Transient hydrodynamics of in-line valves in viscoelastic pressurized pipes: long-period analysis

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.

On transient liquid flow

“…The details of the initial and boundary conditions and the procedure used to match the numerical and experimental results are presented in the ''Appendix 1''. More information of the experimental setup can be found in [14].…”

Numerical and experimental investigation of leaks in viscoelastic pressurized pipes

“…It can be noted the larger damping occurring in the damaged pipe with respect to the single pipe, as well as that the larger the leak, the larger such a damping (Collins et al, 2012;Colombo et al, 2009). According to literature (Covas et al, 2004(Covas et al, , 2005Franke and Seyler, 1983;Ghilardi and Paoletti, 1986;Meniconi et al, 2012a, b;Soares et al, 2008), the complete 1-D numerical model to simulate transients in pressurized viscoelastic pipes is based on the continuity equation:…”

“…with s = axial co-ordinate, J = total friction term, and ε r = retarded strain. More details on the model and the calibration procedure are reported in Meniconi et al (2011Meniconi et al ( , 2012a. It is worthy of noting that J is regarded as the sum of two components.…”

“…1c) pipes. This result has motivated the intense research activity in the field of unsteady friction (Adamkowski and Lewandowski, 2006;Bergant et al, 2001;Brunone et al, 1991Brunone et al, , 1995Brunone and Berni, 2010;Ghidaoui et al, 2005;Pezzinga, 2000Pezzinga, , 2009Storli and Nielsen, 2011;Zielke, 1968) and viscoelasticity (Covas et al, 2004(Covas et al, , 2005Ferrante et al, 2011;Franke and Seyler, 1983;Ghilardi and Paoletti, 1986;Meniconi et al, 2012a, b;Soares et al, 2008) modelling during transients in pressurized pipes in the last two decades. In fact the damping and rounding of pressure peaks in a single pipe are ascribed to the effect of unsteady friction in elastic pipes and to both unsteady friction and viscoelasticity in plastic ones.…”

Local and Integral Energy-Based Evaluation for the Unsteady Friction Relevance in Transient Pipe Flows

“…The instant of time at which Q P ¼ 0 gives the value of T. In such a way, the actual inertia of the pumps has been taken into account properly. The detailed information has been given in Meniconi et al (2012). According to the ITA results, in the current paper, when the 1D and 2D models were used for the numerical simulations, an approximate linear discharge curve (0 ∼ T) has been applied.…”