Very recently, an optical instrument for measuring sizes and concentrations of spherical particles in a pipeline has been developed by the principal investigators. Based on this experience, we propose to investigate the feasibility of developing a reliable optical particle instrument which will meet the following requirements: (1) it can measure spatial and temporal distributions of particle velocity, size, and mass flux in a gas-solid suspension flow; (2) accurate measurements can be made for small particles with a concentration of up to 500 particles/cm(3) or approximately 500 gram/m(3) for snow powder; (3) the detection cross-sectional area and volume can be adjusted to optimize any measurement requirements; (4) the location of the sensing volume can be easily changed so that local properties of flow characteristics at various points can be measured. Thus the instrument can be used for measurements in wind tunnels; (5) it can be used for field measurements under cold and windy weather conditions. The phase i work will provide a good foundation for further integration of the system into a highly reliable and accurate particle instrument with special applications to army needs.
