scholarly journals A Porous Media Leakage Model of Contact Mechanical Seals Considering Surface Wettability

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1338
Author(s):  
Guangyao Bei ◽  
Chenbo Ma ◽  
Jianjun Sun ◽  
Xingya Ni ◽  
Yafei Ma
Keyword(s):  
Contact Angle ◽  
Porous Media ◽  
Slip Length ◽  
Apparent Contact Angle ◽  
Leakage Rate ◽  
Surface Wettability ◽  
Mechanical Seals ◽  
Leakage Model ◽  
Proposed Model ◽  
Contact Mechanical

The fluid leakage channel found in contact mechanical seals belongs to the microchannel category. Thus, upon further inspection, the influence of surface wettability and other factors neglected in previous studies becomes obvious. The porous leakage model of contact mechanical seals considering the surface wettability presented in this paper was based on the Cassie model and slip theory. The variations of the microchannel slip length and the velocity under various wettability conditions were studied and the relationship between the slip length and the apparent contact angle was established. Moreover, using porous media theory, the theoretical model of the leakage rate in contact mechanical seals considers the surface wettability depending on various parameters. The observed parameters included the surface contact angle, sealing medium pressure, viscosity coefficient, fractal dimension, and maximum pore diameter. The simulation results obtained using the proposed model have shown that the leakage rate increases with the increase of the apparent contact angle. Particularly when the contact pressure is small, the influence of the surface wettability is more significant. Furthermore, the leakage rate results obtained via the proposed model were compared to those of existing models. The comparison confirmed that the proposed model is applicable and that the necessity of considering wettability significantly affects the leakage rate calculation accuracy. The proposed model lays a foundation for further improving the calculation accuracy, making it easier for both the researchers and practitioners to suppress the leakage in contact mechanical seals.

scholarly journals A Leakage Model of Contact Mechanical Seals Based on the Fractal Theory of Porous Medium

Coatings ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 20
Author(s):  
Xingya Ni ◽  
Chenbo Ma ◽  
Jianjun Sun ◽  
Yuyan Zhang ◽  
Qiuping Yu
Keyword(s):  
Porous Media ◽  
Fractal Dimension ◽  
Pore Diameter ◽  
Fractal Theory ◽  
Leakage Rate ◽  
Contact Interface ◽  
Mechanical Seals ◽  
The Real ◽  
Leakage Model ◽  
Contact Mechanical

A theoretical model for calculating the leakage rate of contact mechanical seals based on the fractal theory of the porous media, which can consider the real seal contact interface and objectively reflect the flow of the interfacial fluid from a microscopic perspective, is established. In order to obtain the microstructural parameters of the porous media included in the leakage model, such as the fractal dimension and the maximum pore diameter, the real seal contact interface obtained from experiments is reconstructed, a contact model between the dynamic and static rings is proposed, and then the calculation methods for the interface characteristic parameters are provided. Numerical simulation results show that as the contact pressure increases from 0.05 to 0.5 MPa, the interface porosity and the maximum pore diameter decreases gradually. Furthermore, the fractal dimension of the pore area increases and the leakage rate of the interface decreases from 0.48 to 0.33 mL/h. The proposed method provides a novel way of calculating the leakage rate of contact mechanical seals.

Influence of Surface Wettability on Dropwise Condensation Heat Transfer

2011 ◽  
Vol 228-229 ◽  
pp. 869-873
Author(s):  
Yun Fu Chen
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Surface Wettability ◽  
Condensation Heat Transfer ◽  
Size Distributions ◽  
Dropwise Condensation ◽  
Number Density ◽  
Drop Radius ◽  
Proposed Model ◽  
Drop Size Distributions

For finding influence of the surface wettability on dropwise condensation heat transfer, a model for dropwise condensation heat transfer has been established based on the drop size distributions and the heat transfer rate through a single drop with considering influence of contact angle to heat transfer. It has been shown based on the proposed model that up to a drop radius of 5μm, the rate of decrease in the drop population density is not as steep as the rate for a drop radius greater than 10μm, because coalescence between drops starts taking place. Varying the contact angle changes the drop distribution; higher the contact angle, lower the departing droplet size and large number density of small droplets. Heat flux first increases and then decreases with increasing contact angle under the temperature difference condition.

Effect of Water Temperature, pH Value, and Film Thickness on the Wettability Behaviour of Copper Surfaces Coated with Copper Using EB-PVD Technique

2019 ◽  
Vol 60 ◽  
pp. 124-141 ◽  
Author(s):  
Naser Ali ◽  
Joao Amaral Teixeira ◽  
Abdulmajid Addali
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Film Thickness ◽  
Water Temperature ◽  
Ph Value ◽  
Surface Wettability ◽  
Copper Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Static Contact

This research investigates the effect of surface roughness, water temperature, and pH value on the wettability behaviour of copper surfaces. An electron beam physical vapour deposition technique was used to fabricate 25, 50, and 75 nm thin films of copper on the surface of copper substrates. Surface topographical analysis, of the uncoated and coated samples, was performed using an atomic force microscopy device to observe the changes in surface microstructure. A goniometer device was then employed to examine the surface wettability of the samples by obtaining the static contact angle between the liquid and the attached surface using the sessile drops technique. Waters of pH 4, 7, and 9 were employed as the contact angle testing fluids at a set of fixed temperatures that ranged from 20°C to 60°C. It was found that increasing the deposited film thickness reduces the surface roughness of the as-prepared copper surfaces and thus causing the surface wettability to diverge from its initial hydrophobic nature towards the hydrophilic behaviour region. A similar divergence behaviour was seen with the rise in temperature of water of pH 4, and 9. In contrast, the water of pH 7, when tested on the uncoated surface, ceased to reach a contact angle below 90o. It is believed that the observed changes in surface wettability behaviour is directly linked to the liquid temperature, pH value, surface roughness, along with the Hofmeister effect between the water and the surface in contact.

scholarly journals Tuning the Surface Wettability of Cyclic Olefin Copolymer by Plasma Treatment and Graphene Oxide Deposition and Reduction

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2305
Author(s):  
Fadi Dawaymeh ◽  
Yawar Abbas ◽  
Maryam Khaleel ◽  
Anas Alazzam ◽  
Nahla Alamoodi
Keyword(s):  
Contact Angle ◽  
Plasma Treatment ◽  
Treatment Duration ◽  
Chemical Reduction ◽  
Surface Wettability ◽  
Oxygen Plasma Treatment ◽  
Microfluidic Channels ◽  
Cyclic Olefin Copolymer ◽  
Cyclic Olefin ◽  
Reduction Methods

Selective altering of surface wettability in microfluidic channels provides a suitable platform for a large range of processes, such as the phase separation of multiphase systems, synthesis of reaction controlled, nanoliter sized droplet reactors, and catalyst impregnation. Herein we study the feasibility to tune the wettability of a flexible cyclic olefin copolymer (COC). Two methods were considered for enhancing the surface hydrophilicity. The first is argon/oxygen plasma treatment, where the effect of treatment duration on water contact angle and COC surface morphology and chemistry were investigated, and the second is coating COC with GO dispersions of different concentrations. For enhancing the hydrophobicity of GO-coated COC surfaces, three reduction methods were considered: chemical reduction by Hydroiodic acid (HI), thermal reduction, and photo reduction by exposure of GO-coated COC to UV light. The results show that as the GO concentration and plasma treatment duration increased, a significant decrease in contact angle was observed, which confirmed the ability to enhance the wettability of the COC surface. The increase in hydrophilicity during plasma treatment was associated with the increase in surface roughness on the treated surfaces, while the increase during GO coating was associated with introducing oxygen-containing groups on the GO-coated COC surfaces. The results also show that the different reduction methods considered can increase the contact angle and improve the hydrophobicity of a GO-coated COC surface. It was found that the significant improvement in hydrophobicity was related to the reduction of oxygen-containing groups on the GO-coated COC modified surface.

scholarly journals Interfacial Behaviour in Ferroalloys: The Influence of Sulfur in FeMn and SiMn Systems

2021 ◽  
Author(s):  
Sergey Bublik ◽  
Sarina Bao ◽  
Merete Tangstad ◽  
Kristian Etienne Einarsrud
Keyword(s):  
Contact Angle ◽  
Interfacial Tension ◽  
Sessile Drop ◽  
Interfacial Properties ◽  
Apparent Contact Angle ◽  
Holding Time ◽  
Transfer Rates ◽  
Experimental Parameters ◽  
Interfacial Behaviour ◽  
Modelling Approach

AbstractThe present study has investigated the influence of sulfur content in synthetic FeMn and SiMn from 0 to 1.00 wt pct on interfacial properties between these ferroalloys and slags. The effect of experimental parameters such as temperature and holding time was evaluated. Interfacial interaction between ferroalloys and slags was characterized by interfacial tension and apparent contact angle between metal and slag, measured based on the Young–Laplace equation and an inverse modelling approach developed in OpenFOAM. The results show that sulfur has a significant influence on both interfacial tension and apparent contact angle, decreasing both values and promoting the formation of a metal-slag mixture. Despite the fact that sulfur was added only to the ferroalloys, most of sulfur is distributed into slag after reactions with the metal phase. Increasing the maximum experimental temperature in the sessile drop furnace also resulted in a decrease of both interfacial properties, resulting in higher mass transfer rates and intensive reactions between metal and slag. The effect of holding time demonstrated that after reaching equilibrium in FeMn-slag and SiMn-slag systems (both with and without sulfur), interfacial tension and apparent contact angle remain constant.

scholarly journals Molecular Dynamics Simulation of Wetting Behavior: Contact Angle Dependency on Water Potential Models

2021 ◽  
Vol 1 (1) ◽  
pp. 10
Author(s):  
Lukman Hakim ◽  
Irsandi Dwi Oka Kurniawan ◽  
Ellya Indahyanti ◽  
Irwansyah Putra Pradana
Keyword(s):  
Molecular Dynamics ◽  
Contact Angle ◽  
Liquid Droplet ◽  
Center Of Mass ◽  
Contact Angles ◽  
Surface Wettability ◽  
Dynamics Simulation ◽  
Potential Models ◽  
Surface Hydrophilicity ◽  
Dynamics Simulations

The underlying principle of surface wettability has obtained great attentions for the development of novel functional surfaces. Molecular dynamics simulations has been widely utilized to obtain molecular-level details of surface wettability that is commonly quantified in term of contact angle of a liquid droplet on the surface. In this work, the sensitivity of contact angle calculation at various degrees of surface hydrophilicity to the adopted potential models of water: SPC/E, TIP4P, and TIP5P, is investigated. The simulation cell consists of a water droplet on a structureless surface whose hydrophilicity is modified by introducing a scaling factor to the water-surface interaction parameter. The simulation shows that the differences in contact angle described by the potential models are systematic and become more visible with the increase of the surface hydrophilicity. An alternative method to compute a contact angle based on the height of center-of-mass of the droplet is also evaluated, and the resulting contact angles are generally larger than those determined from the liquid-gas interfacial line.

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