scholarly journals On the mechanism of droplet rolling and spinning in inclined hydrophobic plates in wedge with different wetting states

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bekir Sami Yilbas ◽  
Mubarak Yakubu ◽  
Abba Abdulhamid Abubakar ◽  
Hussain Al-Qahtani ◽  
Ahmet Sahin ◽  
...  
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Recording System ◽  
Experimental Results ◽  
Phase Contact ◽  
Droplet Motion ◽  
3D Space ◽  
Three Phase ◽  
Tangential Momentum ◽  
Recorded Data

AbstractA water droplet rolling and spinning in an inclined hydrophobic wedge with different wetting states of wedge plates is examined pertinent to self-cleaning applications. The droplet motion in the hydrophobic wedge is simulated in 3D space incorporating the experimental data. A high-speed recording system is used to store the motion of droplets in 3D space and a tracker program is utilized to quantify the recorded data in terms of droplet translational, rotational, spinning, and slipping velocities. The predictions of flow velocity in the droplet fluid are compared with those of experimental results. The findings revealed that velocity predictions agree with those of the experimental results. Tangential momentum generated, via droplet adhesion along the three-phase contact line on the hydrophobic plate surfaces, creates the spinning motion on the rolling droplet in the wedge. The flow field generated in the droplet fluid is considerably influenced by the shear rate created at the interface between the droplet fluid and hydrophobic plate surfaces. Besides, droplet wobbling under the influence of gravity contributes to the flow inside the rolling and spinning droplet. The parallel-sided droplet path is resulted for droplet emerging from the wedge over the dusty surface.

High-Resolution Measurements at Nucleate Boiling of Pure FC-84 and FC-3284 and Its Binary Mixtures

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Enno Wagner ◽  
Peter Stephan
Keyword(s):  
Binary Mixtures ◽  
High Speed ◽  
Contact Region ◽  
Infrared Camera ◽  
Nucleate Boiling ◽  
Heated Wall ◽  
Rear Side ◽  
Phase Contact ◽  
Pure Fluids ◽  
Three Phase

In a special boiling cell, vapor bubbles are generated at single nucleation sites on top of a 20μm thick stainless steel heating foil. An infrared camera captures the rear side of the heating foil for analyzing the temperature distribution. The bubble shape is recorded through side windows with a high-speed camera. Global measurements were conducted, with the pure fluids FC-84 and FC-3284 and with its binary mixtures of 0.25, 0.5, and 0.75mole fraction. The heat transfer coefficient (HTC) in a binary mixture is less than the HTC in either of the single component fluid alone. Applying the correlation of Schlünder showed good agreement with the measurements (1982, “Über den Wärmeübergang bei der Blasenverdampfung von Gemischen,” Verfahrenstechnik, 16(9), pp. 692–698). Furthermore, local measurements were arranged with high lateral and temporal resolution for single bubble events. The wall heat flux was computed and analyzed, especially at the three-phase-contact line between liquid, vapor, and heated wall. The bubble volume and the vapor production rate were also investigated. For pure fluids, up to 50–60% of the latent heat flows through the three-phase-contact region. For mixtures, this ratio is clearly reduced and is about 35%.

scholarly journals Thermocapillary rupture of a horizontal liquid layer on a silicon substrate

2019 ◽  
Vol 196 ◽  
pp. 00041
Author(s):  
Dmitry Kochkin ◽  
Valentin Belosludtsev ◽  
Veronica Sulyaeva
Keyword(s):  
Experimental Study ◽  
Contact Line ◽  
High Speed ◽  
Video Camera ◽  
Phase Contact ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
Three Phase ◽  
Breakdown Phenomenon ◽  
Dry Spot

This paper is an experimental study of thermocapillary breakdown phenomenon in a horizontal film of liquid placed on a silicon nonisothermal substrate. With the help of a high-speed video camera the speed of the three-phase contact line was measured during the growth of a dry spot.

High Speed Milling Vibration Surveillance with Optimal Spindle Speed Based on Optimal Speeds Map

2013 ◽  
Vol 597 ◽  
pp. 125-130 ◽  
Author(s):  
Krzysztof J. Kalinski ◽  
Marek A. Galewski ◽  
Michał R. Mazur
Keyword(s):  
Experimental Data ◽  
Computational Model ◽  
High Speed ◽  
End Milling ◽  
The Self ◽  
Experimental Results ◽  
Modal Parameters ◽  
Chatter Vibration ◽  
High Speed Milling ◽  
Milling Vibration

The paper presents the method of the surveillance of the self-excited chatter vibration. At first, the workpiece modal parameters are estimated based on experimental data which leads to verification of computational model. Then, for selected surface points optimal spindle speeds are calculated. By considering sufficient amount of points it is possible to build a map of optimal spindle speeds. Experimental results show that this map may be used effectively for eliminating chatter in case of the process of ball end milling of a curved flexible detail.

Solidification Front Velocity of Ternary Titanium-Aluminides

1995 ◽  
Vol 398 ◽  
Author(s):  
M. Wettlaufer ◽  
J. Laakmann
Keyword(s):  
Experimental Data ◽  
Temperature Measurement ◽  
Solidification Front ◽  
High Speed ◽  
Titanium Aluminides ◽  
Front Velocity ◽  
Experimental Results ◽  
Video System ◽  
High Speed Video ◽  
Bulk Undercooling

ABSTRACTTernary titanium-aluminides with compositions of Ti51Al47Fe2, Ti51A147Cr2 and Ti51Al47Mn2 were investigated with respect to the correlation of their solidification front velocity v and bulk undercooling ΔT. The observation of the solidification front during the recalescence event has been realized using a high speed video system capable of recording up to 12,000 pictures per second. The temperature measurement was carried out by pyrometry, avoiding contact with the sample. The comparison of the experimental data with the LKT-theory (Lipton, Kurz, Trivedi; [1]) refers to a primary (hcp) β-Ti solidification for undercoolings below ΔT≈ 130 K and primary (bcc) α-Ti solidification for ΔT≥ 130 K. For undercoolings ≥ 150 K the theory differs greatly from the experimental results.The maximum undercoolings achieved were 268 K (Ti51Al47Fe2), 285 K (Ti51Al47Cr2) and 280 K (Ti51Al47Mn2), corresponding to a solidification front velocity v ≈ 9-10 m/s for all alloys.

Study on the Traction Properties of a High-Speed Grease

2013 ◽  
Vol 645 ◽  
pp. 353-356 ◽  
Author(s):  
Bing Su ◽  
Long Pan ◽  
Bo Yuan Yang
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Traction Force ◽  
Rolling Bearing ◽  
Exponential Model ◽  
Rolling Speed ◽  
Experimental Results ◽  
Control Equipment ◽  
Traction Coefficient ◽  
And Control

LGLT2 grease is a newly developed lithium based grease used widely in small rolling bearing of instrument and control equipment at high speed.In this paper the curves of the traction coefficient against slide-to-roll ratio of LGLT2 film are measured on a high-speed ball-disc traction force tester under the conditions of the varying rolling speed from 20m/s to 40m/s and the varying load from 20N to 40N.The experimental results show that the grease LGLT2 performs well under above conditions,demonsrating lower traction coefficients with the increasing rolling speed. Both T-J model and an exponential model are employed to fit the experimental data. The results show that there are high consistencies between the experimental data and calculation values obtained from both models.

Analysis of Traction Behavior of the High-Speed Lubricating Grease 7007 by the Correctional T-J Model

2011 ◽  
Vol 121-126 ◽  
pp. 27-32
Author(s):  
Bo Yuan Yang ◽  
Gang Qiang Liu ◽  
Bing Su
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Traction Force ◽  
Experimental Results ◽  
Rheological Parameters ◽  
Test Rig ◽  
Lubricating Grease

The traction behavior of high-speed lubricating grease 7007 was tested on a self-made test rig. The changes of traction coefficients with velocity, temperature and load were got from the experimental results. The rheological parameters were received on the basis of experimental data. The formula of traction force of high-speed lubricating grease 7007 was based on the correctional T-J model. The result shows that the traction coefficients of high-speed lubricating grease 7007 based on correctional T-J mode agree well with the experimental data.

Effect of Surface Roughness on the Behavior of Bubbles Growing and Departing From a Heated Surface

2017 ◽  
Author(s):  
Navdeep S. Dhillon
Keyword(s):  
Surface Roughness ◽  
Contact Line ◽  
Bubble Growth ◽  
High Speed ◽  
Heated Surface ◽  
Scaling Analysis ◽  
Phase Contact ◽  
Bubble Behavior ◽  
Three Phase ◽  
Effect Of Surface

The phenomenon of bubble growth on a heated surface is of fundamental importance in many scientific and engineering applications, including boiling heat transfer. Although the growth of a homogeneous bubble in a pool of hot liquid is well understood, bubbles growing on hot solid surfaces involve evaporation from a three-phase contact line and therefore exhibit several peculiar features. One of these is the effect of surface texture and wetting properties on the size and timing of bubbles that form and depart from a uniformly heated surface. Here, we present pool boiling experimental results elucidating this important phenomenon. Using high-speed optical imaging, we perform a comparative study of the process of growth and departure of bubbles on plain and rough surfaces and explore the different factors that dictate this behavior. Using scaling analysis, we analyze the primary forces acting on a growing bubble and show that the effect of surface roughness on bubble behavior can be explained in terms of the dependence of these forces on the rate of bubble growth and in-turn on the rate of thin-film evaporation from the three-phase contact line of the bubble.

Effect of Nanoparticles on Forming Process of Bubbles in a Nanofluid

2009 ◽  
Author(s):  
Fengmin Su ◽  
Xuehu Ma ◽  
Jiabin Chen
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Ccd Camera ◽  
Experimental Results ◽  
Forming Process ◽  
Three Phase ◽  
Insight Into

An experimental investigation was conducted to determine the effect of nanoparticles on the forming process of bubbles in the gas-liquid-nanoparticle three-phase fluidization. In the experiment, a SiO2-water nanofluid was prepared without any surfactants, and the forming process of bubbles in the nanofluid was observed by the high-speed CCD camera. The experimental results show that the diameter of the formed bubble in the nanofluid is smaller 5% than that in water, and the frequency forming bubbles in the nanofluid is higher than that in water. The investigation can provide an insight into the functionary mechanism of the bubble forming process in the gas-liquid-nanoparticles nanofluids.

scholarly journals Droplet Rolling and Spinning in V-Shaped Hydrophobic Surfaces for Environmental Dust Mitigation

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3039
Author(s):  
Mubarak Yakubu ◽  
Bekir Sami Yilbas ◽  
Abba A. Abubakr ◽  
Hussain Al-Qahtani
Keyword(s):  
3D Printing ◽  
Water Droplet ◽  
High Speed ◽  
Recording System ◽  
Functionalized Silica ◽  
Plate Surface ◽  
Hydrophobic Surfaces ◽  
Droplet Motion ◽  
Rolling Velocity ◽  
Solution Crystallization

The motion of a water droplet in a hydrophobic wedge fixture was examined to assess droplet rolling and spinning for improved dust mitigation from surfaces. A wedge fixture composed of two inclined hydrophobic plates had different wetting states on surfaces. Droplet rolling and spinning velocities were analyzed and findings were compared with the experiments. A wedge fixture was designed and realized using a 3D printing facility and a high speed recording system was adopted to evaluate droplet motion in the wedge fixture. Polycarbonate sheets were used as plates in the fixture, and solution crystallization and functionalized silica particles coating were adopted separately on plate surfaces, which provided different wetting states on each plate surface while generating different droplet pinning forces on each hydrophobic plate surface. This arrangement also gave rise to the spinning of rolling droplets in the wedge fixture. Experiments were extended to include dust mitigation from inclined hydrophobic surfaces while incorporating spinning- and rolling droplet and rolling droplet-only cases. The findings revealed the wedge fixture arrangement resulted in spinning and rolling droplets and spinning velocity became almost 25% of the droplet rolling velocity, which agrees well with both predictions and experiments. Rolling and spinning droplet gave rise to parallel edges droplet paths on dusty hydrophobic surfaces while striations in droplet paths were observed for rolling droplet-only cases. Spinning and rolling droplets mitigated a relatively larger area of dust on inclined hydrophobic surfaces as compared to their counterparts corresponding to rolling droplet-only cases.

scholarly journals A Comparison Between Theoretical Prediction and Experimental Measurement of the Dynamic Behavior of Spur Gears

1992 ◽  
Author(s):  
Brian Rebbechi ◽  
B. David Forrester ◽  
Fred B. Oswald ◽  
Dennis P. Townsend
Keyword(s):  
Experimental Data ◽  
Computer Model ◽  
High Speed ◽  
Contact Region ◽  
Experimental Results ◽  
Average Error ◽  
Spur Gears ◽  
Gear Noise ◽  
Gear Teeth ◽  
Model Predictions

Abstract A comparison was made between computer model predictions of gear dynamic behaviour and experimental results. The experimental data were derived from the NASA gear noise rig, which was used to record dynamic tooth loads and vibration. The experimental results were compared with predictions from the Australian Defence Science and Technology Organisation Aeronautical Research Laboratory’s gear dynamics code, for a matrix of 28 load-speed points. At high torque the peak dynamic load predictions agree with experimental results with an average error of 5 percent in the speed range 800 to 6000 rpm. Tooth separation (or bounce), which was observed in the experimental data for light-torque, high-speed conditions, was simulated by the computer model. The model was also successful in simulating the degree of load sharing between gear teeth in the multiple-tooth-contact region.

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