Formation and Elimination of Satellite Droplets during Monodisperse Droplet Generation by Using Piezoelectric Method

Abstract

One of the key questions in the generation of monodisperse droplets is how to eliminate satellite droplets. This paper investigates the formation and elimination of satellite droplets during the generation of monodisperse deionized water droplets based on a piezoelectric method. We estimated the effects of two crucial parameters—the pulse frequency for driving the piezoelectric transducer (PZT) tube and the volume flow rate of the pumping liquid—on the generation of monodisperse droplets of the expected size. It was found that by adjusting the pulse frequency to harmonize with the volume flow rate, the satellite droplets can be eliminated through their coalescence with the subsequent mother droplets. An increase in the tuning pulse frequency led to a decrease in the size of the monodisperse droplets generated. Among three optimum conditions (OCs) (OC1: 20 mL/h, 20 kHz; OC2: 30 mL/h, 30 kHz; and OC3: 40 mL/h, 40 kHz), the sizes of the generated monodisperse deionized water droplets followed a bimodal distribution in OC1 and OC2, whereas they followed a Gaussian distribution in OC3. The average diameters were 87.8 μm (OC1), 85.9 μm (OC2), and 84.8 μm (OC3), which were 8.46%, 6.14%, and 4.69% greater than the theoretical one (81.0 μm), respectively. This monodisperse droplet generation technology is a promising step in the production of monodisperse aerosols for engineering applications.

Additive manufacturing of micropatterned functional surfaces: a review

“…A bipolar or unipolar signal is given as an input depending on the ink properties [86][87][88][89][90]. Experimental determination of optimal parameters is common, with rheology-dependent thresholds influencing droplet merging [91][92][93][94]. Bipolar waveforms are preferred for damping out vibrations, while unipolar waveforms offer stability with fewer satellites [95][96][97][98][99].…”

Inkjet printing quality improvement research progress: A review

“…Zejian Hu et al noted that, with an ink flow rate of 30 , increasing the pulse frequency from 10 to 30 caused previously split satellite droplets to merge with the main droplet. When the frequency reached 30 , the droplets appeared as uniformly sized single droplets [ 55 ]. When the pulse frequency is 40 , the ink droplets have irregular sizes.…”

Editorial for the Special Issue on Heat and Mass Transfer in Micro/Nanosystems

“…Thirteen articles have been published after peer-review evaluations, and these articles cover a wide spectrum of active research in the frontiers of micro/nanosystems. For example, Hu et al [ 1 ] studied the satellite droplet generation in piezoelectric methods, and found that there are two key parameters responsible for this phenomenon: the pulse frequency for driving the piezoelectric transducer tube and the fluid flow rate. Optimal operation conditions have also been proposed to eliminate the satellite droplets for deionized water.…”