Analysis of water drop placed on hydrophobic and porous surface that vibrates high frequency

Vibration-induced drop atomization involves breaking liquids into small droplets using vibrational energy. This method has a wide range of other applications such as aerospace, electronics cooling, fabric drying, agriculture, pharmaceutical industry, medical field and industrial production. In this study, the behavior of water drops placed on hydrophobic and porous surfaces vibrating at high frequency was experimentally investigated. The aim of this study is to investigate the behavior of two different volumes of water drops placed on hydrophobic and meshed plates and to reveal the effects of plate properties on the atomization behavior. For this purpose, a brass plate was coated using a hydrophobic water repellent spray. In order to check the hydrophobic properties of the plate, the surface roughness was measured with a profilometer and the contact angle of the water drop on the hydrophobic surface was measured. The plates designed to have 80, 160 and 400 μm sized meshes were porosized by laser processing. The actual diameter dimensions of the mesh plate were measured with a microscope. For atomization experiments, a piezoelectric ceramic disc was attached to the bottom of the test plates and excited with a sine input voltage. The top view of the drop in contact with the plate surface was recorded with a video camera. From the recorded images, the projection area of the water drop with respect to time was measured with an image analysis program and presented as graphs. In addition to the experiments, the optimal frequency value for atomization of the brass plate forced by the piezoelectric disc was determined numerically by the finite element method and how this frequency value changes at different plate thicknesses was also simulated. In this thesis, the behavior of droplets on hydrophobic, porous and nonporous plates in two different volumes was demonstrated. It has been shown in this thesis that coatings with hydrophobic properties can increase the efficiency of water droplet atomization. According to the general results obtained, the speed of atomization increased as the pore size increased in porous plates. In the hydrophobic plate, faster atomization occurred compared to the non-hydrophobic plate. It was concluded that the water drop with large water volume was atomized later. In addition, numerical analysis is used to determine the response (acceleration, velocity and displacement) of the plate to the applied frequency. In this study, the frequency response is obtained depending on the geometrical properties of the plate. These results can be evaluated for the use of porous elements or hydrophobic surfaces in the field of water atomization, agriculture, chemistry, pharmaceutical industry, etc. where liquids need to be dispersed or sprayed. In addition, more advanced hydrophobic coating materials and techniques can be studied.