Measurement of sheath characteristics in the presence of convection and ionization

1996 ◽  
Vol 74 (9-10) ◽  
pp. 671-675 ◽  
Author(s):  
R. M. Clements ◽  
J. R. Dawe ◽  
S. A. H. Rizvi ◽  
P. R. Smy
Keyword(s):  
Boundary Layer ◽  
Plasma Electron ◽  
Experimental Results ◽  
Ion Density ◽  
Current Voltage ◽  
Planar Grid ◽  
Theoretical Predictions ◽  
Flame Plasma ◽  
Theoretical Paper ◽  
Good Agreement

A flame plasma whose electron and (or) ion density can be varied over several orders of magnitude is constrained to flow perpendicular to a planar grid Langmuir probe. The probe is biased negative to the plasma, and the current–voltage characteristics and the thickness of the ion sheath formed at the probe are measured. The level of the electron and (or) ion density is set within a range at which the probe current due to thermal ionization throughout the sheath is comparable with the current of ions convected into the sheath. The experimental results are compared with the predictions of a recent theoretical paper that calculates the effect of recombination upon the characteristics of planar, cylindrical, and spherical probes with boundary layer sheaths. The theoretical predictions and experimental results for an idealized planar configuration show good agreement over wide ranges of variation of probe bias and plasma electron and (or) ion density. This verification of the theoretical planar electrode – perpendicular-flow model, which is the basis for all three boundary layer relations, is seen as providing strong backing for these relations, which have application to ionization measurements in various forms of recombinant plasma.

Explicit formulation for the axial collapse of a pipe during drilling

2010 ◽  
Vol 224 (8) ◽  
pp. 1547-1549
Author(s):  
A Almasi
Keyword(s):  
Closed Form ◽  
Plastic Hinge ◽  
Variable Length ◽  
Experimental Results ◽  
Displacement Curve ◽  
Explicit Formulation ◽  
Theoretical Predictions ◽  
Hinge Zone ◽  
Good Agreement

New closed-form expressions are introduced for ax-symmetric progressive axial collapse of pipes that use a plastic folding mechanism based on variable length of an active plastic hinge zone. A procedure for determination of a load—displacement curve of axial pipe collapse is presented. Theoretical predictions give a good agreement with the experimental results owing to the influence of presented new refinements.

Paper 31: Capsule-Pipeline Flow—A Theoretical Study

1969 ◽  
Vol 184 (7) ◽  
pp. 89-100
Author(s):  
V. K. Garg ◽  
G. F. Round
Keyword(s):  
Theoretical Study ◽  
Theoretical Solution ◽  
Experimental Results ◽  
Free Flow ◽  
Average Flow ◽  
Pipe System ◽  
Liquid Carrier ◽  
Pipeline Flow ◽  
Theoretical Predictions ◽  
Good Agreement

Theoretical predictions of the behaviour of various parameters governing the free flow of a single, very long, denser-than-liquid carrier, cylindrical capsule in a horizontal pipeline are reported in this paper. The study was carried out for average flow velocities of approximately 1–10 ft/s in pipes of diameters 4, 6, 12, and 24 in with diameter ratios varying from 0·9 to 0·99. While two liquid carriers—water and an oil ( μ = 10 cP and sp. gr. = 0·85)—were used, the eccentricity of the capsule-pipe system was fixed at 0·999. The theoretical solution was found to be in good agreement with the experimental results.

Floating Thin Sheet in Waves: Drift Force, Drift Velocity and Wave Damping

2002 ◽  
Author(s):  
Choung Mook Lee ◽  
Kwan Hyoung Kang
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Surface Layer ◽  
Free Surface ◽  
Drift Velocity ◽  
Wave Attenuation ◽  
Thin Sheet ◽  
Theoretical Predictions ◽  
Drift Force ◽  
Good Agreement

Wave driven force on a deformable but inextensible thin sheet is investigated analytically by taking into account the boundary layer beneath the sheet. Wave tank experiments are carried out to verify the theoretical predictions. Theoretical prediction of the drift force, drift velocity, and wave attenuation by the sheet are made. It is found that the drift velocity of a contaminated free surface is much greater than that of a clean free surface, and increase in the drift velocity is greater for the greater shear stress on the interface of the viscous surface layer and the water below. The theoretical and experimental results are found in good agreement.

The bursting of a charged cylindrical film

1972 ◽  
Vol 328 (1575) ◽  
pp. 529-539 ◽  
Keyword(s):  
Experimental Data ◽  
Finite Length ◽  
Experimental Results ◽  
Exact Calculation ◽  
Conducting Film ◽  
Half Wavelength ◽  
Theoretical Predictions ◽  
Long Cylinder ◽  
Good Agreement

This paper is a sequel to Sir Geoffrey Taylor’s study of the bursting of an electrified cylindrical conducting film. Taylor described experiments in which the voltages, at which the film becomes statically unstable, were observed for various lengths of film. These results were compared with the theoretical predictions for disturbances on an infinitely long cylinder having a wavelength equal to the length of film used. It is shown here that a transition in the mode of bursting from an axisymmetric whole wavelength mode to a lateral half wavelength mode is to be expected and that the experimental data conform with this transition. An exact calculation of the modes for a film of finite length is also given here and the resulting theoretical predictions of instability and bursting voltages are in very good agreement with the experimental results.

Using Superhydrophobic SU-8 Film as the Dielectric for Electrowetting-on-Dielectric

2018 ◽  
Vol 281 ◽  
pp. 604-609
Author(s):  
Yu Hao Piao ◽  
Wei Qiang Wang
Keyword(s):  
Contact Angle ◽  
Dielectric Layer ◽  
Superhydrophobic Surface ◽  
High Performance ◽  
Apparent Contact Angle ◽  
Experimental Results ◽  
Electrowetting On Dielectric ◽  
Dc Voltage ◽  
Theoretical Predictions ◽  
Good Agreement

In this paper, we study the electrowetting effect of superhydrophobic SU-8 film as the dielectric for Electrowetting-on-Dielectric (EWOD). The change of apparent contact angle (APCA) on superhydrophobic surface in electrowetting systems was measured and analyzed using a modified Lippmann-Yong equation. The variation of APCA between droplet and device surface under various DC voltage and AC voltage of different frequencies was fully experimented. The experimental results were in good agreement with the theoretical predictions. This study shows the potential of using superhydrophobic SU-8 film as the dielectric layer in high-performance EWOD devices.

Effect of Textures on the Nanomechanical Properties of Nanocrystalline Fe-50%Ni Foil

2006 ◽  
Vol 15-17 ◽  
pp. 923-928
Author(s):  
Jong Kweon Kim ◽  
Shi Hoon Choi ◽  
Yong Bum Park
Keyword(s):  
Elastic Modulus ◽  
Sample Thickness ◽  
Experimental Results ◽  
Nanoindentation Test ◽  
Specimen Thickness ◽  
Strong Decrease ◽  
Nanomechanical Properties ◽  
Texture Change ◽  
Theoretical Predictions ◽  
Good Agreement

The textures and nanomechanical properties of nanocrystalline Fe-50wt%Ni foil fabricated by using an electroforming method were investigated. The as-deposited texture was characterized by major <100>//ND and minor <111>//ND fibre components. Annealing of the as-deposited specimen resulted in the texture change that the <111>//ND fibre texture developed strongly with decreasing <100>//ND intensity. The elastic modulus and hardness were investigated by nanoindentation test, and these experimental results were compared with the theoretical predictions based on an elastic self-consistent (ESC) polycrystal model. Annealing led to an increase in the elastic modulus and a strong decrease in the hardness. At the low ratio of indentation depth to the specimen thickness, the theoretical predictions of the elastic modulus in the sample thickness direction showed a good agreement with experimental results.

THE E-PLANE RADIATION PATTERN OF SHORT ELECTROMAGNETIC HORNS OF LARGE APERTURE

1947 ◽  
Vol 25a (6) ◽  
pp. 315-321 ◽  
Author(s):  
G. A. Woonton ◽  
J. G. Tillotson
Keyword(s):  
Electromagnetic Field ◽  
Diffraction Pattern ◽  
Radiation Pattern ◽  
Wave Length ◽  
Angular Position ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electric Vector ◽  
Theoretical Predictions ◽  
Good Agreement

The relation between the power received by a short, rectangular, electromagnetic horn, and its angular position in a plane electromagnetic field can be calculated, for rotation in the plane of the electric vector, from ordinary optical theory by assuming that the aperture produces at the throat a Fresnel diffraction pattern appropriate to the angular position of the aperture. Experimental results for four horns of slant lengths 25, 50, 100, and 176 cm., but all of the same aperture, 10λ to a side at a wave length of 3.2 cm., are in good agreement with the theoretical predictions at angles up to [Formula: see text] radian from the axis, for slant lengths down to 50 cm. but not down to 25 cm.

Laminar Free Convection From a Downward-Projecting Fin

1968 ◽  
Vol 90 (1) ◽  
pp. 63-70 ◽  
Author(s):  
G. S. H. Lock ◽  
J. C. Gunn
Keyword(s):  
Boundary Layer ◽  
Free Convection ◽  
Prandtl Number ◽  
Experimental Program ◽  
Boundary Layer Problem ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement ◽  
Quiescent Fluid

A theoretical analysis of conduction through and free convection from a tapered, downward-projecting fin immersed in an isothermal quiescent fluid is presented. The problem is solved by assuming quasi-one-dimensional heat conduction in the fin and matching the solution to that of the convection system, which is treated as a boundary layer problem. For an infinite Prandtl number, solutions are derived which take the form of a power law temperature distribution along the fin. The effect of this power (n) on heat transfer, drag, and the corresponding boundary layer profiles is discussed. It is shown that n is independent of the fin profile and dependent on a single nondimensional group χ. The theoretical results for infinite Prandtl number are compared with corresponding results derived from previous work using a Prandtl number of unity. The effect of Prandtl number on the determination of n and consequently the fin effectiveness is found to be extremely small. The results of an experimental program are also presented. These consist of temperature profiles and the n — χ relation for different fin geometries and surrounding fluids. Comparison with the theoretical predictions reveals good agreement.

Hypersonic Laminar Heat Transfer and Boundary Layer Transition on Blunted Cones

1968 ◽  
Vol 19 (4) ◽  
pp. 301-316 ◽  
Author(s):  
N. B. Wood
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Adverse Pressure Gradient ◽  
Boundary Layer Transition ◽  
Flow Visualisation ◽  
Vertex Angle ◽  
Layer Transition ◽  
Pressure Distributions ◽  
Theoretical Predictions ◽  
Good Agreement

SummaryMeasurements have been made of laminar and transitional heat transfer rate distribution on a 15° semi-vertex angle, spherically blunted, cone at Mach numbers 8·6, 10·6 and 13·0. The laminar results are compared with theoretical predictions and good agreement is obtained with a modified form of the analysis due to Lees. Using a development of the correlation of pressure distributions previously obtained by the author, a new correlation of experimental and theoretical heat transfer results is suggested. The effect of nose bluntness on boundary layer transition has been observed both from flow visualisation and heat transfer results. It is suggested that the main factor causing nose bluntness to influence transition is the adverse pressure gradient which is induced.

Modeling of Direct Current Atmospheric Pressure Argon Discharge in Two-Dimensional

2014 ◽  
Vol 852 ◽  
pp. 597-601
Author(s):  
Xue Yun Huang ◽  
Ting Ting Zhang ◽  
Xi Zhang
Keyword(s):  
Atmospheric Pressure ◽  
Comsol Multiphysics ◽  
Plasma Properties ◽  
Electric Voltage ◽  
Ion Density ◽  
Atom Density ◽  
Dc Discharge ◽  
Current Voltage ◽  
Argon Discharge ◽  
Good Agreement

The finite element computational package COMSOL multiphysics were used to simulate a bar plate dc discharge in argon at atmospheric pressure. The basic plasma properties such as electron density, ion density, metastable atom density, electron temperature, electric voltage and electric field were studied. The current-voltage (I-V) characteristic of numerical model is in good agreement well with experimental data. This model is simple and insightful as a theoretical tool for argon atmospheric pressure discharges.

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