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doctoral thesis
Prilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima
Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2012. urn:nbn:hr:235:724763
Korbar, Radoslav
University of Zagreb
Faculty of Mechanical Engineering and Naval Architecture

Institutional repository: Repository of Faculty of Mechanical Engineering and Naval Architecture University of Zagreb

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Korbar, R. (2012). Prilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima (Doctoral thesis). Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture. Retrieved from https://urn.nsk.hr/urn:nbn:hr:235:724763

Korbar, Radoslav. "Prilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima." Doctoral thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2012. https://urn.nsk.hr/urn:nbn:hr:235:724763

Korbar, Radoslav. "Prilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima." Doctoral thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2012. https://urn.nsk.hr/urn:nbn:hr:235:724763

Korbar, R. (2012). 'Prilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima', Doctoral thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, accessed 26 November 2024, https://urn.nsk.hr/urn:nbn:hr:235:724763

Korbar R. Prilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima [Doctoral thesis]. Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture; 2012 [cited 2024 November 26] Available at: https://urn.nsk.hr/urn:nbn:hr:235:724763

R. Korbar, "Prilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima", Doctoral thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, 2012. Available at: https://urn.nsk.hr/urn:nbn:hr:235:724763

Metadata
TitlePrilog modeliranju koeficijenta otpora trenja u nestacionarnom strujanju fluida u cijevima
Title (english)Contribution to modeling of friction coefficient for transient flow in pipes
AuthorRadoslav Korbar
MentorZdravko Virag (mentor)
Committee memberMario Šavar (predsjednik povjerenstva)
Committee memberZdravko Virag (član povjerenstva)
Committee memberVeljko Filipan (član povjerenstva)
GranterUniversity of Zagreb
Faculty of Mechanical Engineering and Naval Architecture
Zagreb
Defense date and country2012-07-18, Croatia
Scientific / art field,
discipline and subdiscipline		TECHNICAL SCIENCES
Mechanical Engineering
Process Energy Engineering
Universal decimal classification
(UDC)		53 - Physics
Abstract
U proračunima nestacionarnog strujanja u cijevi sve češće je potrebno precizno određivanje trenja fluida, što uvjetuje da se uz 1D modele strujanja koriste i točniji kvazi-2D modeli. Za proračun hidrauličkog udara najčešće se koriste 2D modeli Vardy i Hwang (koji je točniji i pouzdaniji) i Pezzinga (koji zahtijeva manje računanja). Ovdje je predložen novi kvazi-2D model koji posjeduje točnost metode Vardy i Hwang i brzinu računanja metode Pezzinga. Ujedno je ponuđena i originalna numerička metoda koja je u osnovi metoda karakteristika, ali ima i neke elemente metode konačnih volumena. \Najprije se daje pregled postojećih modela za proračun hidrauličkog udara od složenijih prema jednostavnijima uz postupno uvođenje pretpostavki. Zatim je sustavno izložena metoda karakteristika za višedimenzijske situacije. Koristeći se karakterističnim jednadžbama, detaljnom analitičkom usporedbom predložene metode i metode Vardy i Hwang pokazuje se da obje metode moraju davati iste rezultate pod uvjetom da se koristi potpuno implicitna shema interpolacije za radijalnu brzinu. \Na kraju su rezultati predložene metode uspoređeni s eksperimentalnim rezultatima za slučaj laminarnog i turbulentnog strujanja, kao i s rezultatima proračuna pomoću metode Vardy i Hwang za te iste strujne situacije. U svim tim usporedbama predložena metoda pokazuje izvrsno poklapanje rezultata.
Abstract (english)
Pipe flow transient calculations demand increasingly precise friction models. Therefore, more accurate quasi-2D flow models are used in addition to simpler 1D models. The most commonly used quasi-2D models for water hammer calculations are those of Vardy and Hwang (more accurate and reliable) and Pezzinga (demands less calculation steps). Here a new quasi-2D model is proposed that combines the accuracy of Vardy and Hwang method and the calculation speed of Pezzinga’s method. Furthermore, an original numerical method is offered. The method essentially relies on the method of characteristics, but it also comprises some finite volume method features. First an overview of existing models is given, that goes from complex models towards simpler ones, and introduces assumptions progressively. Then a detailed description is given of the method of characteristics for multidimensional situations. Applying characteristic equations, a detailed analytical comparison of the proposed and the Vardy and Hwang method shows that both methods must give the same results, provided that a fully implicit interpolation scheme is used for radial velocities. Finally the proposed method results are compared to the experimental ones for situations of laminar and turbulent flow, as well as to the Vardy and Hwang method results for the same flow situations. Results of the proposed method show excellent agreement in all these comparisons.
Keywords
Keywords (english)
Languagecroatian
URN:NBNurn:nbn:hr:235:724763
Study programmeTitle: Mechanical Engineering and Naval Architecture
Study programme type: university
Study level: postgraduate
Academic / professional title: doktor/doktorica znanosti, područje tehničkih znanosti (doktor/doktorica znanosti, područje tehničkih znanosti)
Type of resourceText
File originBorn digital
Access conditionsOpen access
Terms of useLicence In copyright icon
Created on2020-05-10 21:28:22