- Author
-
Laurendeau, N. F.
|
Goldsmith, J. E. M.
- Title
- Comparison of Laser-Induced Fluorescence Methods for Measurement of Hydroxyl Concentration in Flames.
- Coporate
- Purdue Univ., West Lafayette, IN
Sandia National Labs., Livermore, CA
- Book or Conf
- Combustion Institute/Canadian and Western States Section. Spring Meeting, 1986. April 27-30, 1986.,
Banff, Alberta, Canada,
1-23 p.,
1986
- Keywords
-
flame research
|
flame equations
- Abstract
- We have examined the advantages and disadvantages of four laser-based fluorescence methods by comparing the OH concentration profiles determined by each method in a lean H2/O2/Ar flame at 72 Torr. Relative OH concentrations are determined by monitoring the resulting fluorescence using: (1) single-photon excitation followed by broadband detection of the (0,0) rovibronic manifold; (2) single-photon excitation followed by detection of the (0,1) maniford; (3) two-photon excitation followed by detection of the (0,0) manifold; and (4) saturated single-photon excitation followed by narrowband detection of one rovibronic transition. In each case, good agreement is obtained between the relative fluorescence profiles and the absolute OH concentration profile determined by integration of the one-dimensional flame equations. We also discuss a fifth technique, namely (5) single-photon excitation of the (1,0) band followed by broadband detection of the (1,1) rovibronic manifold. Broadband detection within the (0,1) or (1,1) manifold provides the best compromise between high fluorescence signal and low background, thus giving the most favorable detection limit. However, beause laser-saturated fluorescence is relatvely insensitive to electronic quenching, it offers the best detection limit above 1 atm, and is the fluorescence technique best suited for turbulent flames under practical combustion conditions.