Nestacionarna strujanja u sistemima za transport tečnosti i njihova zaštita
Докторанд
Nikodijević, MilicaМентор
Bogdanović-Jovanović, JasminaЧланови комисије
Mihajlov, DarkoKaradžić, Uroš
Spasić, Živan
Метаподаци
Приказ свих података о дисертацијиСажетак
The subject matter of this dissertation is a general analysis of unsteady flows
in hydraulic transport pipelines with a special focus on small hydropower pipelines
and the determination of dynamic properties of control valves and the stator. The
determined dynamic properties of governors and system behavior are verified
through comparison with the measured results.
The research subject and aims are defined based on the analysis of previous
relevant literature. Mathematical modelling of unsteady fluid flow in pipelines is
conducted. The speed of pressure disturbance during water hammer is determined
and some basic cases of this phenomenon are presented. Based on the review of
available methods that significantly contributed to the study of this phenomenon,
the method of characteristics is deductively selected to solve the relevant
differential equations with boundary and initial conditions, after which different
representations of the friction factor are given. Based on mark...et availability of
different valve types, three of them are selected; calculations and analyses of the
three valves yielded results that were then used to propose the best valve type
water hammer mitigation. Afterward, the basic parameters of water turbines are
described and a classification is provided for the turbines, for which linear and
universal characteristics are then determined according to the main universal
characteristic and the use of universal characteristics to obtain Suter curves is
demonstrated. Water hammer is modelled for systems containing a Pelton and a
Francis turbine and the results for specific small hydropower plants are then
verified against the modelling results. The dissertation also discusses potential
static and hydrodynamic methods of leakage detection in hydraulic transport
systems, with special focus on the method of pressure gradient analysis, which is
then supplemented with unsteady analyses for intentionally created pressure
disturbances in the system.
Based on the developed models for establishing the dynamic properties of
transients, a procedure is proposed for identifying leakage and leakage locations in
a hydraulic system. The obtained results will be used to formulate
recommendations for improved reliability and system protection.