Utjecaj približno određenih značajki mase broda na dodatni otpor na valovima

master's thesis

• Title (english): Influence of the approximated mass characteristics of a ship on the added resistance in waves
• Author: Petra Komazec
• Mentor: Nastia Degiuli (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2017-07-21, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Shipbuilding

Abstract

Dodatni otpor na valovima važno je predvidjeti već u ranoj fazi projektiranja broda. Povećanje otpora uzrokovano valovima utječe na brzinu broda i potrošnju goriva te može predstavljati značajan problem s aspekta očuvanja okoliša. Dodatni otpor broda na valovima je nelinearna hidrodinamička sila drugog reda koja ovisi o gibanjima broda, a nastaje uslijed interakcije valnog sustava broda i nailaznih valova.

U radu je dana teorijska osnova dodatnog otpora broda na valovima te rezultati numeričkog proračuna dodatnog otpora na pravilnim valovima za tri različite forme broda. Numerički proračuni provedeni su u programskom paketu HydroSTAR, koji se temelji na linearnoj teoriji potencijalnog strujanja. Numerički dobiveni rezultati dodatnog otpora broda na valovima uspoređeni su s eksperimentalnim podacima dostupnim u literaturi. Osim pravilnih valova u pramac, dodatni otpor određen je i za različite kutove nailaska valova.

Značajke mase broda su nužni ulazni parametri za proračun dodatnog otpora broda na valovima, koji često nisu poznati u preliminarnoj fazi projektiranja. Stoga ih je potrebno što točnije procijeniti kako bi rezultati dodatnog otpora broda na valovima bili što pouzdaniji. Iz tog razloga, u radu su prikazane metode određivanja položaja težišta mase broda po visini i radijusa tromosti mase te je analiziran njihov utjecaj na dodatni otpor broda na valovima. Budući da brod provede oko 40-50% svog radnog vijeka u balastnom stanju, dodatni otpor broda na valovima proračunat je i za balastno stanje te su dobiveni rezultati uspoređeni s rezultatima dodatnog otpora broda na valovima za stanje punog opterećenja.

Abstract (english)

It is important to predict the added resistance in waves already in early stage of ship design. The increase in resistance due to waves affects the ship speed and fuel consumption and can represent significant problem from the aspect of environmental protection. The added resistance in waves is the nonlinear hydrodynamic force of the second order which depends on the ship motions and is caused by the interaction of the ship wave system and the incoming waves.

The paper provides a theoretical basis for the added resistance in waves and the results of the numerical calculation of the added resistance in regular waves for three different ship forms. The numerical calculations are carried out utilizing HydroSTAR program package, based on the linear theory of potential flow. The numerical results of the added resistance in waves are compared with the experimental data available in the literature. In addition to regular head waves, the added resistance is also determined for different incident angles.

The ship mass characteristics are necessary input parameters for calculation of the added resistance in waves and they are often unknown in the preliminary design stage. Therefore, they need to be accurately evaluated to ensure that the results of the added resistance in waves are as reliable as possible. For this reason, the methods for the determination of center of gravity and the gyration radii are presented within this paper and their effect on the added resistance in waves is analysed. Since ship spends approximately 40-50% of her total voyage time in the ballast condition, the added resistance in waves is calculated for the ballast condition as well. The obtained results are compared with the results of added resistance in waves for the full load condition.

• Keywords: dodatni otpor na valovima; potencijalno strujanje; valna opterećenja; pomorstvenost; QTF; sila zanošenja
• Keywords (english): added resistance in waves; potential flow; wave loads; seakeeping; QTF; drift force
• Language: croatian
• URN:NBN: urn:nbn:hr:235:298422
• Study programme: Title: Naval Architecture; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka brodogradnje (magistar/magistra inženjer/inženjerka brodogradnje)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 20:01:07