scholarly journals Dynamic Wetting Behavior of Vibrated Droplets on a Micropillared Surface

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Zhi-hai Jia ◽  
Wei Lei ◽  
Hui-nan Yang ◽  
Gang Wang
Keyword(s):  
Model Calculation ◽  
Water Droplet ◽  
Vertical Vibration ◽  
Wetting Transition ◽  
Compression Process ◽  
Dynamic Wetting ◽  
Wetting Behavior ◽  
Cassie State ◽  
Wenzel State

The dynamical wetting behavior has been observed under vertical vibration of a water droplet placed on a micropillared surface. The wetting transition takes place under the different processes. In compression process, the droplet is transited from Cassie state to Wenzel state. The droplet undergoes a Wenzel-Cassie wetting transition in restoring process and the droplet bounces off from the surface in bouncing process. Meanwhile, the wetting and dewetting models during vibration are proposed. The wetting transition is confirmed by the model calculation. This study has potential to be used to control the wetting state.

Spontaneous transition of a water droplet from the Wenzel state to the Cassie state: a molecular dynamics simulation study

2015 ◽  
Vol 17 (45) ◽  
pp. 30533-30539 ◽  
Author(s):  
Jiadao Wang ◽  
Shuai Chen ◽  
Darong Chen
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Simulation Study ◽  
Water Droplet ◽  
Dynamics Simulation ◽  
Spontaneous Transition ◽  
Transition Mechanism ◽  
Cassie State ◽  
Wenzel State ◽  
Influencing Parameters

Spontaneous transition from the Wenzel to Cassie state is achieved, and the transition mechanism and influencing parameters are analyzed.

Conformal and non-conformal surface modification of honeycomb-patterned porous films via tunable Cassie–Wenzel transition

RSC Advances ◽  
2016 ◽  
Vol 6 (57) ◽  
pp. 52131-52136 ◽  
Author(s):  
Qi-Zhi Zhong ◽  
Xiang Yu ◽  
Ming-Xu Cui ◽  
Ling-Shu Wan ◽  
Zhi-Kang Xu
Keyword(s):  
Surface Modification ◽  
Wetting Transition ◽  
Porous Films ◽  
Robust Approach ◽  
Cassie State ◽  
Wenzel State

We describe here a facile and robust approach to conformal and non-conformal surface modification by tuning the wetting transition between the Wenzel state and the Cassie state.

Determination of dynamic wetting behavior using different methods

2020 ◽  
Vol 298 (6) ◽  
pp. 595-602
Author(s):  
Junchao Wang ◽  
Yijun Cao ◽  
Guosheng Li ◽  
Yingwei Wang ◽  
Shulei Li ◽  
...  
Keyword(s):  
Dynamic Wetting ◽  
Wetting Behavior

Influence of Water Droplet Size and Temperature on Wet Compression

2007 ◽  
Author(s):  
M. Bianchi ◽  
F. Melino ◽  
A. Peretto ◽  
P. R. Spina ◽  
S. Ingistov
Keyword(s):  
Gas Turbine ◽  
Water Droplet ◽  
Droplet Diameter ◽  
Axial Compressor ◽  
Combined Cycle ◽  
Water Evaporation ◽  
Air Cooling ◽  
Compression Process ◽  
Two Phase ◽  
Wet Compression

In the last years, among all different gas turbine inlet air cooling techniques, an increasing attention to fogging approach is dedicated. The various fogging strategies seem to be a good solution to improve gas turbine or combined cycle produced power with low initial investment cost and less installation downtime. In particular, overspray fogging and interstage injection involve two-phase flow consideration and water evaporation during compression process (also known as wet compression). According to the Author’s knowledge, the field of wet compression is not completely studied and understood. In the present paper, all the principal aspects of wet compression and in particular the influence of injected water droplet diameter and surface temperature, and their effect on gas turbine performance and on the behavior of the axial compressor (change in axial compressor performance map due to the water injection, redistribution of stage load, etc.) are analyzed by using a calculation code, named IN.FO.G.T.E. (INterstage FOgging Gas Turbine Evaluation), developed and validated by the Authors.

Effects of Wet Compression on the Flow Behavior of a Centrifugal Compressor: A CFD Analysis

2014 ◽  
Author(s):  
Anish Surendran ◽  
Heuy Dong Kim
Keyword(s):  
Flow Rate ◽  
Water Droplet ◽  
Evaporation Rate ◽  
Pressure Ratio ◽  
Phase Flow ◽  
Water Droplets ◽  
Compression Process ◽  
Two Phase ◽  
Wet Compression ◽  
Injection Ratio

Wet compression has been emerging as a prominent method for augmenting net power output from land based gas turbine engine. It is proven more effective than the conventional inlet cooling methods. In this method, fine water droplets are injected just upstream of the compressor impeller. These water droplets absorb the latent heat of evaporation during the compression process of gas-water droplet two-phase flow, consequently reducing the temperature rise. Many gas turbine engineers have performed the feasibility and usefulness studies on this wet compression, but physical understanding on the wet compression process is highly lacking, and related compression flow mechanism remains ambiguous. In the present study, a computational fluid dynamics method has been applied to investigate the wet compression effects on a low speed centrifugal compressor. A Langrangian particle tracking method was employed to simulate the air-water droplet two-phase flow. The power saving achieved with different injection ratio of water droplets has been calculated and it is found that significant saving can be obtained with a water droplet injection ratio of above 3%. The vapor mass fraction varies linearly along the streamwise direction, making the assumption for a constant evaporation rate is valid. With the increase in the injection ratio the polytropic index for compression is coming down. The diffuser pressure recovery has been improved significantly with the wet compression; while the total pressure ratio across the impeller does not improve much. Contrary to the expectation, the evaporation rate is found to be coming down with the increase in the compressor mass flow rate. It is observed that the operating point, at which the peak pressure ratio occurs, shift towards higher mass flow rate during wet compression due to the local recirculation region within the vaneless space between the impeller and diffuser.

scholarly journals SURFACE EVOLVER SIMULATIONS OF DROPS ON MICROPOSTS

2012 ◽  
Vol 23 (08) ◽  
pp. 1240013 ◽  
Author(s):  
MATTHEW L. BLOW ◽  
JULIA M. YEOMANS
Keyword(s):  
Free Energy ◽  
Arbitrary Shape ◽  
Liquid Surface ◽  
Superhydrophobic Surfaces ◽  
Surface Evolver ◽  
Horizontal Section ◽  
Good Convergence ◽  
Cassie State ◽  
Wenzel State ◽  
Solid Liquid

An important feature in the design of superhydrophobic surfaces is their robustness against collapse from the Cassie–Baxter configuration to the Wenzel state. Upon such a transition a surface loses its properties of low adhesion and friction. We describe how to adapt the Surface Evolver algorithm to predict the parameters and mechanism of the collapse transition on posts of arbitrary shape. In particular, contributions to the free energy evaluated over the solid–liquid surface are reduced to line integrals to give good convergence. The algorithm is validated for straight, vertical and inclined, posts. Numerical results for curved posts with a horizontal section at their ends show that these are more efficient in stabilizing the Cassie state than straight posts, and identify whether the interface first depins from the post sides or the post tips.

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