However, the methods used to calculate mean channel velocity from the ADVM sample (such as flow rate indexing procedure or theoretical computations such as depth-integrated power law) require significant investment in calibration time and channel improvements to provide reasonable calibration accuracy. This study utilized a Computational Fluid Dynamics model validated with the physical Cal Poly flume to design a device to condition the flow through the upward-looking ADVM sampling beams. It was found that a simple linear relationship exists between the mean sample velocity and the actual mean channel velocity when the conditioning device was used. A procedure has been developed to design a flow conditioner for applications in open channels where ADVM devices will be installed. The designed conditioner is shorter than expected and the ADVM requires minimal calibration, reducing the cost of construction and time required for calibration. Test results indicate that the flow rate measurement accuracy from the ADVM with the flow conditioner can be improved to within +/- 2.2% under a range of typical flow rate and depth conditions.
Presented at the fifth international conference on irrigation and drainage, Irrigation and drainage for food, energy and the environment on November 3-6, 2009 in Salt Lake City, Utah.