Suyla yağlamalı polimer gemi stern tüp yataklarının tribolojik performansının farklı yiv tasarımlarıyla iyileştirilmesi
Thesis Type: Postgraduate
Institution Of The Thesis: Ataturk University, Fen Bilimleri Enstitüsü, Makine Mühendisliği Anabilim Dalı, Turkey
Approval Date: 2025
Thesis Language: Turkish
Student: MUSAB ÇULLU
Supervisor: Halim Kovacı
Open Archive Collection: AVESIS Open Access Collection
Abstract:Purpose: Recently, the increase in environmental awareness and the enactment of new legal measures have led to an increase in interest in environmentally friendly technologies. The increasing interest in environmentally friendly technologies has led to an increase in the use of water-lubricated polymer bearings instead of traditional petroleum-derived mineral oil-lubricated bearings, especially in the shipbuilding sector. Water-lubricated polymer bearings; In addition to being environmentally friendly, have many advantages over mineral oil-lubricated bearings, such as low cost, high corrosion resistance, ability to damp vibration and ability to operate well in limited lubrication regimes. However, in practical applications, rapid wear and shaft failure cases due to bearing bush wear have frequently occurred in such bearings in recent years. In this study, it was aimed to investigate the bearing model with the highest hydrodynamic load carrying capacity and the lowest fluid shear stress in order to ensure long-term and safe operation of water-lubricable polymer stern tube bearings using different groove designs. Method: Bearings with 15 different groove types were modeled with SOLIDWORKS software by using parameters such as the position, number and orientation of the grooves relative to the bearing while keeping the groove geometry constant. Then, Computational Fluid Dynamics (CFD) analyses were performed by applying Reynolds boundary conditions with ANSYS Fluent software for the lubricating fluid form remaining between the polymer bearing bush and the propeller shaft. Findings: It has been observed that the number of cooling and desilting grooves used in polymer stern tube bearings, their position relative to the bearing and their axial or helical condition, such as parameters, significantly affect the hydrodynamic load carrying capacity and fluid shear stress of the bearing. It has been observed that grooves placed in the low liquid film pressure region of the bearing, depending on the direction of rotation of the shaft, increase the hydrodynamic load carrying capacity of the bearing, while grooves placed in the region where high liquid film pressure occurs reduce the hydrodynamic load carrying capacity of the bearing. It has been observed that helical grooves placed in the bearing bushes, regardless of their position and number relative to the bearing, increase the fluid shear stress, and therefore reduce the bearing performance. It has been observed that axial grooves placed just opposite the high liquid film pressure of the bearing reduce the fluid shear stress of the bearing, and therefore increase the bearing performance. Results: It was concluded that the hydrodynamic load carrying capacity of the bearing can be increased by using different groove designs and the performance of the bearing can be improved by reducing the fluid shear stress formed in the bearing. It was observed that the best bearing model in terms of hydrodynamic load carrying capacity is the rhombic patterned bearing model (Model-14) obtained by placing clockwise and counterclockwise helical grooves only in the low pressure region of the bearing, and the bearing model with the lowest fluid shear stress and therefore the best bearing performance is the bearing model (Model-13) in which axial grooves are placed only in the low pressure region of the bearing. It was concluded that the best bearing model in terms of hydrodynamic load carrying capacity and bearing performance within the scope of bearing optimization is Model-13.