Proračun opterećenja vjetra na plutajući pučinski objekt

master's thesis

• Title (english): Wind load computations of a offshore floating object
• Author: Ivica Jovan
• Mentor: Hrvoje Jasak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2018-01-24, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Vrlo visoke i kompleksne građevine moraju biti u stanju izdržati vremenske uvjete kojima su izložene, barem u mjeri u kojoj su katastrofalna oštećenja svedena na prihvatljivu granicu.
Jedne od takvih građevina su naftne platforme koje su zbog smještenosti na otvorenom moru izložene utjecaju jakih vjetrova. Točna procjena i predviđanje opterećenje vjetra vrlo su važni u smanjenju štetnih učinaka. Dosadašnje metode korištene u proučavanju strujanja vjetra oko objekata su mjerenje na postojećim objektima te mjerenja u zračnim tunelima, koja su zbog kompleksnosti vrlo skupa. Napretkom računalne tehnologije neizostavni segmet analize kompleksnih strujanja fluida je Računalna Dinamika Fluida (RDF) (eng. "CFD") koja postaje alternativa dosadašnjim metodama.
U sklopu ovog rada, softver otvorenog koda foam-extend upotrebljen je za simulacije nestlačivog strujanja oko dva različita modela (Test D i Test J) naftne platforme konstruirane sa uparenim stupovima (eng. Paired-Column Semi submersible platform). 3D CAD model naftne platforme dobiven je u sklopu projekta Usporedna istraživanja o utjecaju vjetra.
Numeričke simulacije provedene su za četiri slučaja, pri čemu su za svaki od modela korištena dva različita pristupa modeliranja turbulencije: vremenski osrednjene Navier - Stokesove jednadžbe (eng. "Reynolds Averaged Navier - Stokes", skraćeno RANS) i simulacije velikih vrtloga (eng. "Large Eddy Simulations", skraćeno LES).
Rezultati numeričkih simulacija prikazani su u obliku polja značajnih fizikalnih veličina.
Izvršena je usporedba atmosferskog graničnog sloja modeliranog u simulacijama sa atmosferskim graničnim slojem dobivenim u zračnom tunelu. Isto tako uspoređene su vrijednosti normalizirane sile i normaliziranog momenta sa vrijednostima dobivenim u zračnom tunelu.

Abstract (english)

Very high and complex structures need to be able to withstand the external loads imposed by nature, at least to the extent that the disastrous damage of natural forces is reduced to acceptable limits. One of such structures are oil platforms that are exposed to the influence of strong winds due to their location on the open sea. Accurate assessment and prediction of wind loads are very important for reducing adverse effects.
The current methods used for studying wind effects around objects are measurements on existing objects and measurements in wind tunnels. However they are complex and expensive. Due to the rapid development of computer technology, the unavoidable segment of complex fluid flow analysis is Computational Fluid Dynamics (CFD) which is becoming an alternative method.
In this thesis, the open source CFD package foam-extend is used to simulate incompressible flow around two different Paired-Column Semi submersible platform models (Test D and Test J). The 3D CAD models were obtained from SNAME OC-8 Comparative Wind Load Study. Numerical simulations are performed for four different cases. Each of the models are simulated with two different approaches of turbulence modelling, RANS and LES.
The results of numerical simulations are presented as images of the flow field for different variables. A comparison of the atmospheric boundary layer obtained from simulations and in the wind tunnel is shown. The values of force coefficient and moment coefficients are also compared with the values obtained in the wind tunnel.

• Keywords: Računalna dinamika fluida; foam-extend; utjecaj vjetra na građevine; naftna platforma
• Keywords (english): CFD; foam-extend; influence of wind; Paired-Column Semi submersible platform
• Language: english
• URN:NBN: urn:nbn:hr:235:496991
• 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 21:20:55