Nonlinear Spectroscopy of Multicomponent Droplets and Two- and Three- Dimensional Measurements in Flames
Final rept. 1 Jan 1988-31 Jan 1991,
YALE UNIV NEW HAVEN CT
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Significant progress has been made in the following two research areas 1 Nonlinear spectroscopy of micrometer-size droplets and 2 Development and application of two- and three- dimensional scalar measurement techniques in flames. In the nonlinear spectroscopy area, the following achievements are reported 1 Laser-induced shape deformation of transparent droplets by electrostriction, which pushes against the surface tension force and causes the droplet to bulge 2 Laser-induced shape deformation by heating of absorbing droplets, which were imaged with fluorescence photography 3 Laser- induced breakdown which quenches the stimulated Raman scattering SRS 4 Excitation of SRS with single-mode and multimode Q-switched lasers and 5 Four-wave mixing processes in droplets, such as third-order sum frequency generation. Achievements in multidimensional scalar imaging include the following 1 Measurement of the time evolution in premixed H2-air flames using imaging techniques 2 Development of new techniques for following the time evolution of flow structures in three dimensions 3 Introduction of a technique for visualizing supersonic flows using Rayleigh scattering from condensed-phase droplets 4 Measurement of the complete scalar gradient in a nonreacting flow, which allows calculation of the scalar dissipation 5 Simultaneous CH and CH4 mapping in a turbulent nonpremixed flame, and 6 Investigation of differential diffusion effects.
- Atomic and Molecular Physics and Spectroscopy