Numerička analiza vlastitog pogona broda za prijevoz rasutog tereta vjetrom potpomognutom propulzijom

master's thesis

• Title (english): Numerical analysis of self-propulsion of a bulk carrier with wind-assisted propulsion
• Author: Ivan Tomljenović
• Mentor: Nikola Vladimir (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2023-12-06, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Marine Mechanical Engineering

Abstract

U ovom diplomskom radu provedeno je numeričko istraživanje utjecaja vjetrom potpomognute propulzije broda za rasuti teret na njegove hidrodinamičke i propulzijske karakteristike. Problem je simuliran pomoću računalne dinamike fluida u računalnom paketu OpenFOAM. Matematički model temeljen je na Reynoldsovim osrednjenim Navier-Stokesovim jednadžbama dok je za model turbulencije korišten k-ω SST model. Rezultati simulacija zanošenja broda uspoređeni su s eksperimentalnim podatcima dostupnim u literaturi. Razrađena je metoda procjene potrebnog otklona kormila i kuta zanošenja broda prilikom plovidbe potpomognute vjetrom pri brzini od 12,5 čvorova. Nadalje, provedene su simulacije vlastitog pogona kako bi se dobio bolji uvid u iznose sila i momenata koje djeluju na brod, pri čemu je brodski vijak idealiziran tzv. modelom Actuator disk. Analizirane su sile i momenti koje djeluju na brod sa i bez vlastitog pogona te je dan osvrt na učinak vlastitog pogona prilikom određivanja sila i momenata. Isto tako analiziran je utjecaj uključivanja neotklonjenog kormila na hidrodinamičke značajke te je dana usporedba sa simulacijama bez prisutnosti kormila. Naposljetku, analiziran je vlastiti pogon broda u realnim uvjetima plovidbe s vjetrom potpomognutom propulzijom s ciljem izračuna dovedene snage brodskom vijku što je direktno povezano s potrošnjom goriva. Utvrđeno je kako jedra generiraju veliku bočnu silu na brod što uzrokuje njegovo zanošenje i promjenu simetričnog opstrujavanja fluida oko trupa uzrokujući zakretanje broda u vjetar. Zakretanje je potrebno ispraviti otklonom kormila dok će spomenuto zanošenje i otklon kormila utjecati na povećanje otpora broda. Ipak, pokazano je kako će se uz određeno povećanje hidrodinamičkog otpora ostvariti značajne uštede u snazi dovedenoj brodskom vijku.

Abstract (english)

This thesis involved a numerical study of the impact of wind-assisted propulsion on the hydrodynamic and propulsion characteristics of a bulk carrier. The problem was simulated using computational fluid dynamics by means of the OpenFOAM software package. The mathematical model was based on the Reynolds-averaged Navier-Stokes equations, and the k-ω SST turbulence model was used. Ship heeling simulations were validated against available experimental data from the literature. A method for estimating the required rudder deflection and ship drift angle during wind-assisted sailing at a speed of 12.5 knots was developed. Furthermore, self-propulsion simulations were conducted to obtain more realistic values of the forces and moments acting on the ship, with the propeller being modeled as an Actuator disk. The forces and moments acting on the ship with and without self-propulsion were analyzed, and a discussion on the use of self-propulsion in determining these forces and moments was provided. The influence of incorporating an un-deflected rudder on the hydrodynamic characteristics was also analyzed, and a comparison was made with simulations without the presence of the rudder. Finally, the self-propulsion of the ship under real wind-assisted propulsion conditions was analyzed to calculate the delivered power to the ship’s propeller, which is directly related to fuel consumption. It was demonstrated that sails generate a significant lateral force on the ship, causing it to drift and altering the symmetric flow of fluid around the hull, resulting in the ship yawing into the wind. The veering needs to be corrected by rudder deflection, which in turn affects an increase in the ship’s resistance. Nevertheless, it was shown that significant fuel savings can still be achieved despite a substantial increase in hydrodynamic resistance.

• Keywords: brod za rasuti teret; RDF – Računalna dinamika fluida; Navier-Stokesove jednadžbe; k-ω SST model turbulencije; Actuator disk; vjetrom potpomognuta propulzija; zanošenje; otklon kormila; hidrodinamika.
• Keywords (english): bulk carrier; CFD – Computational Fluid Dynamics; Navier-Stokes equations; k- ω SST turbulence model; Actuator disk; wind-assisted propulsion; yawing; rudder deflection; hydrodynamics.
• Language: croatian
• URN:NBN: urn:nbn:hr:235:439004
• 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: 2023-12-01 11:25:07