Observation of electrohydrodynamically atomized dielectric liquids by real-time and high speed infra-red thermal images

Electrohydrodynamic (EHD) atomization or EHD spraying has been used in many industrial applications and more recently for spraying heated dielectric fluids. In this work, an experimental investigation has been conducted using high speed infrared thermal imaging techniques to measure transient temperature distributions of droplets and liquid columns in EHD spraying. The system used is capable of measuring 100 μm particles with transient of 0.1 ms. The experiment was initially conducted in a small drop tower using single heated black ink droplet particles of known size to establish limitations of measuring technique. The technique was then applied to EHD atomization of mineral oil and decane. The results show that the present technique is capable of measuring the dynamics of liquid droplets with a spatial resolution of 200 μm and temperature profiles with 0.1 K accuracy. The effect of applied voltage and liquid flow rates on the maximum surface droplet temperature are discussed in details.