The Response of Pneumatic Transmission Lines to Step Inputs

1959 ◽  
Vol 81 (4) ◽  
pp. 578-583 ◽  
Author(s):  
C. B. Schuder ◽  
R. C. Binder
Keyword(s):  
Fluid Flow ◽  
Distributed System ◽  
Transmission Lines ◽  
Pressure Change ◽  
One Dimensional ◽  
Pressure Time ◽  
Pressure Changes ◽  
Theoretical Results ◽  
Line Following ◽  
Good Agreement

An equation was derived which describes the pressure-time relationship that occurs at the end of a dead-ended or volume-terminated pneumatic transmission line following a sudden pressure change at its input. The two partial differential equations which are solved are basic for transient fluid flow in pipes and analogous to the equations for transient electric current in lines without leakage. The derivation was based on a one-dimensional uniformly distributed system, small, reversible, adiabatic-pressure changes, and laminar flow. Experimental results obtained from tests on 3/8-in. and 1/4-in. tubing showed good agreement with the theoretical results.

Steady Compressible Flow through a Single Row of Radial Holes in the Wall of a Pipeline

1970 ◽  
Vol 12 (4) ◽  
pp. 248-258 ◽  
Author(s):  
G. H. Trengrouse
Keyword(s):  
Discharge Coefficient ◽  
Pressure Change ◽  
Single Row ◽  
One Dimensional ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Flow Through ◽  
Flow Theories ◽  
Good Agreement

Measured values of discharge coefficient for air flow through a single row of radial holes in the wall of a pipeline are reported, together with the values of pipe Mach numbers in the immediate vicinity of the holes. A wide range of pressure and area ratios are considered, the flow through the holes being either into or out of the pipe. It is shown that the effects on the measured values of both the pressure level at discharge from the holes and the air temperature are negligible. The agreement between the pressure change in the pipeline due to the holes, obtained experimentally, and that predicted by simple, one-dimensional flow theories is generally unsatisfactory. However, theoretical predictions of the jet efflux angles based on two-dimensional, incompressible, non-viscous flow arguments are in good agreement with those measured, but discrepancies do arise in the prediction of discharge coefficients.

Two-Dimensional Study of Heat Transfer and Fluid Flow in a Natural Convection Loop

1982 ◽  
Vol 104 (3) ◽  
pp. 508-514 ◽  
Author(s):  
A. Mertol ◽  
R. Greif ◽  
Y. Zvirin
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
A Priori ◽  
Two Dimensional ◽  
Transfer Coefficients ◽  
One Dimensional ◽  
Heat Transfer Coefficients ◽  
First Time ◽  
Good Agreement

A study has been made of the heat transfer and fluid flow in a natural convection loop. Previous studies of these systems have utilized a one-dimensional approach which requires a priori specifications of the friction and the heat-transfer coefficients. The present work carries out a two-dimensional analysis for the first time. The results yield the friction and the heat-transfer coefficients and give their variation along the loop with the Graetz number as a parameter. Comparison is also made with experimental data for the heat flux and good agreement is obtained.

scholarly journals NUMERICAL RESEARCH OF THE CHANGE OF REGIME FOR UNSTABLE MASS TRANSFER IN A TERNARY GAS MIXTURE HYDROGEN- NITRIC OXIDE-NITROGEN

2020 ◽  
Vol 72 (4) ◽  
pp. 112-116
Author(s):  
A.B. Kalimov ◽  
◽  
O.V. Fedorenko ◽  
V.N. Kossov ◽  
◽  
...  
Keyword(s):  
Mass Transfer ◽  
Finite Size ◽  
Pressure Change ◽  
Gas Mixture ◽  
Governing Equations ◽  
Diffusion Channel ◽  
Numerical Research ◽  
Pressure Changes ◽  
Matter Transfer ◽  
Good Agreement

On the basis of the software package "MathCad", by solving the Stefan-Maxwell diffusion equations, the evolution of the features of mass transfer in a three-component gas mixture, depending on pressure changes, has been numerically studied. In this analysis, the mixing process is studied in a vertical cylindrical channel of a finite size and at the isothermal conditions. The governing equations are solved at the boundary conditions assuming the absence of matter transfer through the walls of diffusion channel. Through the Rayleigh partial numbers, the influence of the pressure change on the behaviour of diffusion and convective flows is examined. The numerical results reveal that an increase in the pressure leads to a change of modes in ternary gas mixture. The present results are in good agreement with the existing experimental data.

APPLICATION OF ELASTIC MATERIALS IN PROTECTION FROM STRONG IMPACTS

2004 ◽  
Vol 18 (14) ◽  
pp. 1977-1990
Author(s):  
MASKOVIC D. LJILJANA ◽  
MOHORA EMILIJAN ◽  
TOSIC S. BRATISLAV ◽  
VUJOVIC R. RATKO
Keyword(s):  
Elastic Material ◽  
Short Pulse ◽  
Three Dimensional ◽  
Polymer Materials ◽  
Elastic Materials ◽  
One Dimensional ◽  
Spherical Surfaces ◽  
The Impact ◽  
Theoretical Results ◽  
Good Agreement

The analysis of the behavior of elastic material subject to strong short pulse impact has shown that only one-dimensional structures support the impact without destruction. Compact two- and three-dimensional structures are destroyed during the impact along circular lines and spherical surfaces. For that reason, web-like shields are proposed for the protection of man and equipment. Polymer materials are most suitable for the production of web-like shields since they are made of fibers and highly stress resistant. Theoretical results are experimentally tested and the good agreement with theory was found.

scholarly journals ESTUDIO EXPERIMENTAL Y TEÓRICO DE LA PROPAGACIÓN DE ONDAS A TRAVÉS DE ESTRUCTURAS PERIÓDICAS

Anales AFA ◽  
2010 ◽  
pp. 14-18
Author(s):  
A. Dolinko ◽  
B. J. Gómez ◽  
C. E. Repetto ◽  
C. R. Stia ◽  
R. Welti
Keyword(s):  
Band Gap ◽  
Periodic System ◽  
Normal Modes ◽  
Simple Device ◽  
Impedance Method ◽  
Simple Version ◽  
One Dimensional ◽  
Transmission Coefficients ◽  
Theoretical Results ◽  
Good Agreement

In this work, the acoustic band-gap of a one-dimensional and locally periodic system is studied by using a simple version of the impedance method. The system consists of a duct with modulated section. The normal modes and the transmission coefficients are calculated for a system with two or more repeated structures. It is shown that very selective bands are obtained at specific frequencies after a convenient choice of the periods of repetition. A very good agreement is found between theoretical results and the corresponding experimental ones obtained by using a simple device.

The Relation of Isallobaric Wind Components to the Change of Pressure over a Given Locality*

1941 ◽  
Vol 22 (3) ◽  
pp. 117-120
Author(s):  
I. Gringorten
Keyword(s):  
Practical Importance ◽  
Surface Friction ◽  
Pressure Change ◽  
Theoretical Treatment ◽  
Wind Component ◽  
Small Departure ◽  
Gradient Wind ◽  
The Right ◽  
Pressure Changes ◽  
Good Agreement

Non-Technical Summary Why cyclones deepen and fill up is one of the fundamental problems in meteorology that still largely resists theoretical treatment; but it is a matter of great practical importance because it does not seem that our daily forecasts will improve greatly until we find quantitative expressions for the factors leading to development as well as mere translation of pressure systems. Mr. Gringorten in this paper follows up a line of attack already laid down by several European investigators to see how well it may agree with reality. While he does not offer us a new principle the result is very interesting because he shows that the familiar conception of the isallobaric wind component, i.e. the small departure of the wind from the “gradient wind” which follows the isobars (except with surface friction), must play an important role in the pressure changes observed on the weather maps or the barograms every day. Qualitatively we have believed this for some time but Mr. Gringorten has computed the expected pressure change, from formulae proposed by Bjerknes and by Sutcliffe, for a particular time and place. This case was for the layers between 2000 and 8000 feet above Detroit between 7:30 p.m. Feb. 2 and 7:30 p.m. Feb. 3, 1940. The computed pressure change at 2000 feet was at the rate of 22.8 millibars in 12 hours but the observed change was only 5 mb. The practical meteorologist will not regard this as very good agreement but in view of the great difficulties in the theoretical treatment of such a problem the theoretician finds some consolation in that at least the computation gives results in the right direction. Of course, as Mr. Gringorten points out, it was obvious on Feb. 3 from the A. M. weather map that the pressure would fall at Detroit by that evening, and no one would suggest that the theory be used for forecasting.—R. G. S.

Pressure Transients in Hydraulic Pipelines

1969 ◽  
Vol 91 (3) ◽  
pp. 453-460 ◽  
Author(s):  
A. R. D. Thorley
Keyword(s):  
Boundary Conditions ◽  
Tube Wall ◽  
Equations Of Motion ◽  
Cylindrical Tube ◽  
Pressure Change ◽  
Water Hammer ◽  
Horizontal Pipe ◽  
Series Of Experiments ◽  
Pressure Changes ◽  
Theoretical Results

Equations of motion for a cylindrical tube containing a fluid are developed from a consideration of the forces and moments in the tube wall. These equations are solved for boundary conditions representing the situation where the fluid is flowing steadily through a horizontal pipe and a valve at the downstream end is closed instantaneously. The solution gives theoretical results for the usual water-hammer wave but also predicts the existence of a precursor wave. Expressions are derived for the velocities of propagation of both transients and their associated pressure changes. A comprehensive series of experiments has been carried out. Some interesting and probably unique results were obtained, which demonstrate the behavior of both transients. Measurements of velocity and pressure change have been made. The effect of axial restraint on the pipe is demonstrated.

Heart Rate Signal Decomposition

2000 ◽  
Vol 39 (02) ◽  
pp. 200-203
Author(s):  
H. Mizuta ◽  
K. Yana
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressure Change ◽  
Normal Subjects ◽  
Signal Decomposition ◽  
Large Individual ◽  
Heart Rate Fluctuations ◽  
Type Pattern ◽  
Signal Cancellation ◽  
Pressure Changes

Abstract:This paper proposes a method for decomposing heart rate fluctuations into background, respiratory and blood pressure oriented fluctuations. A signal cancellation scheme using the adaptive RLS algorithm has been introduced for canceling respiration and blood pressure oriented changes in the heart rate fluctuations. The computer simulation confirmed the validity of the proposed method. Then, heart rate fluctuations, instantaneous lung volume and blood pressure changes are simultaneously recorded from eight normal subjects aged 20-24 years. It was shown that after signal decomposition, the power spectrum of the heart rate showed a consistent monotonic 1/fa type pattern. The proposed method enables a clear interpretation of heart rate spectrum removing uncertain large individual variations due to the respiration and blood pressure change.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

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