Droplet velocity and energy characteristics of continuously variable spray based on pulse width modulation

A kind of continuously variable sprayer based on pulse width modulation was developed. The spray characteristics of the sprayer were studied with three kinds of nozzles such as flat fan-shaped nozzle, hollow cone nozzle and solid cone nozzle. A phase-Doppler particle dynamic analyzer (PDA) manufactured by Dantec Company was used to measure the spray droplet size and velocity below the nozzle of 50 cm. The measurement results were statistically analyzed. The variation rules of droplet velocity, spray specific energy, kinetic energy median diameter and volume median diameter with spray flow were obtained. The droplet velocity and the spray specific energy both decreased with the decreasing of spray flow rate, and especially when the duty cycle was less than 75%, the decrease of the spray droplet velocity was significant. Kinetic energy median diameter decreased with the decreasing of spray flow rate, which was the same as the variation of volume median diameter, and the results also indicated kinetic energy median diameter was related to the spray droplet size.