MODELLING OF FLUID TRANSIENTS IN VISCOELASTIC COMPLIANT PIPES

2021 ◽  
Author(s):  
Douglas Monteiro Andrade ◽  
Felipe Bastos de Freitas Rachid
Keyword(s):  
Fluid Transients

Fluid Transients

1977 ◽  
Vol 99 (2) ◽  
pp. 271-271
Author(s):  
C. Samuel Martin
Keyword(s):  
Fluid Transients

Development of a New Simulation Technique Based on the Modal Approximation for Fluid Transients in Complex Pipeline Systems With Time-Variant Nonlinear Boundary Conditions

2006 ◽  
Vol 129 (6) ◽  
pp. 791-798 ◽  
Author(s):  
E. Kojima ◽  
T. Yamazaki ◽  
M. Shinada
Keyword(s):  
Boundary Conditions ◽  
Nonlinear Boundary ◽  
Safety Valve ◽  
Nonlinear Boundary Conditions ◽  
Simulation Technique ◽  
Nonlinear Relationship ◽  
Calculation Methods ◽  
Pipeline Systems ◽  
Fluid Transients ◽  
Modal Approximation

A new simulation technique called the system modal approximation method (SMA) for fluid transients in complex pipeline systems has been proposed. The superiority of this technique compared to other existing methods has been verified. Thus far, however, detailed considerations have been limited to pipelines having elementary boundary conditions. In the present paper, for the generalization of the SMA method, calculation methods are newly proposed for the case in which the boundary conditions are given by the time-variant nonlinear relationship between pressure and flow rate, such as the conditions in a safety valve, and its usefulness is verified by comparison to experimental measurements.

Laminar Fluid Transients in Conduits of Arbitrary Cross Section

1995 ◽  
Vol 121 (10) ◽  
pp. 1069-1074 ◽  
Author(s):  
M. F. S. Letelier S. ◽  
H. J. Leutheusser ◽  
G. Márquez Z.
Keyword(s):  
Cross Section ◽  
Arbitrary Cross Section ◽  
Fluid Transients

Experimental Validation of Existing Numerical Models for the Interaction of Fluid Transients With In-Line Air Pockets

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Jane Alexander ◽  
Pedro J. Lee ◽  
Mark Davidson ◽  
Huan-Feng Duan ◽  
Zhao Li ◽  
...  
Keyword(s):  
Time Delay ◽  
Wave Speed ◽  
Numerical Models ◽  
Diagnostic Process ◽  
Air Pocket ◽  
Fluid Transients ◽  
Entrapped Air ◽  
Air Pockets ◽  
The Given ◽  
Potential Tool

Entrapped air in pipeline systems can compromise the operation of the system by blocking flow and raising pumping costs. Fluid transients are a potential tool for characterizing entrapped air pockets, and a numerical model which is able to accurately predict transient pressures for a given air volume represents an asset to the diagnostic process. This paper presents a detailed study on our current capability for modeling and predicting the dynamics of an inline air pocket, and is one of a series of articles within a broader context on air pocket dynamics. This paper presents an assessment of the accuracy of the variable wave speed and accumulator models for modeling air pockets. The variable wave speed model was found to be unstable for the given conditions, while the accumulator model is affected by amplitude and time-delay errors. The time-delay error could be partially overcome by combining the two models.

Rational Polynomial Transfer Function Approximations for Fluid Transients in Lines

2003 ◽  
Author(s):  
Patompong Wongputorn ◽  
David A. Hullender ◽  
Robert L. Woods
Keyword(s):  
Exact Solution ◽  
Transmission Lines ◽  
Transfer Functions ◽  
Viscous Friction ◽  
Total System ◽  
Nonlinear Frequency ◽  
Maximum Frequency ◽  
Rational Polynomial ◽  
Curve Fit ◽  
Fluid Transients

This paper introduces a simple approach utilizing MATLAB® computational tools for generating rational polynomial transfer functions for fluid transients in both liquid and gas fluid transmission lines. These transfer functions are obtained by curve fitting in the frequency domain the exact solution to the distributed parameter laminar flow “Dissipative Model” for fluid transients that includes nonlinear frequency dependent viscous friction terms as well as heat transfer effects in gas lines. These transfer functions are formulated so they are applicable to arbitrary line terminations and so they can be inserted directly into SIMULINK® models for time domain simulation and analysis of a total system of which the fluid lines are only internal components. The inputs to the algorithm are the internal radius and length of the line; the kinematic viscosity, density, Prandtl number, and speed of sound of the fluid; and the maximum frequency to which an accurate curve fit of the exact solution is desired. This maximum frequency normally is equal to or greater than the bandwidth of the other components in the total system to be analyzed or the maximum frequency associated with the input. The simplicity of use and accuracy in the results of the exact solution representations are demonstrated for examples of a blocked fluid line and of a line terminating into a tank. The computational algorithms are available for download from the Author’s web site. This is the first of two papers pertaining to transfer functions for fluid transients. The second paper pertains to formulating simulation diagrams for total systems containing fluid lines represented by rational polynomial transfer functions.

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