Analysis of the shafting system alignment for a bulk carrier fleet

Θεοφίλης, Παναγιώτης; Theofilis, Panagiotis

dc.contributor.author	Θεοφίλης, Παναγιώτης	el
dc.contributor.author	Theofilis, Panagiotis	en
dc.date.accessioned	2022-11-18T10:01:36Z
dc.date.available	2022-11-18T10:01:36Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/56161
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.23859
dc.rights	Αναφορά Δημιουργού-Όχι Παράγωγα Έργα 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nd/3.0/gr/	*
dc.subject	Αξονικό Σύστημα	el
dc.subject	Ευθυγράμμιση Άξονα	el
dc.subject	Κατακόρυφη θέση εδράνου	el
dc.subject	Ελαστική Γραμμή	el
dc.subject	Αντίδραση Στήριξης	el
dc.subject	Shafting System	en
dc.subject	Shaft Alignment	en
dc.subject	Bearing Offset	en
dc.subject	Deflection Curve	en
dc.subject	Bearing Reaction Force	en
dc.title	Analysis of the shafting system alignment for a bulk carrier fleet	en
heal.type	bachelorThesis
heal.classification	Marine Engineering	en
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2022-07-20
heal.abstract	The propulsion system may suffer various failures through a ship’s life span. The failures may occur on the shaft lines, the crankshaft or the bearings, mainly due to excessive load. Bearings may also suffer from vibrations when unloaded or lightly loaded. A proper shaft alignment will lead to smooth distribution of bearing loads and smooth elastic deformation of the shafting system, thus reducing the probability of failures and increasing the reliability of the system. Although shaft alignment is a process studied for decades, classification societies released updated enhanced shaft alignment regulations a few years ago, as ships became larger and more flexible causing shorter and more stiff shaft lines that may also be significantly affected by hull deflections, which impact negatively along with vibrations the propulsion system. In this study, a dimension analysis of the propulsion system of a bulk carrier fleet is carried out. Specifically, the fleet consists of 17 bulk carriers of different size categories. The analysis contains lengths and diameters of the three (3) shafts that consist of the shafting system (propeller shaft, intermediate shaft and main engine shaft) and their respective flanges for each vessel of the fleet. The detailed shafting system of one of the vessels of the fleet is studied more extensively. The vessel is a typical 82k DWT bulk carrier powered by a 2-stroke Diesel engine. The shaft alignment process for this vessel was carried out by ABS for a specific propeller load and set of vertical bearing offsets (initial offsets) and the results were compared utilizing an in-house software for the same conditions. The shafting system is modelled as a beam divided into smaller segments and the bearings are modelled as supporting points. Radial shaft loads, thermal expansion of the engine and thrust eccentricity caused by the propeller are taken into account. The results (reaction forces, bending moments, etc.) are calculated using matrix analysis. Simulations are executed for 4 propeller immersion conditions (propeller in air, half immersed, 75% immersed, fully immersed) and for various new offsets combinations, which deviate with a specific manner from the initial offsets. The scenarios are classified as; (i) acceptable, (ii) marginal and (iii) not acceptable, in accordance with ABS regulations for the reaction forces and three (3) offset configurations (basis offsets) lead to results that meet the regulations. Simulations are executed for smaller deviations from the basis offsets of those three (3) different offset combinations and for the all propeller loading conditions. Conclusions are drawn based on the above. Concerning the dimension analysis, comparisons between the ratios of the dimensions of the shaft and the flanges are made. Concerning the ship specific study, propeller immersion and vertical offsets of the bearings lead to the classification of various scenarios according to IACS regulations for acceptable bearing reaction forces. Depending on the occasion, conclusions can be made about the behavior of the elastic line of the shaft and the behavior of bearing reactions.	en
heal.advisorName	Παπαδόπουλος, Χρήστος	el
heal.committeeMemberName	Λυρίδης, Δημήτριος	el
heal.committeeMemberName	Παπαλάμπρου, Γεώργιος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Ναυπηγών Μηχανολόγων Μηχανικών	el
heal.academicPublisherID	ntua
heal.fullTextAvailability	false