Thermal atomisation of a liquid drop after impact onto a hot substrate

2018 ◽  
Vol 842 ◽  
pp. 87-101 ◽  
Author(s):  
I. V. Roisman ◽  
J. Breitenbach ◽  
C. Tropea
Keyword(s):  
Experimental Study ◽  
Thermal Effects ◽  
Weber Number ◽  
Contact Time ◽  
Liquid Drop ◽  
Relevant Parameter ◽  
Complete Detachment ◽  
Regime Map ◽  
Dimensionless Heat Flux ◽  
Dimensionless Heat

This experimental study is focused on the mechanisms of thermal atomisation of a drop impacting onto a hot substrate. This phenomenon is characterised by the wetting and dewetting of the substrate, caused not by the rim dynamics, but induced by thermal effects. These thermal effects lead to the lamella evaporation, levitation and disintegration, generation of a vertical spray of fine droplets and consequently, drop breakup. A typical contact time of the drop before complete detachment is theoretically estimated. This estimation agrees very well with the experiments. It is shown that the Weber number, often used for describing splashing drops, is not a relevant parameter for thermal atomisation. Finally, a regime map is plotted, using a combination of the dimensionless contact time and the dimensionless heat flux at the substrate.

Experimental Study of Thermal Effects in the Sterilization of Disperse Systems

2001 ◽  
Vol 32 (4-6) ◽  
pp. 5
Author(s):  
A. A. Dolinsky ◽  
Yu. A. Shurchkova ◽  
B. I. Basok ◽  
T. S. Ryzhkova
Keyword(s):  
Experimental Study ◽  
Thermal Effects ◽  
Disperse Systems

Dynamics of Liquid Sheet Breakup in Splash Plate Atomization

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
G. Thunivumani ◽  
Hrishikesh Gadgil
Keyword(s):  
Solid Surface ◽  
Weber Number ◽  
Jet Impingement ◽  
Liquid Sheet ◽  
Force Balance ◽  
Impingement Angle ◽  
Wide Range ◽  
Perforated Sheet ◽  
Sheet Breakup ◽  
Regime Map

An experimental study was conducted to investigate the breakup of a liquid sheet produced by oblique impingement of a liquid jet on a plane solid surface. Experiments are carried out over a wide range of jet Weber number (80–6300) and various jet impingement angles (30 deg, 45 deg, and 60 deg) are employed to study the sheet dynamics. The breakup of a liquid sheet takes place in three modes, closed rim, open rim, and perforated sheet, depending upon the Weber number. The transitions across the modes are also influenced by the impingement angle with the transition Weber number reducing with increase in impingement angle. A modified regime map is proposed to illustrate the role of impingement angle in breakup transitions. A theoretical model based on force balance at the sheet edge is developed to predict the sheet parameters by taking the shear interaction between the sheet and the solid surface into account. The sheet shape predicted by the model fairly matches with the experimentally measured sheet shape. The breakup length and width of the sheet are measured and comparisons with the model predictions show good agreement in closed rim mode of breakup.

Thermal effects on GFRP rebars: experimental study and analytical analysis

2009 ◽  
Vol 43 (6) ◽  
pp. 775-788 ◽  
Author(s):  
Abdelmonem Masmoudi ◽  
Radhouane Masmoudi ◽  
Mongi Ben Ouezdou
Keyword(s):  
Experimental Study ◽  
Thermal Effects ◽  
Analytical Analysis ◽  
Gfrp Rebars

Computational and Experimental Study of Laser Microwelding Processes for Electronic Packaging

2001 ◽  
Author(s):  
Wei Han ◽  
Ryszard J. Pryputniewicz
Keyword(s):  
Experimental Study ◽  
Electronic Packaging ◽  
Thermal Effects ◽  
Resistance Welding ◽  
Alternative Methods ◽  
Number Of Components ◽  
Computational Data ◽  
Computational Methodology ◽  
Laser Microwelding

Abstract Advances in microelectronics depend on reliable packaging. As sizes of components decrease and number of components per package increases, demands on interconnections, or joining, of two parts, e.g., wire to tab, or tab to tab, increase rapidly. Since traditional joining techniques, such as resistance welding, may no longer produce satisfactory microinterconnections, alternative methods are being developed. One of such methods is based on laser microwelding. In this paper, we discuss fundamental processes involved in laser microwelding, outline a computational methodology to simulate thermal effects produced, describe facilities used, present results, and summarize correlations between the experimental and computational data for applications in electronic packaging.

scholarly journals Формирование и деформация капель жидкости в микроканалах

2020 ◽  
Vol 46 (15) ◽  
pp. 18
Author(s):  
Ф.В. Роньшин ◽  
Ю.А. Дементьев ◽  
Е.А. Чиннов
Keyword(s):  
Experimental Study ◽  
Flow Regime ◽  
Cross Section ◽  
Weber Number ◽  
Rectangular Cross Section ◽  
Critical Value ◽  
Drop Formation ◽  
Liquid Bridges ◽  
Liquid Moving ◽  
Side Walls

An experimental study of drop formation in narrow horizontal microchannels with rectangular cross section and a height from 50 to 150 micrometers was performed. It is shown that in these channels there is a new flow regime when drops moving along the microchannel, which are vertical liquid bridges. Three mechanisms of the formation of such drops are distinguished: the formation directly near the liquid nozzle, the separation of droplets from the liquid moving along the side walls of the channel, and due to the destruction of strongly deformed drops and horizontal liquid bridges. It was found that the deformation of drops increases with an increase in the Weber number. It is shown that when the first critical value of the Weber number is reached, the drops begin to deform, and when the second Weber number is reached, they break.

Numerical Simulation and Experimental Study on Thermal Effects of 2.94 μm Er:YAG Laser

2012 ◽  
Vol 32 (6) ◽  
pp. 0614002 ◽  
Author(s):  
杨经纬 Yang Jingwei ◽  
王礼 Wang Li ◽  
吴先友 Wu Xianyou ◽  
江海河 Jiang Haihe
Keyword(s):  
Numerical Simulation ◽  
Experimental Study ◽  
Thermal Effects ◽  
Er:Yag Laser

scholarly journals Characteristics of Steady and Transient Superfluid Transport for the Cooling of Superconducting Rotating Machines

2003 ◽  
Vol 9 (6) ◽  
pp. 427-436
Author(s):  
Thomas C. Chuang
Keyword(s):  
Heat Flux ◽  
Laminar Flow ◽  
Generalized Equation ◽  
Analytical Models ◽  
Rotating Machines ◽  
Transient Transport ◽  
Driving Time ◽  
Common Framework ◽  
Dimensionless Heat Flux ◽  
Dimensionless Heat

The unique properties of superfluid helium (He II) make it a very efficient cooling agent for superconducting rotating machines. Steady and transient transport characteristics and design formulas for the cooling of superconducting windings are enumerated in this article. Several superfluid transport analytical models and useful design equations are discussed: laminar flow; turbulent flow; and pure superfluid flow under steady-state and transient conditions. An effort was made to consolidate all analytical models and experimental results into a common framework. Under conditions of steady He II transport, a dimensionless heat flux numberNq, a dimensionless driving force numberN∇T, and a characteristic length where used so that a generalized equation could be derived to describe superfluid transport in any geometry. In the case of transient transport of He II, a dimensionless heat flux numberNq∗and a dimensionless driving time numberNtwere used so that a generalized equation could be derived to describe transient superfluid transport in laminar flow and turbulent regimes. Many experimental data were compiled to substantiate the analysis.

Experimental Study on Diesel Engine and Analysis the Spray Characteristics of Diesel and Biodiesel by Varying Injection Pressure

2014 ◽  
Vol 984-985 ◽  
pp. 932-937 ◽  
Author(s):  
Palani Raghu ◽  
M. Senthamil Selvan ◽  
K. Pitchandi ◽  
N. Nallusamy
Keyword(s):  
Experimental Study ◽  
Diesel Engine ◽  
Weber Number ◽  
Direct Injection ◽  
Cone Angle ◽  
Injection Pressure ◽  
Injection Velocity ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone

— The spray characteristic of the injected fuel is mainly depends upon fuel injection pressure, temperature, ambient pressure, fuel viscosity and fuel density. An experimental study was conducted to examine the effect of injection pressure on the spray was injected into direct injection (DI) diesel engine in the atmospheric condition. In Diesel engine, the window of 20 mm diameter hole and the transparent quartz glass materials were used for visualizing spray characteristics of combustion chamber at right angle triangle position. The varying Injection pressure of 180 - 240 bar and the engine was hand cranked for conducting the experiments. Spray characteristics for Jatropha oil methyl ester (JOME) and diesel were studied experimentally. Spray tip penetration and spray cone angle were measured in a combustion chamber of Direct Injection diesel engine by employing high speed Digital camera using Mie Scattering Technique and ImageJ software. The study shows the JOME gives longer spray tip penetration and smaller spray cone angle than those of diesel fuels. The Spray breakup region (Reynolds number, Weber number), Injection velocity and Sauter Mean Diameter (SMD) were determined for diesel and JOME. SMD decreases for JOME than diesel and the Injection velocity, Reynolds Number, Weber Number Increases for JOME than diesel.

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