Producing droplets smaller than the nozzle diameter by using a pneumatic drop-on-demand droplet generator

The outcomes of successive droplets impacting onto solid surface of the steam separator in a nuclear power system’s steam generator has a strong effect on the separating efficiency. Due to amounts of influencing factors, experimental research is an important method to study the phenomena of droplet-wall collision. However, because it is hard to generator continuous droplets with controllable uniform size and frequency, experimental studies about successive droplets impacting on solid surface are relative limited. In this study, a novel drop-on-demand (DOD) droplet generator is designed and fabricated based on piezoelectric ceramics, in which successive droplets with a uniform diameter can be generated. Firstly, the structure design of the DOD droplet generator, the setup of the control system and working principle are described in detail in this paper. Then the droplet generating performance of the device under different signal frequency fs, signal amplitude U, duty ratio Dr, and nozzle diameter Dn are investigated experimentally using a high-speed camera at 4000 fps. Finally, the influence of the signal frequency fs, voltage U, duty ratio Dr and nozzle diameter Dn on the diameter of droplet Dd is discussed. A test of successive droplets generated by the device impacting on an aluminum plate is conducted.

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A High Temperature Drop-On-Demand Droplet Generator for Metallic Melts

Micromachines ◽

10.3390/mi10070477 ◽

2019 ◽

Vol 10 (7) ◽

pp. 477 ◽

Cited By ~ 6

Author(s):

Saeedeh Imani Moqadam ◽

Lutz Mädler ◽

Nils Ellendt

Keyword(s):

High Speed ◽

Temperature Drop ◽

Pressure Oscillation ◽

Ex Situ ◽

Droplet Generator ◽

On Demand ◽

Micro Particles ◽

Drop On Demand ◽

Aisi 52100 Steel ◽

Size And Morphology

In this study we present the design and functionality of a pneumatic drop-on-demand droplet generator that produces metallic micro particles with a size range of 300 µm to 1350 µm at high temperatures of up to 1600 °C. Molten metal droplets were generated from an EN 1.3505 (AISI 52100) steel which solidified during a falling distance of 6.5 m. We analyzed the resulting particle size and morphology using static image analysis. Furthermore, the droplet formation mode was analyzed using high-speed recordings and the pressure oscillation was measured in the crucible. The system is meant to be reproducible in all aspects and therefore the in-situ measurements are set to control the droplet size and trajectory during the run. Additionally, the ex-situ measurements are done on the particles in order to characterize them in size and morphology aspects.

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Development of a drop-on-demand droplet generator for one-drop-fill technology

Sensors and Actuators A Physical ◽

10.1016/j.sna.2008.03.006 ◽

2008 ◽

Vol 147 (2) ◽

pp. 649-655 ◽

Cited By ~ 54

Author(s):

Kuang-Chao Fan ◽

Jhih-Yuan Chen ◽

Ching-Hua Wang ◽

Wen-Chueh Pan

Keyword(s):

Droplet Generator ◽

On Demand ◽

Drop On Demand

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Development of a Piezoelectric-Actuated Drop-on-Demand Droplet Generator Using Adaptive Wavelet Neural Network Control Scheme

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.625.615 ◽

2014 ◽

Vol 625 ◽

pp. 615-620

Author(s):

Jin Wei Liang ◽

Hung Yi Chen

Keyword(s):

Neural Network ◽

Adaptive Learning ◽

Tracking Error ◽

Open Loop ◽

Wavelet Neural Network ◽

Network Control ◽

Droplet Generator ◽

Adaptive Wavelet ◽

On Demand ◽

Drop On Demand

This paper presents the design, fabrication and control of a piezoelectric-type droplet generator which is applicable for on-line dispensing. The piezoelectric-actuated dispensing system consists of a linear piezoelectric motor (LPM) actuated table, a plastic syringe, a nozzle, a linear encoder and a PC-based control unit. Adaptive wavelet neural network (AWNN) control is applied to overcome nonlinear hysteresis inherited in the LPM. The adaptive learning rates are derived based on the Lyapunov stability theorem so that convergence of the tracking error can be assured. Unlike open-loop dispensing system, the system proposed can potentially generate droplets with high accuracy. Experimental verifications including regulating and tracking control are performed firstly to assure the reliability of the proposed control schemes. Real dispensing is then conducted to validate the feasibility of the piezoelectric-actuated drop-on-demand droplet generator. The results demonstrate that the proposed scheme works well in developing the piezoelectric-actuated drop-on-demand dispensing system.

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