An Instrument for Spray Droplet Size and Velocity Measurements

Laser light scattering techniques that measure the size of single droplets at a time have experienced difficulties when applied to high number density sprays. This problem has been alleviated by developing the particle sizing interferometric method for the off-axis detection of scattered light. The method has the advantages of being insensitive to the absolute intensity of the light scattered and light absorbed by the droplet and measures the droplet size and velocity simultaneously. A theoretical description of the technique is given along with experimental verifications of the results. The experiments showed that the method can produce accurate in situ measurements of typical nozzle sprays when large off-axis light collection angles are used.