Sampling Submicrometer Particles Suspended in Near Sonic and Supersonic Free Jets
Abstract
This investigation was concerned with sampling submicrometer particles in perisonic flows. Aerosol particles having a number mean diameter of 0.8 micrometers and a geometric standard deviation of 1.28 were accelerated to Mach 0.6, 0.8, 1.26, or 1.47 through a flow nozzle. Aerosol mass concentrations were determined using a small bore probe in the jet and by a large bore probe sampling isokinetically upstream of the jet nozzle. The results of both samples were compared to compute the sampling error associated with the high speed jet sample. Studies at Mach 0.8 with four sampling probes having inlet wall to bore area ratios ranging from 3.8 to 0.28 (a knife edge) demonstrated that probe wall thickness effects are not significant when the sample is extracted isokinetically. Subisokinetic experiments using the knife edged probe showed relative errors of 124 + or - 12 percent when sampling at 20 percent of the isokinetic condition. The subisokinetic results are compared favorably with the extended empirical results of other authors. For the supersonic cases it is shown that the subsonic velocity downstream of the sampling probe bow shock can be used in estimating the sampling error.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1977
- Accession Number
- ADA047829
Entities
People
- Joseph A. Martone
- Peter S. Daley
- Richard W. Boubel