FIBER-OPTIC SPECTROPHOTOMETRY TO MEASURE TURBOJET EXHAUST-SOOT PARTICLE-SIZE DISTRIBUTION FUNCTION

The present work deals with the design, development, testing and implementation of a real-time monitoring system to determine the particle size distribution of soot. The novel technique shall make use of multiwavelength analysis of light scattering properties of the particles to infer the particle index of refraction, the soot number density and the particle size distribution. The Phase I technical objectives are the following: a) Investigate the feasibility of using multiwavelength light scattering and extinction properties of sooting flows from which the size distribution of soot can be inferred; b) Determine the particle dynamic range of the proposed instrument, sensitivity, and limitations as applied to the specific application; c) Investigate the relative merits of using a single laser, i.e., an Argon-ion, as opposed to three different lines with widely spaced wavelengths; d) Develop a breadboard system from which preliminary measurements of soot can be measured from a laboratory scale flame. The effort shall consist of using three different wavelengths of laser light to obtain the light scattering and extinction from soot particles to infer the complex index of refraction of soot, its concentration, and the particle size distribution. The use of solid state diode lasers and photodiodes shall be incorporated in the novel instrument to obtain a compact probe to be used in typical combustion environments.