Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/4/2006
Publication Date: 4/4/2006
Citation: Smith, C.K., Wren, D.G., Chambers, J.P. 2006. Estimation of particle sizes for a range of narrow size distributions of natural and suspended in water using multifrequency acoustic backscatter. In: Proceedings of the 8th Federal Interagency Sedimentation Conference, April 2-6, 2006, Reno, Nevada. CDROM. Interpretive Summary: A key weakness in acoustic measurement of suspended sediment is the dependence of backscatter strength on the size of the particles in suspension. In the current work, an algorithm for combining data from three acoustic frequencies, generated from one acoustic transducer, is developed for particle sizes from approximately 0.1-1 mm in diameter.
Technical Abstract: The measurement of particle size using multiple, megahertz range acoustic frequencies has been focused on particles with radii of 50'm -150'm. The present study seeks to extend the applicability of the technique to particles with radii ranging from 50'm -425'm. A single acoustic transducer, transmitting a waveform with three peak frequencies, was used to measure backscatter from natural sand particles entrained in a turbulent jet. An approach similar to that taken by Sheng (1991) was used in the data processing, where particle size estimates were created by comparing theoretical ratios of the backscatter form factor and size density to measured ratios. It was found that the method produces 0.1%-36% error for particles with radii of 150'm - 425'm and 24%-160% error for particles with radii of 75'm - 150'm, depending on the concentration of the suspended particles. This work has been supported by the USDA.