Size, velocity and flow concentration measurements in sprays by laser-Doppler-anemometry

A modified laser Doppler anemometer which uses the Doppler phase shift from two photodetectors for particle size correlations and measures the size and velocity of discrete small particles simultaneously is described. The new method delivers two-dimensional distributions for enclosed flow situations in multiphase flow systems with a very high spatial resolution and with accepted rates of counted events of about 250 per second. The local behavior of drops in the free flow situation of a spray generated by a water nozzle, and the role of the air entrainment are discussed. The presented experimental results verify the use of the Doppler-phase-shift method in complex multiphase flow systems like liquid atomization and spray systems.