Dynamic Behavior of Liquid Mercury Droplets Colliding with a Solid Surface

2014 ◽  
Vol 566 ◽  
pp. 391-396
Author(s):  
Takashi Naoe ◽  
Masatoshi Futakawa
Keyword(s):  
Surface Tension ◽  
Dynamic Behavior ◽  
Solid Surface ◽  
High Speed ◽  
Droplet Diameter ◽  
High Surface ◽  
Quartz Plate ◽  
Bubble Collapse ◽  
Fundamental Study ◽  
Liquid Mercury

The dynamic behavior of liquid mercury and water droplets colliding with a solid surface were precisely examined as part of a fundamental study for investigating the behavior of a liquid microjet emitted as a result of a cavitation bubble collapse in mercury. Liquid droplets were collided with a quartz plate by the free-fall method, and the colliding and spreading behaviors of the liquids were observed using a high-speed video camera. In the case of mercury droplets, the spreading, recoiling, and jump-up phenomena resulting from the high surface tension of mercury were observed. The ratio of the maximum spreading diameter,Dmax, to the initial droplet diameter,D0, was investigated by parametrically changing the colliding velocity and tilt-angle of the quartz plate. The result showed that the ratioDmax/D0was well correlated with the Weber number, which is defined as a function of the colliding velocity and surface tension, independent of the liquid considered.

scholarly journals The effects of surface tension on the spreading ratio during the impact of multiple droplets onto a hot solid surface

2018 ◽  
Vol 197 ◽  
pp. 08016
Author(s):  
Rafil Arizona ◽  
Teguh Wibowo ◽  
Indarto Indarto ◽  
Deendarlianto Deendarlianto
Keyword(s):  
Surface Tension ◽  
Ethylene Glycol ◽  
Solid Surface ◽  
High Speed ◽  
Frame Rate ◽  
Stainless Steel Surface ◽  
Droplet Spreading ◽  
Secondary Droplets ◽  
The Impact ◽  
Maximum Spreading

The impact between multiple droplets onto hot surface is an important process in a spray cooling. The present study was conducted to investigate the dynamics of multiple droplet impact under various surface tensions. Here, the ethylene glycol with compositions of 0%, 5%, and 15% was injected through a nozzle onto stainless steel surface as the multiple droplet. The solid surface was heated at the temperatures of 100 °C, 150 °C, and 200 °C. To observe the dynamics of multiple droplets, a high speed camera with the frame rate of 2000 fps was used. A technique of image processing was developed to determine the maximum droplet spreading ratio. As the result, the surface tension contributes significantly to maximum spreading ratio. As the droplet surface tension decreases, the maximum spreading ratio increases. The maximum spreading ratio appears when the percentage of the ethylene glycol is 15% at the temperature of 150°C. From the visual observation, it is shown that a slower emergence of secondary droplets (droplet splashing) is carried out under a lower surface tension. Hence, surface tension plays an important role on the behavior of emerging secondary droplets. Furthermore, results of the experiments are useful for the validation of available previous CFD models.

Dynamic Behavior of a Small Water Droplet Impact Onto a Heated Hydrophilic Surface

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
El-Sayed R. Negeed ◽  
M. Albeirutty ◽  
Sharaf F. AL-Sharif ◽  
S. Hidaka ◽  
Y. Takata
Keyword(s):  
Dynamic Behavior ◽  
Water Droplet ◽  
High Speed ◽  
Heated Surface ◽  
Droplet Diameter ◽  
Video Camera ◽  
Surface Wettability ◽  
Hydrodynamic Characteristics ◽  
Small Water ◽  
Hot Surface

The aim of this study is to investigate the influence of the surface wettability on the dynamic behavior of a water droplet impacting onto a heated surface made of stainless steel grade 304 (Sus304). The surface wettability is controlled by exposing the surfaces to plasma irradiation for different time periods (namely, 0.0, 10, 60, and 120 s). The experimental runs were carried out by spraying water droplets on the heated surface where the droplet diameter and velocity were independently controlled. The droplet behavior during the collision with the hot surface has been recorded with a high-speed video camera. By analyzing the experimental results, the effects of surface wettability, contact angle between impacting droplet and the hot surface, droplet velocity, droplet size, and surface superheat on the dynamic behavior of the water droplet impacting on the hot surface were investigated. Empirical correlations are presented describing the hydrodynamic characteristics of an individual droplet impinging onto the heated hydrophilic surfaces and concealing the affecting parameters in such process.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

scholarly journals Air mediates the impact of a compliant hemisphere on a rigid smooth surface

Soft Matter ◽  
2021 ◽  
Author(s):  
Siqi Zheng ◽  
Sam Dillavou ◽  
John M. Kolinski
Keyword(s):  
Elastic Body ◽  
Elastic Properties ◽  
Impact Velocity ◽  
Solid Surface ◽  
High Speed ◽  
Smooth Surface ◽  
High Speed Imaging ◽  
The Impact ◽  
Rigid Smooth

When a soft elastic body impacts upon a smooth solid surface, the intervening air fails to drain, deforming the impactor. High-speed imaging with the VFT reveal rich dynamics and sensitivity to the impactor's elastic properties and the impact velocity.

High-Speed Atomic Force Microscopy for Studying the Dynamic Behavior of Protein Molecules at Work

2006 ◽  
Vol 45 (3B) ◽  
pp. 1897-1903 ◽  
Author(s):  
Toshio Ando ◽  
Takayuki Uchihashi ◽  
Noriyuki Kodera ◽  
Atsushi Miyagi ◽  
Ryo Nakakita ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Dynamic Behavior ◽  
High Speed ◽  
Force Microscopy ◽  
Atomic Force ◽  
Protein Molecules

Tracing surfactant transformation from cellular release to insertion into an air-liquid interface

2004 ◽  
Vol 286 (5) ◽  
pp. L1009-L1015 ◽  
Author(s):  
T. Haller ◽  
P. Dietl ◽  
H. Stockner ◽  
M. Frick ◽  
N. Mair ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cultured Cells ◽  
High Surface ◽  
Lamellar Body ◽  
Liquid Interface ◽  
Alveolar Type ◽  
Tensile Forces ◽  
Modify Surface ◽  
Fluorescence Imaging Microscopy ◽  
Air Liquid Interface

Pulmonary surfactant is secreted by alveolar type II cells as lipid-rich, densely packed lamellar body-like particles (LBPs). The particulate nature of released LBPs might be the result of structural and/or thermodynamic forces. Thus mechanisms must exist that promote their transformation into functional units. To further define these mechanisms, we developed methods to follow LBPs from their release by cultured cells to insertion in an air-liquid interface. When released, LBPs underwent structural transformation, but did not disperse, and typically preserved a spherical appearance for days. Nevertheless, they were able to modify surface tension and exhibited high surface activity when measured with a capillary surfactometer. When LBPs inserted in an air-liquid interface were analyzed by fluorescence imaging microscopy, they showed remarkable structural transformations. These events were instantaneous but came to a halt when the interface was already occupied by previously transformed material or when surface tension was already low. These results suggest that the driving force for LBP transformation is determined by cohesive and tensile forces acting on these particles. They further suggest that transformation of LBPs is a self-regulated interfacial process that most likely does not require structural intermediates or enzymatic activation.

Fundamental Study on Laser Interactions With Nanoparticles-Reinforced Metals—Part II: Effect of Nanoparticles on Surface Tension, Viscosity, and Laser Melting

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Chao Ma ◽  
Jingzhou Zhao ◽  
Chezheng Cao ◽  
Ting-Chiang Lin ◽  
Xiaochun Li
Keyword(s):  
Surface Tension ◽  
Surface Roughness ◽  
Thermophysical Properties ◽  
Melting Process ◽  
Laser Melting ◽  
Fundamental Study ◽  
Laser Polishing ◽  
Laser Manufacturing ◽  
Manufacturing Technologies ◽  
Laser Interactions

It is of great scientific and technical interests to conduct fundamental studies on the laser interactions with nanoparticles-reinforced metals. This part of the study presents the effects of nanoparticles on surface tension and viscosity, thus the heat transfer and fluid flow, and eventually the laser melting process. In order to determine the surface tension and viscosity of nanoparticles-reinforced metals, an innovative measurement system was developed based on the characteristics of oscillating metal melt drops after laser melting. The surface tensions of Ni/Al2O3 (4.4 vol. %) and Ni/SiC (3.6 vol. %) at ∼1500 °C were 1.39 ± 0.03 N/m and 1.57 ± 0.06 N/m, respectively, slightly lower than that of pure Ni, 1.68 ± 0.04 N/m. The viscosities of these Ni/Al2O3 and Ni/SiC MMNCs at ∼1500 °C were 13.3 ± 0.8 mPa·s and 17.3 ± 3.1 mPa·s, respectively, significantly higher than that of pure Ni, 4.8 ± 0.3 mPa·s. To understand the influences of the nanoparticles-modified thermophysical properties on laser melting, an analytical model was used to theoretically predict the melt pool flows using the newly measured material properties from both Part I and Part II. The theoretical analysis indicated that the thermocapillary flows were tremendously suppressed due to the significantly increased viscosity after the addition of nanoparticles. To test the hypothesis that laser polishing could significantly benefit from this new phenomenon, systematic laser polishing experiments at various laser pulse energies were conducted on Ni/Al2O3 (4.4 vol. %) and pure Ni for comparison. The surface roughness of the Ni/Al2O3 was reduced from 323 nm to 72 nm with optimized laser polishing parameters while that of pure Ni only from 254 nm to 107 nm. The normalized surface roughness reduced by nearly a factor of two with the help of nanoparticles, validating the feasibility to tune thermophysical properties and thus control laser-processing outcomes by nanoparticles. It is expected that the nanoparticle approach can be applied to many laser manufacturing technologies to improve the process capability and broaden the application space.

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