The purpose of this Small Businness Innovation Research (SBIR) Phase I project is to examine the feasibility of extending the interferometric phase Doppler technique to irregular particles. Phase shift signals generated by the irregular particles will be interpreted as the outcome of a stochastic process, i.e. a given particle (depending upon its orientation in the measurement volume) is expected to generate a particular phase shift with a certain probability. This project aims at experimentally examining the nature of the phase shift probability functions, associated with different kind of irregular and inhomogeneous particles (preliminary measurements indicate that these functions may be fairly simple in form). For this purpose, irregular particles will be qualified using alternative techniques that measure particle volume, cross-sectional area or aerodynamic diameter. The theory of geometrical scattering by statistically random particles will also be developed to predict the above probability functions. Finally, numerical inversion schemes will be developed to deduce velocity-resolved particle size distributions from the measured phase shift distributions. The successful completion of Phase II, if approved, will lead to a very desirable technique for non-intrusive and spatially-resolved measurement of irregular particles in multiphase flows. Measurements would be conducted through a single optical window and would be independent of laser intensity. Currently, there is no equivalent commercial or non-commercial instrument available.
