Civil Engineering and Environmental Systems, Jan 2, 2016
ABSTRACT Models of water pipeline systems should take into account the distribution in space and ... more ABSTRACT Models of water pipeline systems should take into account the distribution in space and time of user demands and leakage. In the usual approach such a distribution is simplified lumping the system outflows at a reduced number of nodes. To investigate the effects of such a simplification, in this paper we explore by numerical models, both in the time and in the frequency domain, the uncertainty introduced by the random variation in leak size, location and number. The novelty is also in considering the number of leaks as a parameter. In the time domain, results show that the damping increases with the number of leaks. The spreading of the simulated pressure signals increases with time whereas it decreases with the number of leaks. In the frequency domain, the local minima and maxima values of the impedance are affected by the number of leaks for a given total outflow from the system.
In recent decades the hydraulics of leaks, i.e. the definition of the relationships linking the h... more In recent decades the hydraulics of leaks, i.e. the definition of the relationships linking the hydraulic quantities in pipes with leaks, has received increasing attention. On the one hand, the definition of the relationship between the leak outflow and the relevant parameters – e.g. the leak area and shape, the pressure inside the pipe and outside the leak, and the pipe material – is crucial for pressure control and inverse analysis techniques. On the other hand, if the effect of the leakage on the governing equations is not taken into account, i.e. the loss of the flow axial momentum is not considered, significant errors can be introduced in the simulation of water distribution systems. In this paper, the governing equations for a pipe with a leak are derived. The basic equations, obtained within different approaches, are presented in a consistent formulation and then compared with the results of some experimental tests. The leak jet angle and other major features of the results are analysed. The estimated values of the parameters can be used in the water distribution network models when pipes with a diffuse leakage are considered.
Pressure waves, while traveling along pressurized pipes, collect precious information about possi... more Pressure waves, while traveling along pressurized pipes, collect precious information about possible faults (e.g., leaks and partial blockages). In fact, the characteristics of the pressure wave reflected by the fault are strongly related to it. To encourage the use of the transient test-based technologies (TTBTs) for partial blockage (PB) detection in pressurized pipe systems, it can be of interest to critically analyze the available experimental results and to point out the aspects that need to be investigated in more detail, since no review has been executed so far. Such a deficiency has two negative consequences. The first one is that TTBTs are still relegated to limbo by technicians. The second one is that not enough material is available for refining tools to extract all the information contained in the acquired pressure signals and then to pursue an effective PB detection. As main results of the executed analysis, the following issues can be counted: (i) the lack of tests car...
Civil Engineering and Environmental Systems, Jan 2, 2016
ABSTRACT Models of water pipeline systems should take into account the distribution in space and ... more ABSTRACT Models of water pipeline systems should take into account the distribution in space and time of user demands and leakage. In the usual approach such a distribution is simplified lumping the system outflows at a reduced number of nodes. To investigate the effects of such a simplification, in this paper we explore by numerical models, both in the time and in the frequency domain, the uncertainty introduced by the random variation in leak size, location and number. The novelty is also in considering the number of leaks as a parameter. In the time domain, results show that the damping increases with the number of leaks. The spreading of the simulated pressure signals increases with time whereas it decreases with the number of leaks. In the frequency domain, the local minima and maxima values of the impedance are affected by the number of leaks for a given total outflow from the system.
In recent decades the hydraulics of leaks, i.e. the definition of the relationships linking the h... more In recent decades the hydraulics of leaks, i.e. the definition of the relationships linking the hydraulic quantities in pipes with leaks, has received increasing attention. On the one hand, the definition of the relationship between the leak outflow and the relevant parameters – e.g. the leak area and shape, the pressure inside the pipe and outside the leak, and the pipe material – is crucial for pressure control and inverse analysis techniques. On the other hand, if the effect of the leakage on the governing equations is not taken into account, i.e. the loss of the flow axial momentum is not considered, significant errors can be introduced in the simulation of water distribution systems. In this paper, the governing equations for a pipe with a leak are derived. The basic equations, obtained within different approaches, are presented in a consistent formulation and then compared with the results of some experimental tests. The leak jet angle and other major features of the results are analysed. The estimated values of the parameters can be used in the water distribution network models when pipes with a diffuse leakage are considered.
Pressure waves, while traveling along pressurized pipes, collect precious information about possi... more Pressure waves, while traveling along pressurized pipes, collect precious information about possible faults (e.g., leaks and partial blockages). In fact, the characteristics of the pressure wave reflected by the fault are strongly related to it. To encourage the use of the transient test-based technologies (TTBTs) for partial blockage (PB) detection in pressurized pipe systems, it can be of interest to critically analyze the available experimental results and to point out the aspects that need to be investigated in more detail, since no review has been executed so far. Such a deficiency has two negative consequences. The first one is that TTBTs are still relegated to limbo by technicians. The second one is that not enough material is available for refining tools to extract all the information contained in the acquired pressure signals and then to pursue an effective PB detection. As main results of the executed analysis, the following issues can be counted: (i) the lack of tests car...
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Papers by Bruno Brunone