Transition of measuring instruments for liquid atomization

There are various types of atomization measurements, mainly for liquids, and it is no exaggeration to say that it is the history of particle size measurement. When measuring the diameter of atomized droplets, it has long been a question of whether the measuring instruments are really showing the correct values. The Phase Doppler Interferometer (PDI), which appeared in this history, can simultaneously measure the particle size and flow velocity of droplets, and can also display the density and flux per unit volume (cc/cm2/s). When the measurement target is a spray, this means that larger particles have faster velocity and smaller particles have the opposite. In this article, I will look back on the history of measuring instruments related to atomization over the past 40 years, from the late 1980s when I first became involved in the world of atomization to the present day, focusing on the Phase Doppler Particle Analyzer.