Computer Aided Analysis of Flow and Pressure in Pipe Networks

242 Pages·2013·4.04 MB·English

Computer Aided Analysis of Flow and Pressure in
Pipe Networks
By
Mohamed A-Salam Ali
Dublin City University
MEng
2000
Computer Aided Analysis of Flow and Pressure in
Pipe Networks
By
Mohamed A-Salam Ali
This thesis is submitted to Dublin City University as the fulfilment of the
requirement for the award of the degree of
Master of Engineering
Supervisor: Professor M..S.J.Hashmi
School of Mechanical and Manufacturing Engineering
Dublin City University
September, 2000
DECLARATION
I hereby certify that this material, which I now submit for assessment on the
programme of study leading to the award of Master of Engineering is entirely my
own work and has not been taken from the work of others save and to the extent
that such work has been cited and acknowledged within the text of my work.
Signed: — I.D:97970034
Mohamed A-Salam Ali
Date 8th September, 2000
ACKNOWLEDGMENT
I would like to thank to Professor M.SJ.Hashmi for his supervision and
guidance during this research work.
I would also like to thank the School of Mechanical and Manufacturing
Engineering of Dublin City University specially Mr. Brian Corcoran
Liam Domican and Ms. Michelle Considine for their co-operation and
assistance.
Finally, the patience and encouragement of my family deserve a greater
acknowledgement than words can express.
Dedication
To my parents
Computer Aided Analysis of Flow and Pressure in Pipe
Networks
by
Mohamed A-Salam Ali.B.Sc (Eng)
Abstract
Pipeline systems range from the very simple to very large and quite complex ones.
They may be as uncomplicated as a single pipe conveying water from one reservoir to
another or they may be as elaborate as an interconnected set of water distribution
networks for a major metropolitan area. Individual pipelines may contain several
kinds of pumps at one and or at an intermediate point; they may deliver water to or
from storage tanks. A system may consist of a number of sub-networks separated by
differing energy lines or pressure levels that serve neighbourhoods at different
elevation, and some of these may have pressurised tanks so that the pumps need not
operate continuously. In order that these transfer systems will adequately fulfil their
intended functions, they may require the inclusion of pressure reducing or pressure
sustaining valves. These days an understanding of some particular numerical method
and the ability to implement them on a computer, for obtaining solutions for a large
problem is a vitally needed skill. Computations associated with engineering practice
have changed dramatically in the past quarter century from the estimation of a few
key values by using a slide rule to the generation of pages of computer output that are
the result of detailed simulations of system performance. In the steady state analysis
and design of networks, a large system of non-linear equation must be solved. In these
I
work a computer program has been developed which carries out the regular
simulation of steady state pressure and flow in pipe system. The computer program is
written in C Language, to solve the basic pipe system equations using linear method.
Basically the program reads input data defining the parameter for each pipe and each
junction in the network. Connecting node number is the only geometric data in put for
each pipe. From this data, the basic system equations are generated and solved.
II
Contents
Abstract I
Contents III
Chapter One-Introduction and Justification
1.1 Introduction 1
1.2 Computer as tool for analysis and design 1
1.3 Aim of study 3
1.4 Method of approach 3
1.5 Layout of thesis 4
Chapter Two-Review Of Fundamentals
2.1 Introduction 6
2.2 Fluid properties 8
2.2.1 Density 8
2.2.2 Viscosity 11
2.2.3 Pressure 13
2.3 The Fundamental principles 14
2.3.1 Continuity 15
2.3.2 Conservation of energy 18
2.3.3 Momentum principal 25
hi
Chapter Three-Pipe Network Analysis
3.1 Introduction 26
3.2 History of analysis and design pipe network 27
3.2.1 Convergence problem 29
3.3 Basic relation between network element 32
3.4 Algorithm for pipe network 35
3.4.1 Pipe network geometry 35
3.4.2 Basic equation 36
3.4.3 Loop equation 37
3.4.4 Nodes equation 38
3.5 Algorithm for solution node equation 40
3.5.1 Single path adjustment 40
3.5.2 Simulation path adjustment 41
3.6 Algorithms for solving node equation 42
3.6.1 Single node adjustment 42
3.6.2 Simulation node adjustment 42
3.7 Linear method 43
3.8 Gradient method 46
3.9 Steady incompressible flow in pipe network 47
3.9.1 Type of pipe flow problem 49
3.9.2 Method of solution 50
IV
3.9.3 General equation 52
3.10 Reducing complexity of pipe network 52
3.10.1 Series pipe 52
3.10.2 Series pipe flow with pump 54
3.10.3 Parallel pipe 56
3.10.4 Branching system 60
3.11 Equation describing steady flow 60
3.11.1 System of g-equation 60
3.11.2 System of //-equation 64
3.11.3 System of .Dg-equation 66
3.12 Solving networks equation 70
3.12.1 Newton-Raphson method 70
Chapter Four-Simulation
4.1 Introduction 73
4.2 Pipe system characteris 75
4.3 Pipe system Geometry 75
4.3.1 Junction node 76
4.3.2 Fixed grade node 76
4.3.3 Primary loop 76
4.4 Pipe system component 78