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Inhaltsverzeichnis

Frontmatter

1. Simple waterhammer theory

Abstract
The hydraulic analysis of flow in networks is usually based upon the consideration of steady state conditions. This is due to historic reasons; the analysis of unsteady state is an order of magnitude more difficult than that of steady state and was only possible at all if grossly simplifying assumptions were made. Until the relatively recent development of computers the only methods available were graphical in type and these could only be applied to simple networks in which the hydraulic controls were of an elementary nature and in which the number of pipes was small.
J. A. Fox

2. Analytic and graphical methods

Abstract
It is necessary to discuss the work that has been done in the past on the analysis of transients generated by slow movements of hydraulic controls. As this chapter is still concerned with providing a background to the more modern techniques of analysis that will be presented in later chapters only an outline will be provided.
J. A. Fox

3. Boundary conditions for use with graphical methods

Abstract
In chapter 2 the fundamental techniques of graphical analysis have been demonstrated but, throughout, the downstream boundary condition was always assumed to be that of a closing valve. In this chapter, methods of dealing with other boundary conditions are described.
J. A. Fox

4. The method of characteristics

Abstract
The Schnyder-Bergeron technique has, until recently, been considered the best method of solving transient problems. It is very limited and subject to error, however. The work involved in analysing networks containing a significant number of pipes, say more than eight or nine, is unacceptable in any engineering circumstance. However, there are more complex reasons for considering graphical methods to be inadequate.
J. A. Fox

5. Variable parameters in unsteady flow

Abstract
The variation of wavespeed has been mentioned in earlier chapters. Wavespeed is dependent upon the effective bulk modulus of the fluid and this has already been shown to be dependent upon the distensibility of the pipe, i.e.
J. A. Fox

6. Boundary conditions: pumps

Abstract
The writing of a computer program to perform unsteady network analysis depends upon an accurate description of wave transmission (described in chapter 5) which is relatively simple to do, but the problem of describing the boundary conditions that either generate the unsteadiness or reflect (totally or partially) pressure transients already generated is more difficult.
J. A. Fox

7. Other boundary conditions

Abstract
As stated earlier it is vitally necessary to have a subroutine/procedure which is capable of describing an ‘n way’ junction if a program is to have any generality.
J. A. Fox

8. Unsteady flow in gas networks

Abstract
The methods presented for analysing unsteady flow in pipe networks transporting liquids need modification before they can be applied to highly compressible fluids such as gases.
J. A. Fox

9. Impedance methods of pipeline analysis

Abstract
It is possible for resonance to occur in pipe networks. Organ pipes and other musical wind instruments operate by generating such a resonance. Small pressure or flow fluctuations applied at one end of a pipeline can superimpose upon one another if their frequency matches a simple multiple of the pipeline’ s period leading to the development of a standing wave of considerable magnitude. This phenomenon has caused some major catastrophes: pipelines have ruptured when the forcing vibration has been of trivial magnitude. One of the circumstances which will generate small fluctuations of pressure or flow is the oscillating valve. A very common example of this is the vibrating ball valve in a domestic water supply. As the level in the cistern rises it raises the ball which progressively closes the valve. If the valve is very nearly closed, a small further closing movement shuts off all flow causing a pressure wave to travel down the supply pipe. The pressure rise tends to force the valve off its seat and to let flow recommence so initiating a negative pressure wave which starts off down the pipe following the initial positive wave.
J. A. Fox

10. Unsteady flow in open channels

Abstract
Flow in open channels is normally considered in steady state conditions only. The methods of analysis of unsteady flow conditions in pipe networks can be applied to open channel networks with only trivial modification however.
J. A. Fox

11. Global programming

Abstract
A global program is one which provides the facility of being able to describe the topology of any pipe network by the use of numbers, which are read in as data. Additionally the presence, or absence, of any particular hydraulic control, such as a pump, turbine, reservoir, air vessel at any location must also be capable of specification by the use of numbers.
J. A. Fox

Backmatter

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