Analiza slobodnih vibracija uređaja za uštedu energije na brodovima

master's thesis

• Title (english): Free vibration analysis of ship energy saving devices
• Author: Hrvoje Brečić
• Mentor: Nikola Vladimir (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2020-07-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Marine Mechanical Engineering

Abstract

Zahtjevi za povećanjem energetske učinkovitosti i ekološke prihvatljivosti danas postaju sve prisutniji u svim granama industrije. Tako se i u brodograđevnoj industriji kontinuirano razvijaju rješenja koja imaju za cilj povećati učinkovitost brodova te smanjiti ukupnu emisiju štetnih plinova.
Jedan od načina postizanja toga cilja jest primjena posebnih hidrodinamički oblikovanih dodataka brodskome trupu koje nazivamo uređajima za uštedu energije.Takvi uređaji trebaju zadovoljiti niz kriterija za uspješnu primjenu na brodu. Jedan od osnovnih kriterija odnosi se na zadovoljavanje povoljnih dinamička svojstava.
U ovome radu provedena je analiza dinamičkih svojstava na primjeru predvrtložnog statora, koji spada u grupu tipičnih uređaja za uštedu energije na brodovima. Analiza se odnosi na proračun slobodnih vibracija pojedinih krila predvrtložnog statora uz usporedbu frekvencija tih vibracija s vibracijama uzbude, s ciljem provjere rizika od rezonancije.
Kao osnovne uzročnike uzbuda, razmatrane su vibracije izazvane radom brodskog vijka i vibracije izazvane odvajanjem vrtloga s profila statora.
Proračun slobodnih vibracija proveden je na dva načina: približnim analitičkim metodama poznatim iz teorije elastičnosti i metodom konačnih elementa koristeći računalni programski paket NASTRAN. Podaci potrebni za provedbu proračuna kao i model za provedbu analize vibracija metodom konačnih elemenata ustupljeni su od brodogradilišta Hyundai Heavy Industries Co., Ltd.

Abstract (english)

The aims to develop innovative technological solutions, which intend to reduce greenhouse gas emissions and contribute to overall energy savings on ships, are continuously under consideration by shipowners and shipbuilders around the world.
In order to reduce the energy consumption of the largest energy consumer on board, Energy Saving Devices (ESD) have been developed, and thus represent a promising option for achieving this goal. ESD devices improve propulsion efficiency based on their hydrodynamic shape that affects the operation of the propeller.
In this thesis, the dynamic characteristics of such a device i.e. a Pre-Swirl Stator (PSS) have been analyzed. On the example of an asymmetric pre-swirl stator for a cargo ship currently being developed by the South Korean shipyard Hyundai Heavy Industries Co., Ltd, the suitability of installing such device from the viewpoint of vibrations has been shown.
The provided dynamic analysis has been done by comparing the vibration frequencies caused by the operation of the propeller and Vortex Induced Vibrations (VIV) with the natural frequencies of the pre-swirl stator.
The analysis of the natural frequencies were calculated by using two different approaches: First, by using approximative analytical equations and second, by using the finite element method on a commercial software NASTRAN. The finite elements model was provided directly by the shipyard.
The effect of the fluid added mass is shown by comparing the first few natural frequencies separately for the pre-swirl stator in air and water.

• Keywords: Uređaji za uštedu energije; Predvrtložni stator; Analiza vibracija; Slobodne vibracije; Vibracije izazvane odvajanjem vrtloga
• Keywords (english): Energy Saving Devices; Pre-Swirl Stator; Vibration analysis; Natural frequency; Vortex Induced Vibrations; VIV
• Language: croatian
• URN:NBN: urn:nbn:hr:235:871859
• 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: 2020-07-10 20:34:19