Assessment of Multiple Scattering Errors of Laser Diffraction Instruments
Abstract
The accuracy of two commercial laser diffraction instruments was compared under conditions of multiple scattering designed to simulate the high droplet number densities encountered in liquid propellant rocket combustors. Both instruments employ correction factors to account for multiple scattering at transmission levels down to about 2%. The instrument accuracy was compared in terms of several mean moment diameters as well as the standard deviation of the measured distributions. Results show that the newer instrument with a more recently developed statistical approach to correcting for multiple scattering errors produced significantly greater accuracy than the older instrument that employs a more limited type of analytical correction scheme. The statistical correction scheme resulted in an accuracy of about +1-10% for the volume-weighted volume mean diameter, D43 down to a transmission of about 2%, while the analytical correction approach resulted in an under-estimation of D43 by as much as 45% at a transmission of 2%. With the statistical correction, reasonable accuracy was obtained at a transmission as low as 1% and was limited by the signal-to-noise ratio of the detector.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 17, 2003
- Accession Number
- ADA417435
Entities
People
- Peter A. Strakey
Organizations
- Air Force Research Laboratory