On-demand Electrohydrodynamic Jetting of an Ethylene Glycol and Water Mixture—System of Controlled Picoliter Fluid Deposition

2021 ◽  
Author(s):  
J. F. Dijksman ◽  
U. Stachewicz
Keyword(s):  
Fluid Flow ◽  
Power Amplifier ◽  
Large Diameter ◽  
Electrical Circuit ◽  
Viscous Drag ◽  
Water Mixture ◽  
Electrical Field ◽  
On Demand ◽  
Flat Substrate ◽  
Set Up

On-demand electrohydrodynamic jetting also called electrohydrodynamic atomization (EHDA) is a method to jet small amounts of fluid out of a nozzle with a relatively large diameter by switching on and off an electrical field between the nozzle and the substrate. The total amount of volume deposited is up to 5 pL. The set-up consists of a vertically placed glass pipette with a small nozzle directed downward and a flat substrate placed close to the end of the nozzle. Inside the pipette, an electrode is mounted close to the entrance of the nozzle. The electrode is connected to a high voltage power amplifier. Upon switching on the electrical field, the apparent surface tension drops, the meniscus deforms into a cone and fluid starts to flow toward the nozzle deforming the meniscus. At a certain moment the cone reaches the Taylor cone dimensions and from its tip a jet emerges that decomposes into a stream of charged fL droplets that fly toward the substrate. This process stops when the pulse is switched off. After switching off, the meniscus returns slowly to its equilibrium position. The process is controlled by different time constants, such as the slew rate of the power amplifier and the RC time of the electrical circuit composed of the electrical resistance in the fluid contained in the nozzle between the electrode and the meniscus, and the capacitance of the gap between the meniscus and the flat substrate. Another time constant deals with the fluid flow during the growth of the meniscus, directly after switching on the pulse. This fluid flow is driven by hydrostatic pressure and opposed by a viscous drag in the nozzle. The final fluid flow during droplet formation is governed by the balance between the drag of the charge carriers inside the fluid, caused by the current associated with the charged droplets leaving the meniscus and the viscous drag. These different phenomena will be discussed theoretically and compared to experimental results.

Wounds Week 2: 1–5 February 2021

2021 ◽  
Vol 30 (3) ◽  
pp. 213-221
Keyword(s):  
Wound Care ◽  
Care Community ◽  
On Demand ◽  
Registration Process ◽  
Question And Answer ◽  
To Come ◽  
Set Up ◽  
The University ◽  
Difficult Times

On 1 February, Journal of Wound Care and the University of Huddersfield streamed the first of the live webinars on their Wounds Week channel ( www.woundsweek.com ). All sessions are now available to watch on-demand. With highly innovative topics, Wounds Week 2 gives a chance for the wound care community to come together in these difficult times and engage in key education, free of charge. The sessions had live question and answer sessions; participants asked questions of the experts, making them a key part of the event. The registration process takes just a minute. There's nothing to install or set up—simply register and fill out your details. Follow on twitter at #WoundsWeek

Quadratic Mixed Convection Stagnation-Point Flow in Hydromagnetic Casson Nanofluid over a Nonlinear Stretching Sheet with Variable Thermal Conductivity

2021 ◽  
Vol 409 ◽  
pp. 95-109
Author(s):  
Ephesus Olusoji Fatunmbi ◽  
Samuel Segun Okoya
Keyword(s):  
Thermal Conductivity ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Stagnation Point ◽  
Stretching Sheet ◽  
Ohmic Heating ◽  
Nonlinear Partial Differential Equations ◽  
Viscous Drag ◽  
Casson Nanofluid ◽  
Nonlinear Stretching

An analysis of nonlinear mixed convection transport of hydromagnetic Casson nanofluid over a nonlinear stretching sheet near a stagnation point is deliberated in this study. The flow is confined in a porous device in the presence of thermophoresis, Ohmic heating, non-uniform heat source with temperature-dependent thermal conductivity associated with haphazard motion of tiny particles. The transport equations are translated from nonlinear partial differential equations into ordinary ones via similarity transformation technique and subsequently tackled with shooting method coupled with Runge-Kutta Fehlberg algorithm. The significant contributions of the embedded parameters on the dimensionless quantities are graphically depicted and deliberated while the numerical results strongly agree with related published studies in the limiting conditions. It is found that a rise in the magnitude of Casson fluid parameter decelerates the fluid flow while enhancing the viscous drag and thermal profiles. The inclusion of the nonlinear convection term aids fluid flow whereas heat transfer reduces with growth in the thermophoresis and Brownian motion terms.

Experimental Research on Drag Torque for Single-plate Wet Clutch

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Hu Jibin ◽  
Peng Zengxiong ◽  
Wei Chao
Keyword(s):  
Contact Angle ◽  
Surface Tension Force ◽  
Transmission Efficiency ◽  
Viscous Drag ◽  
Drag Torque ◽  
Two Phase ◽  
Rotating Speed ◽  
Single Plate ◽  
Wet Clutch ◽  
Set Up

The relative motion between the friction and separate plates in a disengaged wet clutch causes viscous drag torque when the lubrication fluid flows through the clearance. Reduction of the drag torque is one of the important potentials for the improvement of transmission efficiency. The objective of this study is to set up an experimental rig to measure drag torque for a single-plate wet clutch. Visualization of the flow pattern in the clearance through transparent quartz was presented. Design factors and lubrication conditions were tested to evaluate the effects on drag torque. A comparison between the nongrooved plate and grooved plate was made. Plates made up of different materials were also tested to reveal the effects caused by the contact angle. Drag torque increases linearly at low rotating speeds and gradually decreases at high rotating speeds. It is confirmed that fluid completely covers the plate surface at a low rotating speed and air mixes with the fluid at a high rotating speed. A low feeding flow rate is useful to reduce drag torque. The reduction of the drag torque benefits from radial and deep grooves compared to a flat plate. A small contact angle near the stationary plate plays an important role in maintaining the oil film, however, it has little effect on the drag torque at the rotating side because the hydrodynamic force becomes dominant compared to the surface tension force. The test results help to build an accurate mathematical model based on two-phase flow lubrication.

Growth of Large Diameter 4H-SiC by TSSG Technique

2013 ◽  
Vol 740-742 ◽  
pp. 65-68 ◽  
Author(s):  
Kazuhiko Kusunoki ◽  
N. Yashiro ◽  
Nobuhiro Okada ◽  
Kouji Moriguchi ◽  
Kazuhito Kamei ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fluid Flow ◽  
Single Crystal ◽  
Large Diameter ◽  
High Growth ◽  
High Growth Rate ◽  
Solution Growth ◽  
Morphological Stability ◽  
Control Member ◽  
Top Seeded Solution Growth

4H-SiC single crystal with 3-inch diameter was grown by top seeded solution growth (TSSG) technique. We used a new convection control member called “Immersion Guide (IG)” which causes the high and homogenous fluid flow in the solution. As a result, we achieved relatively high growth rate and morphological stability

Enhancement of the Completion Efficiency of Perforation Tunnels in Petroleum Wells

2006 ◽  
Author(s):  
M. A. Rahman ◽  
T. Heidrick ◽  
B. Fleck ◽  
M. Koksal
Keyword(s):  
Fluid Flow ◽  
Conventional Method ◽  
Differential Pressure ◽  
Triaxial Testing ◽  
Flow Rates ◽  
Different Types ◽  
Set Up ◽  
Petroleum Wells ◽  
Perforated Completion ◽  
The Ideal

The objective of perforating is to maximize well productivity by establishing good connectivity between the wellbore and formation. The conventional method of perforation — perforation by shooting (PS) — cannot achieve expected wellbore productivity due to a region of reduced permeability around the perforation tunnel. In this study, it has been established that permeability is decreased in the range of 30%–75% due to the implementation of the PS technique compared to the openhole completion. As a result, a new perforation technique — perforation by drilling (PD) — has been proposed in this paper. To simulate a perforated completion, cylindrical sand samples (0.0572 in OD) consolidated with cement with varying porosity were prepared. These samples were perforated (0.0136 m ED) by the PS, PD and Casting techniques. Perforations created by the Casting techniques are considered the ideal, openhole perforation tunnel. Fluid flow rates and differential pressure across the perforated samples were measured for three different types of samples using “Geotechnical Digital System” triaxial testing set-up. Fluid flow rates with changing differential pressure and finally pressure build-up data with time indicates the PD technique can achieve better wellbore productivity compared to the PS technique. Results indicate that at 100 kPa differential pressure the PS, PD and Casting techniques can achieve 0.20 mL/s, 0.65 mL/s and 1.00 mL/s fluid flow rates respectively across a sample.

scholarly journals Experimental analysis of Scheffler reflector water heater

2011 ◽  
Vol 15 (3) ◽  
pp. 599-604 ◽  
Author(s):  
Rupesh Patil ◽  
Gajanan Awari ◽  
Mahendra Singh
Keyword(s):  
Storage Tank ◽  
Large Diameter ◽  
Average Power ◽  
Water Heater ◽  
Average Value ◽  
Water Boiling Test ◽  
Maximum Water Temperature ◽  
Maximum Water ◽  
Set Up ◽  
And Storage

The performance of Scheffler reflector has been studied. In this system storage reservoir was installed at Focus point. It has a single large diameter drum which serves the dual purpose of absorber tube and storage tank. The drum is sized to have a storage capacity of 20 liter for experiment. The tests were carried out with this set up and were repeated for several days. Performance analysis of the collector has revealed that the average power and efficiency in terms of water boiling test to be 1.30 kilowatts and 21.61 % respectively against an average value of beam radiations of 742[Wm-2]. The maximum water temperature in the storage tank of 98?C has been achieved on a clear day operation and ambient temperature between 28?C to 31?C.

Study on Magnetic Fluid Static Seal of Large Gap

2012 ◽  
Vol 512-515 ◽  
pp. 1448-1454 ◽  
Author(s):  
De Cai Li ◽  
Hai Na Zhang ◽  
Zhi Li Zhang
Keyword(s):  
Magnetic Field ◽  
Theoretical Analysis ◽  
Saturation Magnetization ◽  
Magnetic Fluid ◽  
Large Diameter ◽  
Burst Pressure ◽  
The Past ◽  
Set Up ◽  
Experimental Rig ◽  
Theoretical Results

Researchers have been studying the magnetic fluid seal of small gap in the past. In order to meet the static seal requirements of large gap in aviation, aerospace, metallurgy, and so on. We set up the experimental rig of magnetic fluid static seal and designed the static seal of magnetic fluid. In the experimental rig, we studied the static seal of magnetic fluid and obtained the relationships among the burst pressure and the amount of injection of magnetic fluid, seal gap, temperature and magnetization in the experimental rig. In theory, we calculated the distribution of magnetic field under the seal gap and reasoned sustained pressure and temperature and calculated the burst pressure in different gaps and different saturation magnetization. We analyzed the experimental and theoretical results in detail. The theoretical analysis and tests indicated that magnetic fluid seal of large gap and large diameter can sustain a definite pressure and meet the requirements of practical problems.

Dynamic Deployment of Smart Inflatable Tsunami Airbags (TABs) for Tsunami Disaster Mitigation

2015 ◽  
Author(s):  
M. Shahinpoor ◽  
H. Asanuma
Keyword(s):  
Tsunami Wave ◽  
Disaster Mitigation ◽  
Viscous Drag ◽  
Tsunami Waves ◽  
Tsunami Disaster ◽  
Air Bags ◽  
Pass Through ◽  
Set Up ◽  
The Impact ◽  
Inflatable Structure

Presented is an initial discussion on dynamic simulation of tsunami air bag deployment in connection with a number of smart inflatable and deployable structures, called tsunami air bags (TAB) that can be rather quickly set up and strongly anchored to the ocean floor to withstand the impact of a tsunami wave and thus protect the buildings and structures on shore. These dedicated inflatable smart structures are designed such that upon tsunami impact they can perform two smart deployment tasks. The first one is for the structure to deploy in the form of a porous structure containing internal folds and pockets and reconfigure due to tsunami impact to perform energy absorption by forcing the tsunami waves to pass through the porous inflatable structure forcing the tsunami waves to lose kinetic energy due to viscous drag and pressurizing the TABs. The second task is related to a special de sign of the inflatable structure that causes it to deploy to either further vertically rise or become a hollow inflatable dam upon the tsunami impact. In these endeavors a wave generation channel was designed and constructed to perform experiments and to simulate tsunami wave impacts on inflatable structures deploying from an underwater location. The initial observation indicates that TABs have a great potential to mitigate tsunami impacts.

Housing Influence on Churning Losses in Geared Transmissions

2007 ◽  
Author(s):  
C. Changenet ◽  
P. Velex
Keyword(s):  
Fluid Flow ◽  
Qualitative Evaluation ◽  
Flow Regimes ◽  
Power Losses ◽  
Test Rig ◽  
Automotive Transmission ◽  
Transmission Geometry ◽  
Analytical Formulas ◽  
Set Up ◽  
Fluid Flow Regimes

In a previous paper, a series of analytical formulas were presented enabling accurate predictions of churning losses for one gear which is typical of automotive transmission geometry. However, this formulation does not take into account the influence of flanges and deflectors. In order to extend the proposed methodology, a test rig has been set up in which several moveable walls can be inserted thus making it possible to modify the radial and axial clearances, i.e., the distances between the tested gear and the walls. Based on a qualitative evaluation of the various fluid flow regimes possible in gearboxes, the influence of the global volume of the oil sump on churning losses is analyzed. By considering a number of flange and deflector arrangements, the following conclusions are drawn: a) radial clearances have a weaker influence than axial clearances and, b) power losses can be minimized by properly chosen axial clearances.

Metal-free catalytic hydrogen production from a polymethylhydrosilane–water mixture

RSC Advances ◽  
2016 ◽  
Vol 6 (7) ◽  
pp. 5903-5906 ◽  
Author(s):  
Chew Pheng Yap ◽  
Hwa Tiong Poh ◽  
Wai Yip Fan
Keyword(s):  
Free Energy ◽  
Hydrogen Production ◽  
Hydrogen Gas ◽  
Energy Carrier ◽  
Water Mixture ◽  
Metal Free ◽  
On Demand ◽  
Formidable Challenge ◽  
Catalytic Hydrogen

Hydrogen gas is the most promising carbon-free energy carrier although its on-demand generation remains a formidable challenge.

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