Session: 5.2.1 - Novel Measurement Techniques in Fluid Engineering I

Paper Number: 158667

158667 - Experimental Analysis of Electrohydrodynamic Atomization of Different Fluids 

Abstract: 

Electrohydrodynamic jets, more commonly known as electrospray, consist of a technique where particles are generated from a liquid under the influence of a high electric field. While only discovered in the early 20th century, electro-spraying has become increasingly important in recent times with applications ranging from the automotive industry, being used in painting and coating, to the aerospace sciences, being utilized in propulsion, and the medical area, seeing its use in drug delivery methods. Given its importance, this study aims to analyse the behaviour of different liquids when atomized by an electrospray. The produced droplets and its characteristics will be analysed with the help of the phase Doppler technique. This technique employs two laser beams, which converge in a single point, and two or more photo detectors, which identify when the beams are diffused by a droplet, providing the velocity, diameter and concentration of the produced droplets.

The different experiments were conducted with three liquids, acetone, ethanol and ethylene glycol, being nebulized with varying parameters such as the emitter diameter, liquid flow rate and emitter to collector distance. The resulting droplets were characterized in terms of size, velocity and droplet concentration. In addition, each trial was performed with a fixed time, as a way to also observe the droplet count that was analysed with the phase Doppler technique, as a means to better compare the efficacy of this technique with varying liquids.

The results obtained display the difference between the three distinct liquids. In the case of ethylene glycol, for example, there was a high difficulty in analysing droplets utilizing the phase Doppler technique, with a rather reduced number of droplets in some cases, and no captured results in others. These droplets, in general, also had significantly higher diameters and lower velocities when compared to ethanol and acetone, due to the properties of the liquid such as its higher viscosity. In the case of ethanol, the results were completely opposite, presenting a higher velocity in the produced droplets but a lower diameter, while also having some instability due to its high volatility. Meanwhile, acetone produced the best results, having a reasonable value for both particle size and diameter, while also presenting results with a more consistent number of analysed droplets, and a better concentration.

This study offers a better understanding of the different parameters involved in the electro spraying process, so that they can be used in a way that optimizes the electro spraying technique in order to achieve desired droplet properties for specific and precise applications. Furthermore, it shows the limitations present in the phase Doppler technique utilized but also its efficacy in obtaining quantitative values for the sprayed droplets in varying parameters.

Presenting Author: Miguel Moreira Universidade da Beira Interior

Presenting Author Biography: