Experimental investigation of inclined liquid water jet flow onto vertically located superhydrophobic surfaces |
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Authors: | Ali Kibar Hasan Karabay K Süleyman Yi?it Ikrime O Ucar H Y?ld?r?m Erbil |
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Institution: | (1) Department of Mechanical Engineering, Kocaeli University, 41040 Kocaeli, Turkey;(2) Department of Chemical Engineering, Gebze Institute of Technology, 41400 Gebze, Kocaeli, Turkey |
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Abstract: | In this study, the behaviour of an inclined water jet, which is impinged onto hydrophobic and superhydrophobic surfaces, has
been investigated experimentally. Water jet was impinged with different inclination angles (15°–45°) onto five different hydrophobic
surfaces made of rough polymer, which were held vertically. The water contact angles on these surfaces were measured as 102°,
112°, 123°, 145° and 167° showing that the last surface was superhydrophobic. Two different nozzles with 1.75 and 4 mm in
diameters were used to create the water jet. Water jet velocity was within the range of 0.5–5 m/s, thus the Weber number varied
from 5 to 650 and Reynolds number from 500 to 8,000 during the experiments. Hydrophobic surfaces reflected the liquid jet
depending on the surface contact angle, jet inclination angle and the Weber number. The variation of the reflection angle
with the Weber number showed a maximum value for a constant jet angle. The maximum value of the reflection angle was nearly
equal to half of the jet angle. It was determined that the viscous drag decreases as the contact angle of the hydrophobic
surface increases. The drag force on the wall is reduced dramatically with superhydrophobic surfaces. The amount of reduction
of the average shear stress on the wall was about 40%, when the contact angle of the surface was increased from 145° to 167°.
The area of the spreading water layer decreased as the contact angle of the surface increased and as the jet inclination angle,
Weber number and Reynolds number decreased. |
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