Numerička karakterizacija brodskog propelera

master's thesis

• Title (english): Numerical characterisation of a ship propeller
• Author: Borna Šeb
• Mentor: Hrvoje Jasak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2017-03-31, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Marine Mechanical Engineering

Abstract

Napretkom računalne tehnologije računalne metode u dinamici fluida (RDF) postale su dostupne za korištenje u inženjerskoj praksi pa tako i za odred̄ivanje hidrodinamičkih značajki brodskog vijka. U ovom radu ispitivane su tri metode simulacije eksperimenta slobodne vožnje brodskog vijka:
• simulacija jedne lopatice brodskog vijka metodom višestrukih referentnih koordinatnih sustava (eng. "Multiple Frames of Reference", skraćeno MRF),
• simulacija cijelog brodskog vijka u MRF pristupu,
• tranzijentna simulacija brodskog vijka.
U svrhu evaluacije pojedine metode, rezultati svake od simulacija su uspored̄eni s eksperimentalnim podacima kako bi im se odredila točnost te su med̄usobno uspored̄ene obzirom na potrebne računalne resurse. Pokus slobodne vožnje služi kako bi se izračunale radne karakteristike potrebne prilikom projektiranja brodskog vijka. Med̄utim, izvedba pokusa ne uzima u obzir interakciju izmed̄u strujanja brodskog vijka i krme broda koja je bitna za odred̄ivanje propulzijskih značajki broda. U tu svrhu izvodi se eksperiment vlastitog pogona kod kojeg je model brodskog vijka ugrad̄en na model krme. RDF simulacija pokusa vlastitog pogona iznimno je skupa jer zahtijeva visoku prostornu i vremensku rezoluciju. Korištenje grublje prostorne i vremenske rezolucije moguće je ako se brodski vijak u takvim simulacijama modelira teorijom idealnog propelera. Takvo pojednostavljenje može u velikoj mjeri smanjiti računalne troškove. U ovom radu provedena je evaluacija modela idealnog vijka koja je izvedena usporedbom rezultirajućeg polja strujanja s poljem strujanja dobivenim iz simulacije oko geometrije brodskog vijka.

Abstract (english)

Due to the rapid development of computer technology Computational Fluid Dynamics (CFD) have become a viable tool for hydrodinamic analysis of ship propellers. The open water test for the propeller, traditionally performed to obtain the characteristics used in design, is often simulated with the CFD methods. In this thesis three different CFD methods for simulating the open water test are evaluated based on their accuracy and computational time. They are respectively:
• multiple frames of reference (MRF) for a single blade passage with periodic boundary conditions,
• MRF for complete propeller geometry,
• transient simulation with a rotating mesh and complete propeller geometry.

For some naval applications the interaction between the propeller and ship flows has to be resolved correctly. Solving the flow around the exact propeller geometry in such simulations can be extremely demanding in terms of CPU requirements, which sometimes makes them unfeasible. As an alternative, it is preferred to define an actuator disc region at the location of the propeller at which the momentum transferred from the propeller to the fluid is modelled. In this thesis the open water characteristics from the resolved propeller geometry are used for modelling the propeller influence on the flow with the actuator disc approach. The performance of the actuator disc is afterwards evaluated against the CFD results for the actual propeller geometry.

• Keywords: RDF; OpenFoam; Eksperiment slobodne vožnje brodskog vijka; MRF; Model idealnog propelera
• Keywords (english): CFD; OpenFOAM; Open water test; MRF; Actuator disc
• Language: english
• URN:NBN: urn:nbn:hr:235:498992
• 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 19:27:41