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Abstract
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Experimental investigation of Electrohydrodynamic developing falling film flow of transformer oil has been
conducted within an inclined rectangular channel and hydrodynamic characteristics of the flow have been
revealed. The electric field has been generated by five overhead thin wire electrodes connected to the positive
high DC voltage on the air and the grounded plate electrodes which are placed upon the floor of the channel.
It is the first time that the wavy behavior on a liquid falling film's interface has been created by this electrode
configuration. A non-intrusive method has been used to measure the local flow structure by a high-speed
camera, then statistical characteristics of the wavy falling film have been computed by image processing of
the captured video frames. By applying 13-16 kV to the wire electrodes, the influence of EHD force on the
wavy behavior of falling film has been conducted for Reynolds number 10-120 in the laminar-wavy regime at
three different inclination angles 15◦
, 30◦ and 45°
. The vertical distance of the high-voltage wire electrodes to
ground electrodes has been set to 14 mm. The liquid velocity, film thickness, and wave frequency have been
measured for non-electrified and electrified falling film, and their results have been evaluated with other
experimental studies and an acceptable agreement has been obtained. The results indicate that the proposed
HV wire-grounded plate electrode configuration in this study does not disturb the original structure of the
falling film and by intensifying the wavy behavior of laminar falling film can either suppress or enhance
heat/mass transfer rate. The effects of the applied voltage on the frequency, velocity and film thickness of the
falling liquid film have been also discussed in detail.
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