dc.contributor.author | Yao, Yue (Edward) | |
dc.date.accessioned | 2017-08-24T12:35:41Z | |
dc.date.available | 2017-08-24T12:35:41Z | |
dc.date.issued | 2017-08-24T12:35:41Z | |
dc.identifier.uri | http://hdl.handle.net/10222/73168 | |
dc.description.abstract | The hydraulic transient phenomenon known as water hammer has a long history [35].
To date, only relatively simple cases have been studied analytically among the numerous
publications. In this research, a formal asymptotic wave attenuation form is found
for each of three water hammer models, i.e., the classic model, an unsteady friction
model, and a generalized Kelvin-Voight model. Explicit dependence of pressure-wave
attenuation on lumped parameters is found and a deeper and more direct understanding
of the water hammer phenomenon is obtained that is unavailable from numerical
methods. Firstly, (Yao et al. [99], Chapter 4), water hammer is treated for variable
valve-closure time using a momentum equation extended to partially developed turbulence
(Hansen et al. [43] 1995, [42] 2011). A closed-form pressure-wave attenuation,
found via multiple-scales asymptotics, is useful over much longer times than previous
ad hoc results (Tijsseling et al. [52] 2000). Numerical validation of analytical results
is obtained using the method of characteristics and convergence verified through a
time and space grid reductions. Experimental validation was not considered. The
contribution includes: (i) understanding of parametric dependence of pressure-wave
attenuation, (ii) capacity to handle time-varying closure cases which is currently unavailable,
and (iii) validity in case of flow reversals given uniform fluid movement.
Secondly, (Yao et al. [98], Chapter 5), an unsteady friction model introduced by
Brunone et al. [16] 1990 to account for turbulence, is considered. An extension of
Chapter 4 is used to find the wave attenuation form. Increased attenuation due to unsteady
friction is reduced to a single time-dependent exponential factor involving the
product of Brunone’s unsteady-friction parameters. The numerical solution, found
as before, was used to verify analytic results. Model parameters chosen to match
experimental results (Bergant et al. [8]) were used here. The analytic form surprisingly
predicts that the steady viscous extension (Hansen et al. [42] 2011), accounting
for partially developed turbulence, provides an equally viable explanation for the increased
pressure-wave attenuation given a weak spatial dependence. Finally, (Yao
et al. [100], Chapter 6), the multiple-scales method (Chapters 4 and 5) is further
extended to water hammer in viscoelastic pipe modelled using a Kelvin-Voight representation.
Pipe plasticity is found to increase the pressure wave attenuation rate via
a third time scale driven by weak strain-rate feedback. A Preissmann weighted fourpoint
box-scheme (Weinerowska-Bords [90] 2006) is used to obtain numerical solutions
to the mathematical model. The analytic work is validated by matching to a numerical
solution matched to experimental data (Mitosec et al. [59]). This contribution
includes: (i) resolution of an outstanding paradox (Weinerowska-Bords [90] 2006) involving
an order of magnitude mismatch between predicted Kelvin-Voight parameters
and those required to match numerical and experimental data, and (ii) introduction
of a novel classification method for the prediction of the scale of lumped-parameters
without access to experimental data. Both (i) and (ii) predict that this work will be
useful in the planning and design phases of experiment and field installations. | en_US |
dc.language.iso | en_US | en_US |
dc.subject | Water hammer | en_US |
dc.subject | Nonlinear | en_US |
dc.subject | Pressure wave attenuation | en_US |
dc.subject | Varying valve closure time | en_US |
dc.subject | Multiple scales analysis | en_US |
dc.subject | Flow reversals | en_US |
dc.subject | Brunone unsteady friction | en_US |
dc.subject | Weak spatial dependence | en_US |
dc.subject | Parameter estimation | en_US |
dc.subject | Polymer | en_US |
dc.subject | Kelvin-Voight | en_US |
dc.subject | Weak strain-rate feedback | en_US |
dc.title | ASYMPTOTIC MULTIPLE-SCALES ANALYSIS OF HYDRAULIC TRANSIENTS IN ELASTIC AND VISCOELASTIC PRESSURIZED CONDUITS | en_US |
dc.date.defence | 2017-06-06 | |
dc.contributor.department | Department of Engineering Mathematics & Internetworking | en_US |
dc.contributor.degree | Doctor of Philosophy | en_US |
dc.contributor.external-examiner | Dr. Tasos Georgiades | en_US |
dc.contributor.graduate-coordinator | Dr. Guy Kember | en_US |
dc.contributor.thesis-reader | Dr. Serguei Iakovlev | en_US |
dc.contributor.thesis-reader | Dr. Mysore Satish | en_US |
dc.contributor.thesis-supervisor | Dr. Guy Kember | en_US |
dc.contributor.thesis-supervisor | Dr. David Hansen | en_US |
dc.contributor.ethics-approval | Not Applicable | en_US |
dc.contributor.manuscripts | Yes | en_US |
dc.contributor.copyright-release | Yes | en_US |