The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform

Silvia Meniconi - One of the best experts on this subject based on the ideXlab platform.

  • Transient Effects of Self-adjustment of Pressure Reducing Valves☆
    Procedia Engineering, 2015
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Elisa Mazzetti, Daniele B. Laucelli, Giovanni Borta
    Abstract:

    Abstract Pressure control strategy through Pressure Reducing Valves (PRV) has been deeply investigated as management strategy, aimed at water leakages reduction avoiding very expensive pipe replacement programs. On the contrary, few experimental data are available in literature, with regard to PRV transient behavior in terms of its response to incoming pressure waves, as well as the time required for achieving the pressure set point. In this paper, the results of some experimental tests are presented. The PRV is installed in a single high density polyethylene pipe and transients are generated by operating the downstream end Valve. Two types of tests are considered: a partial Valve closure and opening simulating a water demand decrease and increase, respectively. The analysis of the experimental pressure traces points out the valuable effects of the PRV on transient characteristics with respect to the case of a partially closed in-Line Valve with a constant opening degree.

  • Energy dissipation and pressure decay during transients in viscoelastic pipes with an in-Line Valve
    Journal of Fluids and Structures, 2014
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract In this paper, the effect of a partially closed in-Line Valve, viscoelasticity, and unsteady friction on the transient behavior of a pressurized pipe is examined. Such an analysis is executed by considering global energy quantities evaluated by means of a one-dimensional numerical model calibrated on the basis of a huge amount of laboratory tests. In the numerical experiments, the effect of the initial conditions and in-Line Valve characteristics has been analyzed by considering different values of the initial Reynolds number, N 0 , in-Line Valve head loss coefficient, χ , and location, δ . By introducing dimensionless quantities, exponential laws are shown to interpolate the time-history of maxima of both pressure and global energy quantities reliably with the related coefficients being a function of N 0 , χ , and δ . Thus, the links between the decay of pressure peaks at single sections and the dissipation of the global kinetic and internal energy are established. Moreover, it is shown that a given decay of pressure peaks may derive from very different transients. This result has crucial implications to inverse transient analysis based on the evaluation of the pressure decay at a given section with particular attention to the uniqueness of the solution.

  • Numerical and experimental investigation of leaks in viscoelastic pressurized pipe flow
    Drinking Water Engineering and Science, 2013
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract. This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-Line Valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). Tests are based on laboratory experiments carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and the use of different numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the examined transients.

  • Effectiveness Assessment of Pipe Systems by Means of Transient Test-based Techniques
    Procedia Environmental Sciences, 2013
    Co-Authors: Bruno Brunone, Silvia Meniconi, Marco Ferrante, Christian Massari
    Abstract:

    In this paper, the reliability of transient test-based techniques for detecting pipe system anomalies is shown by means of numerical and experimental tests – both in laboratory and real pipe systems – with particular regard to the case of a partially closed in-Line Valve. With regard to the analysis of pressure signals, attention is focused on the time domain approach. Moreover, the optimal modality of transient test execution is discussed. References concerning the diagnosis of other anomalies (e.g., leaks, partial blockages, and illegal connections) by means of transient tests are also included for the interested reader.

  • Numerical and experimental investigation of leaks in viscoelastic pressurized pipes
    2012
    Co-Authors: Silvia Meniconi, B. Brunone, M. Ferrante, C. Massari
    Abstract:

    Abstract. This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-Line Valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). The analysis is based on laboratory tests carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and numerical experiments by means of different 1-D numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the transients, also in the case of a damaged pipes.

Christian Massari - One of the best experts on this subject based on the ideXlab platform.

  • Energy dissipation and pressure decay during transients in viscoelastic pipes with an in-Line Valve
    Journal of Fluids and Structures, 2014
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract In this paper, the effect of a partially closed in-Line Valve, viscoelasticity, and unsteady friction on the transient behavior of a pressurized pipe is examined. Such an analysis is executed by considering global energy quantities evaluated by means of a one-dimensional numerical model calibrated on the basis of a huge amount of laboratory tests. In the numerical experiments, the effect of the initial conditions and in-Line Valve characteristics has been analyzed by considering different values of the initial Reynolds number, N 0 , in-Line Valve head loss coefficient, χ , and location, δ . By introducing dimensionless quantities, exponential laws are shown to interpolate the time-history of maxima of both pressure and global energy quantities reliably with the related coefficients being a function of N 0 , χ , and δ . Thus, the links between the decay of pressure peaks at single sections and the dissipation of the global kinetic and internal energy are established. Moreover, it is shown that a given decay of pressure peaks may derive from very different transients. This result has crucial implications to inverse transient analysis based on the evaluation of the pressure decay at a given section with particular attention to the uniqueness of the solution.

  • Numerical and experimental investigation of leaks in viscoelastic pressurized pipe flow
    Drinking Water Engineering and Science, 2013
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract. This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-Line Valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). Tests are based on laboratory experiments carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and the use of different numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the examined transients.

  • Effectiveness Assessment of Pipe Systems by Means of Transient Test-based Techniques
    Procedia Environmental Sciences, 2013
    Co-Authors: Bruno Brunone, Silvia Meniconi, Marco Ferrante, Christian Massari
    Abstract:

    In this paper, the reliability of transient test-based techniques for detecting pipe system anomalies is shown by means of numerical and experimental tests – both in laboratory and real pipe systems – with particular regard to the case of a partially closed in-Line Valve. With regard to the analysis of pressure signals, attention is focused on the time domain approach. Moreover, the optimal modality of transient test execution is discussed. References concerning the diagnosis of other anomalies (e.g., leaks, partial blockages, and illegal connections) by means of transient tests are also included for the interested reader.

  • Transient hydrodynamics of in-Line Valves in viscoelastic pressurized pipes: long-period analysis
    Experiments in Fluids, 2012
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    The literature contains few reports devoted to the analysis of the effects of a partially closed in-Line Valve on the characteristics of transients in viscoelastic pressurized pipes. In this paper a contribution to the analysis of the long-period behavior of pressure is offered from both the experimental and numerical modeling point of view. In the first part, laboratory tests and the related results—noticeably extensive with respect to the existing literature—are examined. More precisely, the dependance of the damping of the dimensionless pressure maximum values on the initial conditions and in-Line Valve local head loss coefficient is shown. In the second part, a 1-D numerical model is developed by determining its parameters within a physically based procedure. Model parameters are obtained by considering transients in a constant-diameter pipe (single pipe) and then exported to the case of pipes with a partially closed in-Line Valve (in-Line Valve pipe). Moreover, particular attention is devoted to the modalities of specifying boundary conditions. In particular, the quasi-steady-state approach is followed for determining the transient local head loss due to the partially closed in-Line Valve and the actual supply conditions and characteristics of the maneuver are taken into account. Finally, the effect of unsteady friction and viscoelasticity is examined in both single and in-Line Valve pipes.

  • Potential of Transient Tests to Diagnose Real Supply Pipe Systems: What Can Be Done with a Single Extemporary Test
    Journal of Water Resources Planning and Management, 2011
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    In this paper, the reliability of a transient test-based technique as a powerful tool in the management of real supply pipe systems is shown. The pressure signal acquired during the first phase of the single completed test has been analyzed on the basis of extensive research activity performed in the previous years in the field of transient test-based techniques and refined on the basis of numerical and laboratory tests. Specifically, the wavelet transform, which allows the automatic detection of singularities in noisy pressure signals, and a Lagrangian model, which evaluates the causes of discontinuities, are efficiently coupled for analyzing the pressure signal acquired in the described pipe system. As a result, the topology of such a system has been checked, and its functioning conditions have been determined. Moreover, the unwanted status of an in-Line Valve—certified by the manager as fully open but actually partially closed—has been pointed out.

Marco Ferrante - One of the best experts on this subject based on the ideXlab platform.

  • Transient Effects of Self-adjustment of Pressure Reducing Valves☆
    Procedia Engineering, 2015
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Elisa Mazzetti, Daniele B. Laucelli, Giovanni Borta
    Abstract:

    Abstract Pressure control strategy through Pressure Reducing Valves (PRV) has been deeply investigated as management strategy, aimed at water leakages reduction avoiding very expensive pipe replacement programs. On the contrary, few experimental data are available in literature, with regard to PRV transient behavior in terms of its response to incoming pressure waves, as well as the time required for achieving the pressure set point. In this paper, the results of some experimental tests are presented. The PRV is installed in a single high density polyethylene pipe and transients are generated by operating the downstream end Valve. Two types of tests are considered: a partial Valve closure and opening simulating a water demand decrease and increase, respectively. The analysis of the experimental pressure traces points out the valuable effects of the PRV on transient characteristics with respect to the case of a partially closed in-Line Valve with a constant opening degree.

  • Energy dissipation and pressure decay during transients in viscoelastic pipes with an in-Line Valve
    Journal of Fluids and Structures, 2014
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract In this paper, the effect of a partially closed in-Line Valve, viscoelasticity, and unsteady friction on the transient behavior of a pressurized pipe is examined. Such an analysis is executed by considering global energy quantities evaluated by means of a one-dimensional numerical model calibrated on the basis of a huge amount of laboratory tests. In the numerical experiments, the effect of the initial conditions and in-Line Valve characteristics has been analyzed by considering different values of the initial Reynolds number, N 0 , in-Line Valve head loss coefficient, χ , and location, δ . By introducing dimensionless quantities, exponential laws are shown to interpolate the time-history of maxima of both pressure and global energy quantities reliably with the related coefficients being a function of N 0 , χ , and δ . Thus, the links between the decay of pressure peaks at single sections and the dissipation of the global kinetic and internal energy are established. Moreover, it is shown that a given decay of pressure peaks may derive from very different transients. This result has crucial implications to inverse transient analysis based on the evaluation of the pressure decay at a given section with particular attention to the uniqueness of the solution.

  • Numerical and experimental investigation of leaks in viscoelastic pressurized pipe flow
    Drinking Water Engineering and Science, 2013
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract. This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-Line Valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). Tests are based on laboratory experiments carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and the use of different numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the examined transients.

  • Effectiveness Assessment of Pipe Systems by Means of Transient Test-based Techniques
    Procedia Environmental Sciences, 2013
    Co-Authors: Bruno Brunone, Silvia Meniconi, Marco Ferrante, Christian Massari
    Abstract:

    In this paper, the reliability of transient test-based techniques for detecting pipe system anomalies is shown by means of numerical and experimental tests – both in laboratory and real pipe systems – with particular regard to the case of a partially closed in-Line Valve. With regard to the analysis of pressure signals, attention is focused on the time domain approach. Moreover, the optimal modality of transient test execution is discussed. References concerning the diagnosis of other anomalies (e.g., leaks, partial blockages, and illegal connections) by means of transient tests are also included for the interested reader.

  • water hammer pressure waves interaction at cross section changes in series in viscoelastic pipes
    Journal of Fluids and Structures, 2012
    Co-Authors: Silvia Meniconi, Uno Unone, Marco Ferrante
    Abstract:

    Abstract In view of scarcity of both experimental data and numerical models concerning transient behavior of cross-section area changes in pressurized liquid flow, the paper presents laboratory data and numerical simulation of the interaction of a surge wave with a partial blockage by a Valve, a single pipe contraction or expansion and a series of pipe contraction/expansion in close proximity. With regard to a single change of cross-section area, laboratory data point out the completely different behavior with respect to one of the partially closed in-Line Valves with the same area ratio. In fact, for the former the pressure wave interaction is not regulated by the steady-state local head loss. With regard to partial blockages, transient tests have shown that the smaller the length, the more intense the overlapping of pressure waves due to the expansion and contraction in series. Numerically, the need for taking into account both the viscoelasticity and unsteady friction is demonstrated, since the classical water-hammer theory does not simulate the relevant damping of pressure peaks and gives rise to a time shifting between numerical and laboratory data. The transient behavior of a single local head loss has been checked by considering tests carried out in a system with a partially closed in-Line Valve. As a result, the reliability of the quasi steady-state approach for local head loss simulation has been demonstrated in viscoelastic pipes. The model parameters obtained on the basis of transients carried out in single pipe systems have then been used to simulate transients in the more complex pipe systems. These numerical experiments show the great importance of the length of the small-bore pipe with respect to one of the large-bore pipes. Precisely, until a gradually flow establishes in the small-bore pipe, the smaller such a length, the better the quality of the numerical simulation.

Bruno Brunone - One of the best experts on this subject based on the ideXlab platform.

  • Transient Effects of Self-adjustment of Pressure Reducing Valves☆
    Procedia Engineering, 2015
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Elisa Mazzetti, Daniele B. Laucelli, Giovanni Borta
    Abstract:

    Abstract Pressure control strategy through Pressure Reducing Valves (PRV) has been deeply investigated as management strategy, aimed at water leakages reduction avoiding very expensive pipe replacement programs. On the contrary, few experimental data are available in literature, with regard to PRV transient behavior in terms of its response to incoming pressure waves, as well as the time required for achieving the pressure set point. In this paper, the results of some experimental tests are presented. The PRV is installed in a single high density polyethylene pipe and transients are generated by operating the downstream end Valve. Two types of tests are considered: a partial Valve closure and opening simulating a water demand decrease and increase, respectively. The analysis of the experimental pressure traces points out the valuable effects of the PRV on transient characteristics with respect to the case of a partially closed in-Line Valve with a constant opening degree.

  • Energy dissipation and pressure decay during transients in viscoelastic pipes with an in-Line Valve
    Journal of Fluids and Structures, 2014
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract In this paper, the effect of a partially closed in-Line Valve, viscoelasticity, and unsteady friction on the transient behavior of a pressurized pipe is examined. Such an analysis is executed by considering global energy quantities evaluated by means of a one-dimensional numerical model calibrated on the basis of a huge amount of laboratory tests. In the numerical experiments, the effect of the initial conditions and in-Line Valve characteristics has been analyzed by considering different values of the initial Reynolds number, N 0 , in-Line Valve head loss coefficient, χ , and location, δ . By introducing dimensionless quantities, exponential laws are shown to interpolate the time-history of maxima of both pressure and global energy quantities reliably with the related coefficients being a function of N 0 , χ , and δ . Thus, the links between the decay of pressure peaks at single sections and the dissipation of the global kinetic and internal energy are established. Moreover, it is shown that a given decay of pressure peaks may derive from very different transients. This result has crucial implications to inverse transient analysis based on the evaluation of the pressure decay at a given section with particular attention to the uniqueness of the solution.

  • Numerical and experimental investigation of leaks in viscoelastic pressurized pipe flow
    Drinking Water Engineering and Science, 2013
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    Abstract. This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-Line Valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). Tests are based on laboratory experiments carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and the use of different numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the examined transients.

  • Effectiveness Assessment of Pipe Systems by Means of Transient Test-based Techniques
    Procedia Environmental Sciences, 2013
    Co-Authors: Bruno Brunone, Silvia Meniconi, Marco Ferrante, Christian Massari
    Abstract:

    In this paper, the reliability of transient test-based techniques for detecting pipe system anomalies is shown by means of numerical and experimental tests – both in laboratory and real pipe systems – with particular regard to the case of a partially closed in-Line Valve. With regard to the analysis of pressure signals, attention is focused on the time domain approach. Moreover, the optimal modality of transient test execution is discussed. References concerning the diagnosis of other anomalies (e.g., leaks, partial blockages, and illegal connections) by means of transient tests are also included for the interested reader.

  • Transient hydrodynamics of in-Line Valves in viscoelastic pressurized pipes: long-period analysis
    Experiments in Fluids, 2012
    Co-Authors: Silvia Meniconi, Marco Ferrante, Bruno Brunone, Christian Massari
    Abstract:

    The literature contains few reports devoted to the analysis of the effects of a partially closed in-Line Valve on the characteristics of transients in viscoelastic pressurized pipes. In this paper a contribution to the analysis of the long-period behavior of pressure is offered from both the experimental and numerical modeling point of view. In the first part, laboratory tests and the related results—noticeably extensive with respect to the existing literature—are examined. More precisely, the dependance of the damping of the dimensionless pressure maximum values on the initial conditions and in-Line Valve local head loss coefficient is shown. In the second part, a 1-D numerical model is developed by determining its parameters within a physically based procedure. Model parameters are obtained by considering transients in a constant-diameter pipe (single pipe) and then exported to the case of pipes with a partially closed in-Line Valve (in-Line Valve pipe). Moreover, particular attention is devoted to the modalities of specifying boundary conditions. In particular, the quasi-steady-state approach is followed for determining the transient local head loss due to the partially closed in-Line Valve and the actual supply conditions and characteristics of the maneuver are taken into account. Finally, the effect of unsteady friction and viscoelasticity is examined in both single and in-Line Valve pipes.

Chul-hwa Song - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Key Parameters on the APR1400 In-Containment Refueling Water Storage Tank Hydrodynamic Loads
    Journal of Nuclear Science and Technology, 2003
    Co-Authors: Choon-kyung Park, Chul-hwa Song
    Abstract:

    A series of sparger tests have been conducted to investigate the performance of a steam sparger, which will be used in a Korean Advanced Power Reactor, APR1400. The tests have been conducted at the Blowdown and Condensation Loop in the Korea Atomic Energy Research Institute using a prototypic steam sparger. The major test parameters include amount of air mass and air temperature in the discharge Line, Valve opening time, steam mass flow rate, and water temperature and level in the In-Containment Refueling Water Storage Tank. The hydrodynamic loads induced by the air clearing phenomenon during typical operating conditions seem to be dependent on the Valve opening time, steam mass flow rate, submergence of a sparger, and distance between the sparger and the structure. The effect of the amount of air mass in the discharge Line and the water temperature to the peak load seems to be negligible for a given range of parameters. The hydrodynamic load induced by the prototypic steam sparger was less than those exp...