Rapid Concentration Measurements by Picosecond Time-Resolved Laser-Induced Fluorescence.
Abstract
Measurements of probability density functions (PDFs) and power spectral densities (PSDs) are needed to characterize minor species concentrations in turbulent flames. Current techniques can be used to measure PFDs, but they have limited ability to measure PSDs because they cannot monitor a time-series of the number density fluctuations. This report described the development of a new strategy, picosecond time-resolved laser-induced fluorescence (PITLIF), which can possibly be used to obtain measurements of minor species concentrations in flames on the time scale of turbulence. PITLIF was demonstrated by seeding sodium into a laminar H2/O2/Ar nonpremixed flame and monitoring both the integrated fluorescence signal and fluorescence signal and fluorescence lifetime. PITLIF was also used to determine hydroxyl concentrations in laminar CH4/02/N2 flames. The quenching environment was monitored with real-time sampling, and thus the necessary quenching rate coefficient was obtained on the time scale of turbulence. Fluorescence lifetimes of OH were also measured at different equivalence ratios by using the equivalent-time sampling technique. These results compared favorably with predicted lifetimes based on relevant quenching cross-sections and calculated species concentrations.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 12, 1995
- Accession Number
- ADA298290
Entities
People
- Galen B. King
- Normand M. Laurendeau
Organizations
- Purdue University