Accession Number : ADA298290

Title :   Rapid Concentration Measurements by Picosecond Time-Resolved Laser-Induced Fluorescence.

Descriptive Note : Final rept. 1 Sep 91-31 Mar 95,

Corporate Author : PURDUE UNIV LAFAYETTE IN SCHOOL OF MECHANICAL ENGINEERING

Personal Author(s) : King, Galen B. ; Laurendeau, Normand M.

PDF Url : ADA298290

Report Date : 12 MAY 1995

Pagination or Media Count : 21

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.

Descriptors :   *LASER INDUCED FLUORESCENCE, *CONCENTRATION(COMPOSITION), *FLAMES, DENSITY, MEASUREMENT, RATIOS, INTEGRATED SYSTEMS, ENVIRONMENTS, REAL TIME, RATES, TURBULENCE, SODIUM, POWER SPECTRA, PROBABILITY DENSITY FUNCTIONS, QUENCHING, TIME, VARIATIONS, SCALE, COEFFICIENTS, SIGNALS, SAMPLING.

Subject Categories : Lasers and Masers
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE