Paper 24: A Study of Column Separation following Valve Closure in a Pipeline Carrying Aviation Kerosine

1969 ◽  
Vol 184 (7) ◽  
pp. 57-64 ◽  
Author(s):  
J. A. Swaffield
Keyword(s):  
Computer Program ◽  
Method Of Characteristics ◽  
Hyperbolic Partial Differential Equations ◽  
Valve Closure ◽  
Test Rig ◽  
Cavity Collapse ◽  
Upstream Side ◽  
Column Separation ◽  
Series Of Experiments ◽  
The Subject

The occurrence of column separation on the upstream side of a valve following valve closure has been the subject of a series of experiments on a test rig utilizing Concorde L56 alloy fuel piping and Esso Aviation Kerosine Specification 2494. A Fortran IV computer program based on the method of characteristics has been employed to solve the quasi-linear hyperbolic partial differential equations governing the propagation of transient pressures and to predict the duration of vapour cavities formed either at the valve or at any point in the pipeline. Comparison of computer and observed results indicates an accuracy within 3 per cent for the first peak following valve closure and for the duration of the vapour cavities, and within 10 per cent for the later pressure peaks following vapour cavity collapse.

Towards an Improved Understanding of Water-Hammer Column-Separation Due to Rapid Valve Closure

2010 ◽  
Author(s):  
H. A. Warda ◽  
Y. Elashry
Keyword(s):  
Transient Flow ◽  
Computer Software ◽  
Check Valve ◽  
Cavity Formation ◽  
Valve Closure ◽  
Time Step ◽  
Vapor Cavity ◽  
Cavity Collapse ◽  
Column Separation ◽  
Video Frames

Column separation phenomenon occurring downstream of a closing valve, simulating the closure of non-return/check valve downstream of pumps due to pump trip is simulated. An improved understanding of how cavity is opened, grows and collapses is supported by comparing numerical results with measured values and analyzing video frames. In the present study two models, discrete vapor cavity and gas cavity models, of column separation are compared for the modeling of column separation. Both models showed considerable degree of stability with variation of number of sections into which the pipe is divided. An experimental setup was built to provide the means of obtaining reliable experimental data for transient flow in viscoelastic pipes to verify the numerical model. Two valve closure schemes were tested using solenoid globe and ball valves. Video photographs of column separation during the vapor cavity formation, growth and collapse were processed and video films are transformed into frames using computer software. The video frames representing the cavity development and pressure measurements downstream of the valve are compared with corresponding cavity and pressure traces predicted by the model at each time step of the framing process at the same location. It was also shown that the characteristic of check valve closure scheme seriously affects the cavity formation and the extent of pressure surges due to cavity collapse.

A Study of the Influence of Air Release on Column Separation in an Aviation Kerosine Pipeline

1972 ◽  
Vol 186 (1) ◽  
pp. 693-703 ◽  
Author(s):  
J. A. Swaffield
Keyword(s):  
High Speed ◽  
Interface Velocity ◽  
Cavity Collapse ◽  
Column Separation ◽  
Wide Range ◽  
Cavity Boundary ◽  
Series Of Experiments ◽  
Event Times ◽  
Hot Film ◽  
Opening Phase

The occurrence of column separation on the downstream side of a valve in an aviation kerosine pipeline has been the subject of an investigation involving the method of characteristics to solve the partial differential equations governing the propagation of pressure transients. Particular attention has been paid to assessing the influence of air released from the fuel during the opening phase of the cavity and the cavity boundary equations have been modified accordingly. A series of experiments carried out on a test rig, utilizing L56 alloy fuel piping and other aircraft standard components and pumping aviation kerosine Specification 2494, has been employed to test the validity of the computing procedures developed. Comparison of the computed and observed results shows that the effect of released air is significant, but that it can be dealt with by including the partial pressure of any gas in the cavity in the equations governing cavity pressure and interface velocity. A wide range of tests indicate that the agreement between observed and predicted results for maximum and minimum pressures and event times following valve closure is at worst within 10 per cent. The predicted cavity collapse pressures are consistently above those observed. The velocity of the separated fuel column was measured, by means of a high speed camera, at 1000 frames/s and by a hot film probe and linearizer unit. The latter method proved successful, and should allow further work to be carried out on the measurement of velocity profiles during transient propagation.

Evaluation of the Method of Characteristics Applied to a Pressure Transient Analysis of the B.A.C./S.N.I.A.S. Concorde Refuelling System

1972 ◽  
Vol 186 (1) ◽  
pp. 509-518
Author(s):  
T. J. Doyle ◽  
J. A. Swaffield
Keyword(s):  
Transient Analysis ◽  
Method Of Characteristics ◽  
Pressure Variation ◽  
Valve Closure ◽  
Test Rig ◽  
Inlet Valve ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Aircraft System ◽  
Peak Pressures

The pressure transient analysis of the Concorde refuelling system is designed to predict pressure variation within the aircraft system during tank inlet valve closure on completion of refuelling and during an emergency isolation of the aircraft system from the refuelling supply. The comparison between the predicted and observed pressure variations, recorded on a full scale fuel system test rig, was found to be at worst, within 10 per cent, during tank inlet valve closures, although the programme underestimated some peak pressures. Closer agreement was achieved during emergency system isolation.

Research of the activity and viability of spermatozoa at different concentrations and proportions of diluents after incubation

2020 ◽  
pp. 88-95
Author(s):  
Svitlana Lobchenko ◽  
Tetiana Husar ◽  
Viktor Lobchenko
Keyword(s):  
Plasma Concentration ◽  
Incubation Time ◽  
Coefficient Of Variation ◽  
Incubation Medium ◽  
Wide Range ◽  
Series Of Experiments ◽  
The Subject ◽  
Boar Spermatozoa ◽  
Native Plasma ◽  
Better Than

The results of studies of the viability of spermatozoa with different incubation time at different concentrations and using different diluents are highlighted in the article. (Un) concentrated spermatozoa were diluented: 1) with their native plasma; 2) medium 199; 3) a mixture of equal volumes of plasma and medium 199. The experiment was designed to generate experimental samples with spermatozoa concentrations prepared according to the method, namely: 0.2; 0.1; 0.05; 0.025 billion / ml. The sperm was evaluated after 2, 4, 6 and 8 hours. The perspective of such a study is significant and makes it possible to research various aspects of the subject in a wide range. In this regard, a series of experiments were conducted in this area. The data obtained are statistically processed and allow us to highlight the results that relate to each stage of the study. In particular, in this article it was found out some regularities between the viability of sperm, the type of diluent and the rate of rarefaction, as evidenced by the data presented in the tables. As a result of sperm incubation, the viability of spermatozoa remains at least the highest trend when sperm are diluted to a concentration of 0.1 billion / ml, regardless of the type of diluent used. To maintain the viability of sperm using this concentration of medium 199 is not better than its native plasma, and its mixture with an equal volume of plasma through any length of time incubation of such sperm. Most often it is at this concentration of sperm that their viability is characterized by the lowest coefficient of variation, regardless of the type of diluent used, which may indicate the greatest stability of the result under these conditions. The viability of spermatozoa with a concentration of 0.1 billion / ml is statistically significantly reduced only after 6 or even 8 hours of incubation. If the sperm are incubated for only 2 hours, regardless of the type of diluent used, the sperm concentrations tested do not affect the viability of the sperm. Key words: boar, spermatozoa, sperm plasma, concentration, incubation, medium 199, activity, viability, rarefaction.

scholarly journals XIV. On the absorption of gases by solids

1881 ◽  
Vol 32 (212-215) ◽  
pp. 407-408
Keyword(s):  
Royal Society ◽  
Hydraulic Press ◽  
Careful Examination ◽  
Solid Matter ◽  
Chemical Action ◽  
High Pressure And Temperature ◽  
Solid Iron ◽  
Series Of Experiments ◽  
The Subject ◽  
Very High

During the progress of the investigations which I have from time to time had the honour of bringing under the notice of the Royal Society, I have again and again noticed the apparent disappearance of gases inclosed in vessels of various materials when the disappearance could not be accounted for upon the assumption of ordinary leakage. After a careful examination of the subject I found that the solids absorbed or dissolved the gases, giving rise to a striking example of the fixation of a gas in a solid without chemical action. In carrying out that most troublesome investigation, the crystalline separation of carbon from its compounds, the tubes used for experiment have been in nine cases out of ten found to be empty on opening them, and in most cases a careful testing by hydraulic press showed no leakage. The gases seemed to go through the solid iron, although it was 2 inches thick. A series of experiments with various linings were tried. The tube was electro-plated with copper, silver, and gold, but with no greater success. Siliceous linings were tried fusible enamels and glass—but still the' tubes refused to hold the contents. Out of thirty-four experiments made since my last results were published, only four contained any liquid or condensed gaseous matter after the furnacing. I became convinced that the solid matter at the very high pressure and temperature used must be pervious to gases.

SOME MICROBIOLOGICAL STUDIES OF TWO SPECIES OF APHIDS, APHIS FABAE SCOP. AND MACROSIPHUM PISI (HARRIS) (HEMIPTERA, HOMOPTERA: APHIDIDAE)

1963 ◽  
Vol 9 (1) ◽  
pp. 65-73 ◽  
Author(s):  
N. N. LeBlanc ◽  
A. J. Musgrave
Keyword(s):  
Aphis Fabae ◽  
General Body ◽  
Histological Sections ◽  
Beneficial Microorganisms ◽  
Series Of Experiments ◽  
The Subject

Since 1850, aphids have been regarded as harboring, in mycetomes, supposedly beneficial microorganisms which have, however, been the subject of some controversy. In the present study of the aphids Aphis jabae and Macrosiphum pisi, mycetomes were identified in histological sections; but it proved impossible to isolate or culture any mycetomal microorganisms. Moreover, in a series of experiments in which great attention was paid to refined aseptic techniques no microorganisms could be isolated from the general body cavities or alimentary tracts of the aphids, though simultaneous attempts to isolate microorganisms from weevils were successful.

Influence of velocity head on filling transients in a branched pipeline

2018 ◽  
Vol 35 (7) ◽  
pp. 2502-2513 ◽  
Author(s):  
Ling Wang ◽  
Fujun Wang ◽  
Bryan William Karney ◽  
Ahmad Malekpour ◽  
Zhengwei Wang
Keyword(s):  
Method Of Characteristics ◽  
Energy Equation ◽  
Transient Flow ◽  
Numerical Results ◽  
Velocity Head ◽  
Piezometric Head ◽  
Content Type ◽  
High Point ◽  
Hydraulic Transient ◽  
Column Separation

Purpose The velocity head is usually neglected in the energy equation for a pipeline junction when one-dimensional (1D) hydraulic transient flow is solved by method of characteristics. The purpose of this paper is to investigate the effect of velocity head on filling transients in a branched pipeline by an energy equation considering velocity head. Design/methodology/approach An interface tracking method is used to locate the air–water interface during pipeline filling. The pressured pipe flow is solved by a method of characteristics. A discrete gas cavity model is included to permit the occurrence of column separation. A universal energy equation is built by considering the velocity head. The numerical method is provisionally verified in a series pipeline and the numerical results and experimental data accord well with each other. Findings The numerical results show that some differences in filling velocity and piezometric head occur in the branched pipeline. These differences arise because the velocity head in the energy equation can become an important contributor to the hydraulic response of the system. It is also confirmed that a local high point in the profile is apt to experience column separation during rapid filling. Significantly, the magnitude of overpressure and cavity volume induced by filling transients at the local high point is predicted to increase with the velocity in the pipes. Originality/value The velocity head in the energy equation for a pipeline junction could play an important role in the prediction of filling velocity, piezometric head and column separation phenomenon, which should be given more attention in 1D hydraulic transient analysis.

scholarly journals XXIX. An account of some experiments to measure the velocity of electricity and the duration of electric light

1834 ◽  
Vol 124 ◽  
pp. 583-591 ◽  
Keyword(s):  
Electric Machine ◽  
Angular Motion ◽  
Continuous Line ◽  
Rapid Motion ◽  
Royal Institution ◽  
Series Of Experiments ◽  
The Subject ◽  
Electric Light ◽  
Rotatory Motion

The path of a luminous or an illuminated point in rapid motion, it is well known, appears as a continuous line, in consequence of the after duration of the visual im­pression. There is nothing, however, in the appearance of such a line by which the eye can determine either the direction or the velocity of the motion which generates it. It occurred to me some years since, that if the motion which described the line in these cases were to be compounded with another motion, the direction and velocity of which were known, it would be easy, from an inspection of the resultant straight or curved line, to determine the velocity and direction of the former. Following up this idea, I made a series of experiments relating to the oscillatory motions of sono­rous bodies, too numerous, and not sufficiently connected with the subject of the pre­sent communication, to be detailed in this place. The satisfactory results thus ob­tained made me desirous to ascertain whether, by similar means, some information might not be gained respecting the direction and velocity of the electric spark : the method by which I then proposed to effect this purpose was first announced in a lec­ture delivered by Dr. Faraday at the Royal Institution in June, 1830. My attention was again drawn to the subject at the commencement of last year, and I attempted to realize the idea in the following manner. Fig. 1 represents the apparatus employed, which was screwed at a to the spindle of a whirling machine, so that a rapid rotatory motion might be given to it. The upper and lower parts, which were all of brass except the wooden disc b c , were insulated from each other by a stout glass rod d e ; a slip of tinfoil connected the ball h with a , and the upper ball g was capable of adjustment to various distances from the lower one h . When the ball f was placed within striking distance of the prime conductor of an electric machine, a spark passed between them, and also between the balls g and h , which could be separated to the distance of four inches, so as to exhibit a spark of that length. It is obvious, that if the angular motion of the balls were in any sensible proportion to the velocity of electricity, there would be a deviation between the upper and lower terminations of the line. The instrument revolving from left to right, if the motion of the spark be downwards, the deflection of the line should be as in fig. 2; and if its motion be upwards, it should be deflected as in fig. 3.

scholarly journals LXI. An account of the phænomena of elec­tricity in vacuo, with some observations thereupon

1752 ◽  
Vol 47 ◽  
pp. 362-376 ◽  
Keyword(s):  
Series Of Experiments ◽  
The Subject

Gentlemen, In a paper I had the honour to lay before you in January 1747, which was the last I communicated to you of my own upon the subject of electricity, and which has been since publish'd in the Philos. Trans , I acquainted you, that I intended upon some future occasion to lay before you a series of experiments in electricity made in vacuo ;

Column Separation Accompanying Liquid Transients in Pipes

1967 ◽  
Vol 89 (4) ◽  
pp. 837-846 ◽  
Author(s):  
R. A. Baltzer
Keyword(s):  
Fluid Dynamics ◽  
Method Of Characteristics ◽  
Time Pressure ◽  
Experimental Information ◽  
Free Surface Flows ◽  
Energy Losses ◽  
Nonlinear Friction ◽  
Systems Of Equations ◽  
Surface Flows ◽  
Column Separation

Column separation is described and investigated in terms of the governing fluid dynamics. The partial differential equations of continuity and momentum, including nonlinear friction losses, are used to mathematically represent the transient movement of liquids in pipes under conditions of both full-pipe and free-surface flows. The complete systems of equations are programmed for numerical simulation of the column-separation phenomenon using a digital computer and the method of characteristics. Theoretical time-pressure information derived from mathematical simulation is compared with the corresponding experimental information obtained from laboratory investigation. Despite higher-than-anticipated energy losses in the prototype flow, the general comparison of the two sets of information is favorable.

Sign in / Sign up

Export Citation Format

Share Document