Simulacija promjene opterećenja Francisove hidrauličke turbine

master's thesis

• Title (english): Simulation of Francis hydraulic turbine load variation
• Author: Dario Živković
• Mentor: Željko Tuković (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2016-12-09, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Process Energy Engineering

Abstract

Sve većim udjelom intermitentnih izvora energije povećava se potreba za čestim promjenama radnog režima hidroturbinskih postrojenja. Povećan rad u vanprojektnim radnim točkama, potrebe za variranjem snage i općenito sudjelovanje u pomoćnim uslugama regulacije napona elektroenergetskog sustava uvjeti su s kojima se susreću hidrauličke turbine danas. Sve to uzrokuje dinamička

naprezanja s posljedicama po životni vijek i sigurnost rada postrojenja te veće troškove održavanja.

U ovom radu upotrebljavaju se metode računalne dinamike fluida kako bi se analizirao tok u Francis 99 modelu visokotlačne turbine prilikom prijelaznog režima rada. Za tu svrhu korišten je open source kôd foam-extend. Prikazane su simulacije radne točke najviše iskoristivosti te

simulacije promjene režima rada zakretanjem lopatica statora. Blok strukturirana heksaedarska računska mreža izrađena je ručno za potrebe rada. Metoda pomičnih koordinatnih sustava te metoda rotacije mreže su korištene za simuliranje stacionarne radne točke. Zakretanje regulacijskih lopatica statora iz nazivne radne točke u točku smanjene snage modelirano je rješavanjem jednadžbi gibanja točaka geometrijske mreže kontrolnih volumena. Dva

pristupa zadavanju rubnih uvjeta su testirana, sa zadanom visinom tlaka te zadanim protokom na ulazu. Simulacija sa zadanom visinom tlaka pokazala je zadovoljavaju ́ce rezultate u usporedbi s eksperimentalnim podacima. Modeli turbulencije korišteni u radu su "standardni" k − ε i k − ω SST. Svi parametri u postavkama numeričkih simulacija odgovaraju uvjetima koji su vladali prilikom eksperimentalnih mjerenja objavljenih od strane organizatora Francis 99 konferencije.

Abstract (english)

Due to intermittentcy in electrical grids introduced with ever larger share of renewable power sources, hydroelectric plant operation saw an increase in load variations and overall off-design operation at prolonged time as they are expected to deliver regulating power for the electric grid.

Frequent load variations increased the dynamic loading of turbine parts, particularly runner, affecting the operating life and increasing maintenance-related cost. Detailed studies of transient operating regimes are therefore necessary. In present work, methods of computational fluid mechanics are applied on Francis 99 high head turbine using the open source finite volume code foam-extend. Simulations of both steady state and transient turbine operation were performed. Best efficiency operating point is simulated with both steady-state solver with frozen rotor approach, as well as a transient dynamic mesh solver implementing sliding grid approach. The steady operation simulations were conducted first to test the created mesh and computational modeling choices. Load variation simulations are implemented for load reduction phase, where discharge is regulated by closing of guide vanes from best efficiency point to part load. Two approaches with custom boundary conditions were tested for the domain inlet, one with prescribed head (total pressure) and another with prescribed flow rate (velocity). The simulation with prescribed head showed good agreement with pressure measurements and realistic trend of other integral values.

Two well established turbulence models were used in present work, namely the "standard" k − ε and k − ω SST . All parameters in setup of presented simulations were adjusted to the corresponding conditions during experiments on the Tokke turbine model, results of which were made available by the Francis 99 workshop.

• Keywords: Francis 99; promjena režima rada; računalna dinamika fluida (CFD); pomične mreže kontrolnih volumena; turbostrojevi; hidroturbine
• Keywords (english): Francis 99; load variation simulations; computational fluid dynamics (CFD); mesh motion; turbomachinery; hydroturbines
• Language: english
• URN:NBN: urn:nbn:hr:235:013186
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 18:15:43