In-situ particle measurement with blurred image processing using telecentric lenses

A system based on trajectory image processing is developed to achieve in situ measurement of particle size, concentration and velocity in dilute gas-liquid two-phase flow, which is hard to be measured by laser particle analyzer. As the single-frame single-exposure image method, velocities of droplets can be easily calculated from the certain exposure time and the moving distance in a trajectory image, avoiding cross-correlation processing. A telecentric lens is used as an important component of the measurement system which can help to get concentration information. This in situ method avoids inversed processes in measurement methods such as light fluctuation method. Particles with defocused blur are also dealt with in the later part of the paper for further investigation of particle size and concentration measurement.