The theory of waves travelling on the core in a swirling liquid

1951 ◽  
Vol 205 (1083) ◽  
pp. 530-540 ◽  
Keyword(s):  
Surface Tension ◽  
Cross Section ◽  
Centrifugal Force ◽  
High Speed ◽  
Critical Length ◽  
The Core ◽  
Angular Velocities ◽  
The Waves ◽  
Minimum Velocity ◽  
Group Velocities

An examination is made of waves moving under centrifugal force and surface tension along the oore in a swirling liquid. The waves may be of varicose form in which the cross-section of the core remains circular, or they may be helical, giving the core the shape of a multithreaded screw. The relation is obtained between the lengths of the waves and their axial and angular velocities; at a critical length the waves possess a minimum velocity. The group velocities are determined, and are shown to be negative under certain conditions. It is found that waves can exist which move so slowly that they should be readily visible although the core may be revolving at high speed.

scholarly journals A review on nanofiber fabrication with the effect of high-speed centrifugal force field

2019 ◽  
Vol 14 ◽  
pp. 155892501986751 ◽  
Author(s):  
Zhi-Ming Zhang ◽  
Yao-Shuai Duan ◽  
Qiao Xu ◽  
Biao Zhang
Keyword(s):  
Surface Tension ◽  
Force Field ◽  
Centrifugal Force ◽  
Formation Process ◽  
Rotational Speed ◽  
High Speed ◽  
Solution Concentration ◽  
Solution Viscosity ◽  
Centrifugal Spinning ◽  
Solution Parameters

Among the traditional methods for nanofiber fabrication, their inherent defects limit their application in industry. This work presents a simple and novel spinning technology to fabricate nanofiber, which uses a high-speed rotary spinneret called high-speed centrifugal spinning. Unlike electrospinning, the electric field is not required, and it could fabricate nanofiber in bulk from melt or solution materials. This work introduces the mechanism principle and development of high-speed centrifugal spinning. Besides, the high-speed centrifugal spinning is compared with the traditional spinning methods. The jet movement and nanofiber formation process under the action of centrifugal force are explained in detail. The effects of equipment parameters and spinning solution parameters on final nanofiber morphology are presented. These parameters are controllable, they include rotational speed of spinneret, length and diameter of nozzle, spinning solution concentration, spinning solution viscosity and surface tension, and collection distance.

Experimental Investigation of Boundary Layer Instabilities on the Free Surface of Non-Turbulent Jet

2012 ◽  
Author(s):  
Matthieu A. Andre ◽  
Philippe M. Bardet
Keyword(s):  
Boundary Layer ◽  
Free Surface ◽  
High Speed ◽  
Particle Tracking Velocimetry ◽  
Capillary Waves ◽  
Wave Growth ◽  
Image Velocimetry ◽  
Planar Laser ◽  
Surface Visualization ◽  
The Waves

Shear instabilities induced by the relaxation of laminar boundary layer at the free surface of a high speed liquid jet are investigated experimentally. Physical insights into these instabilities and the resulting capillary wave growth are gained by performing non-intrusive measurements of flow structure in the direct vicinity of the surface. The experimental results are a combination of surface visualization, planar laser induced fluorescence (PLIF), particle image velocimetry (PIV), and particle tracking velocimetry (PTV). They suggest that 2D spanwise vortices in the shear layer play a major role in these instabilities by triggering 2D waves on the free surface as predicted by linear stability analysis. These vortices, however, are found to travel at a different speed than the capillary waves they initially created resulting in interference with the waves and wave growth. A new experimental facility was built; it consists of a 20.3 × 146.mm rectangular water wall jet with Reynolds number based on channel depth between 3.13 × 104 to 1.65 × 105 and 115. to 264. based on boundary layer momentum thickness.

Analysis of the Variable Cross-Section Duct and Straightening Device Geometry Effects on the Hydrogen Combustion Process

2021 ◽  
pp. 62-71
Author(s):  
O.V. Guskov ◽  
V.S. Zakharov ◽  
Minko
Keyword(s):  
Combustion Chamber ◽  
Cross Section ◽  
High Speed ◽  
Power Plants ◽  
Combustion Process ◽  
Variable Cross Section ◽  
Hydrogen Combustion ◽  
Variable Cross ◽  
Calculation Methods ◽  
Transition Channel

The development and research of high-speed aircrafts and their individual parts is an urgent scientific task. In the scientific literature there is information about the integral characteristics of aircrafts of this type, but there is no detailed consideration of such an important part as the transition channel between the air intake and the combustion chamber. The article considers several flow path configurations. The numerical simulation results of hydrogen combustion in the channels of variable cross section using a detailed kinetic mechanism are presented. Based on the analysis of the data obtained, the models of the transition channel and the combustion chamber showing the best characteristics were selected. The impulse and the fuel combustion efficiency are used as criteria for comparing the flow paths. The difference in the application of two calculation methods is described. The presented results and calculation methods can be used at the stage of computational research of the working processes in advanced power plants.

Free spheroidal vibrations of the earth at very long periods, Part I— Calculation of periods for several earth models

1963 ◽  
Vol 53 (3) ◽  
pp. 483-501 ◽  
Author(s):  
Leonard E. Alsop
Keyword(s):  
Inner Core ◽  
Computer Programs ◽  
Free Vibrations ◽  
Stoneley Waves ◽  
The Core ◽  
The Earth ◽  
Earth Models ◽  
Shear Modes ◽  
Phase And Group Velocities ◽  
Group Velocities

Abstract Periods of free vibrations of the spheroidal type have been calculated numerically on an IBM 7090 for the fundamental and first two shear modes for periods greater than about two hundred seconds. Calculations were made for four different earth models. Phase and group velocities were also computed and are tabulated herein for the first two shear modes. The behavior of particle motions for different modes is discussed. In particular, particle motions for the two shear modes indicate that they behave in some period ranges like Stoneley waves tied to the core-mantle interface. Calculations have been made also for a model which presumes a solid inner core and will be discussed in Part II. The two computer programs which were made for these calculations are described briefly.

The generation of waves by wind

1952 ◽  
Vol 215 (1122) ◽  
pp. 299-328 ◽  
Keyword(s):  
Ocean Waves ◽  
Irish Sea ◽  
North Coast ◽  
Empirical Relationships ◽  
The North ◽  
Component Wave ◽  
Wave Trains ◽  
The Irish Sea ◽  
The Waves ◽  
Group Velocities

This paper describes an investigation of the height and length of ocean waves and swell in relation to the strength, extent and duration of the wind in the generating area, and the subsequent travel of the swell through calm and disturbed water. The investigation is based on records of waves made on the north coast of Cornwall, in the Irish Sea and in Lough Neagh. It is a practical continuation of the work of Barber & Ursell (1948), who showed that the waves leaving the generating area behave as a continuous spectrum of component wave trains which travel independently with the group velocities appropriate to their periods. The spectral distribution of energy in the storm area is considered, and the relative amplitudes of the different components are deduced empirically under various wind conditions. The results indicate that the wave characteristics become practically independent of fetch after 200 to 300 miles, and that in the equilibrium condition the steepness of the highest waves is inversely proportional to the square root of the wind speed. Some theoretical foundation can be found for the form of the empirical relationships if it is assumed that the wind acts on each wave component independently, and that the sheltering coefficient used by Jeffreys is proportional to the wave steepness. The results provide a basis for making reasonably accurate predictions of waves and swell from meteorological charts and forecasts.

scholarly journals On the surface-tension of liquids investigated by the method of jet vibration

1907 ◽  
Vol 80 (535) ◽  
pp. 26-27 ◽  
Keyword(s):  
Surface Tension ◽  
Cross Section ◽  
Wave Length ◽  
Standing Waves ◽  
Exact Determination ◽  
Relative Measurements

1. According to Lord Rayleigh’s theory of jet-vibrations, measurement of the length of the standing waves and the velocity and cross-section of a jet, together with the density of the liquid, affords the necessary constants for the calculation of the surface-tension. Notwithstanding the great fundamental advantages of this method, it has only been used in very few cases, and only for relative measurements of the surface-tension. The explanation hereof is to be found in the great difficulties connected with the adequate exact determination of the wave-length, and cross-section or velocity of the jet. As none of the methods in use for the measurement of these quantities could be taken as satisfactory, the main object of this investigation has been to work out really good methods for them.

Effect of Tube Diameter on Flow Phenomena of Gas-Liquid Two-Phase Flow in Microchannels

2015 ◽  
Author(s):  
Hideo Ide ◽  
Eiji Kinoshita ◽  
Ryo Kuroshima ◽  
Takeshi Ohtaka ◽  
Yuichi Shibata ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Water Solution ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Tube Diameter ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena ◽  
The Waves

Gas-liquid two-phase flows in minichannels and microchannels display a unique flow pattern called ring film flow, in which stable waves of relatively large amplitudes appear at seemingly regular intervals and propagate in the flow direction. In the present work, the velocity characteristics of gas slugs, ring films, and their features such as the gas slug length, flow phenomena and frictional pressure drop for nitrogen-distilled water and nitrogen-30 wt% ethanol water solution have been investigated experimentally. Four kinds of circular microchannels with diameters of 100 μm, 150 μm, 250 μm and 518 μm were used. The effects of tube diameter and physical properties, especially the surface tension and liquid viscosity, on the flow patterns, gas slug length and the two-phase frictional pressure drop have been investigated by using a high speed camera at 6,000 frames per second. The flow characteristics of gas slugs, liquid slugs and the waves of ring film are presented in this paper.

Sign in / Sign up

Export Citation Format

Share Document