seawater fluid structure interaction · pdf file2centre of marine engineering, politeknik...

4
VOL. 12, NO. 4, FEBRUARY 2017 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences ©2006-2017 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 1344 SEAWATER FLUID STRUCTURE INTERACTION ANALYSIS THROUGH BEARING LINER STRUCTURAL MODIFICATION APPROACH Saw, C. L. 1 , Syed Amear S. A. 2 , Choong, C. G. 1 and Shahril, J. 2 1 Centre of Air Conditioning and Refrigeration, Politeknik Ungku Omar, Ipoh, Perak, Malaysia 2 Centre of Marine Engineering, Politeknik Ungku Omar, Ipoh, Perak, Malaysia E-Mail: [email protected] ABSTRACT Wide replacement of oil lubrication for marine journal bearing to seawater lubricated is to protect marine aquatic from rapid oil leak and intentionally oil waste pollution. The cause of bearing liner and propeller shaft wear and eroded are the low viscosity of seawater, marine growth, seawater flow and start up friction that disrupt the hydrodynamics film of lubricant. 3D journal bearing model has been developed with 10, 15, 20 grooves liner structural modification and inclusive of dimple instead of plain journal bearing. The Fluid Structure Interaction simulation shows that 20 grooves liner with dimples has the least deformation with von mises stress 717.37 Pa due to lubrication by dimples lubricant. The more grooves and dimples shows that more cooling effect by seawater flowing through the bearing by reducing the friction wear and increase the hydrodynamic pressure. Keywords: fluid structure interaction, 3D computational simulation, hydrodynamic journal bearing, dimple liner structural. INTRODUCTION The awareness to reduce the amount of oil lubrication pollution released to the environment have been a great concerned in rotating machinery design. Liquid-water based lubrication such as water and seawater have been identified as a green and environmental friendly to replace mineral oil and bio-oil based lubrication. The uses of water-lubricated journal bearings in rotating machinery in shipbuilding, industrial machinery and equipment, transportation industry, food industry and pharmaceutical industry is widely applied [1-4]. The disadvantage of water as a lubricant is that its viscosity is much lower than of oil and grease [5]. It contributes to low hydrodynamics fluid of a water- lubricated plain bearing. Most of the researchers’ investigations were focus on theories and experimental measurement of hydrodynamics bearing. With the advancement in the computer technology, many researchers have adopted computational fluid dynamics (CFD) simulation in their investigation [6-8]. Recent commercial software with CFD package is a suitable software to perform numerical simulation and analyzing the flow problem. However, there is important by interacting fluid dynamics and structural dynamics in numerical simulation. Meruane et al. [9] proposed three-dimensional plain journal bearings transient simulation with fluid- structure interaction (FSI) but cavitations was not considered in their studies. Shenoye et al. [10] performed an elastohydrodynamic lubrication analysis on a journal bearing using commercial software ANSYS/FLOTRAN incorporating the FSI technique and cavitation was included in the study. The above studies mainly focus on the operating properties such as pressure and temperature distribution, minimum film thickness and dynamic characteristic of misaligned journal bearings. Another cause of bearing failure is due to misalignment of shaft and extensive force propulsion of propeller that lead to failure of bearing as shown in Figure-1. In this paper, modification on the bearing lining structure has been considered as another method to reduce or eliminate bearing wear and failure. The fluid-structure interaction (FSI) simulation is considered to investigate the fluid dynamics and structural deformation of the modified bearing lining structure to reduce the wear and failure. Figure-1. Bearing worn out [Courtesy picture by Micro precision Eng. and Serv.Sdn. Bhd.] SIMULATION MODEL AND SIMULATION SETUP Assumptions and journal bearing assembly Three dimensional assembly of journal bearing as shown in Figure-1. The components of journal bearing assembly as listed in Table-2. Steady state analysis is used to find hydrodynamic forces without considering the vapour cavitation. The flow is set turbulent by using k- epsilon technique, isothermal and moving wall is applied on the journal and bearing. The operating pressure is set at atmospheric pressure that is 101325 Pa. One side of the water lubricating film clearance is used as inlet and the other side as an outlet. The pressure at the inlet and outlet

Upload: vudien

Post on 31-Mar-2018

215 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: SEAWATER FLUID STRUCTURE INTERACTION · PDF file2Centre of Marine Engineering, Politeknik Ungku Omar, Ipoh, Perak, Malaysia ... from rapid oil leak and intentionally oil waste

VOL. 12, NO. 4, FEBRUARY 2017 ISSN 1819-6608

ARPN Journal of Engineering and Applied Sciences

©2006-2017 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

1344

SEAWATER FLUID STRUCTURE INTERACTION ANALYSIS THROUGH BEARING LINER STRUCTURAL MODIFICATION APPROACH

Saw, C. L.1, Syed Amear S. A.2, Choong, C. G. 1 and Shahril, J. 2

1Centre of Air Conditioning and Refrigeration, Politeknik Ungku Omar, Ipoh, Perak, Malaysia 2Centre of Marine Engineering, Politeknik Ungku Omar, Ipoh, Perak, Malaysia

E-Mail: [email protected]

ABSTRACT Wide replacement of oil lubrication for marine journal bearing to seawater lubricated is to protect marine aquatic from rapid oil leak and intentionally oil waste pollution. The cause of bearing liner and propeller shaft wear and eroded are the low viscosity of seawater, marine growth, seawater flow and start up friction that disrupt the hydrodynamics film of lubricant. 3D journal bearing model has been developed with 10, 15, 20 grooves liner structural modification and inclusive of dimple instead of plain journal bearing. The Fluid Structure Interaction simulation shows that 20 grooves liner with dimples has the least deformation with von mises stress 717.37 Pa due to lubrication by dimples lubricant. The more grooves and dimples shows that more cooling effect by seawater flowing through the bearing by reducing the friction wear and increase the hydrodynamic pressure. Keywords: fluid structure interaction, 3D computational simulation, hydrodynamic journal bearing, dimple liner structural. INTRODUCTION

The awareness to reduce the amount of oil lubrication pollution released to the environment have been a great concerned in rotating machinery design. Liquid-water based lubrication such as water and seawater have been identified as a green and environmental friendly to replace mineral oil and bio-oil based lubrication. The uses of water-lubricated journal bearings in rotating machinery in shipbuilding, industrial machinery and equipment, transportation industry, food industry and pharmaceutical industry is widely applied [1-4].

The disadvantage of water as a lubricant is that its viscosity is much lower than of oil and grease [5]. It contributes to low hydrodynamics fluid of a water-lubricated plain bearing. Most of the researchers’ investigations were focus on theories and experimental measurement of hydrodynamics bearing. With the advancement in the computer technology, many researchers have adopted computational fluid dynamics (CFD) simulation in their investigation [6-8]. Recent commercial software with CFD package is a suitable software to perform numerical simulation and analyzing the flow problem.

However, there is important by interacting fluid dynamics and structural dynamics in numerical simulation. Meruane et al. [9] proposed three-dimensional plain journal bearings transient simulation with fluid-structure interaction (FSI) but cavitations was not considered in their studies. Shenoye et al. [10] performed an elastohydrodynamic lubrication analysis on a journal bearing using commercial software ANSYS/FLOTRAN incorporating the FSI technique and cavitation was included in the study. The above studies mainly focus on the operating properties such as pressure and temperature distribution, minimum film thickness and dynamic characteristic of misaligned journal bearings. Another cause of bearing failure is due to misalignment of shaft and extensive force propulsion of propeller that lead to failure of bearing as shown in Figure-1. In this paper,

modification on the bearing lining structure has been considered as another method to reduce or eliminate bearing wear and failure. The fluid-structure interaction (FSI) simulation is considered to investigate the fluid dynamics and structural deformation of the modified bearing lining structure to reduce the wear and failure.

Figure-1. Bearing worn out [Courtesy picture by Micro precision Eng. and Serv.Sdn. Bhd.]

SIMULATION MODEL AND SIMULATION SETUP Assumptions and journal bearing assembly

Three dimensional assembly of journal bearing as shown in Figure-1. The components of journal bearing assembly as listed in Table-2. Steady state analysis is used to find hydrodynamic forces without considering the vapour cavitation. The flow is set turbulent by using k-epsilon technique, isothermal and moving wall is applied on the journal and bearing. The operating pressure is set at atmospheric pressure that is 101325 Pa. One side of the water lubricating film clearance is used as inlet and the other side as an outlet. The pressure at the inlet and outlet

Page 2: SEAWATER FLUID STRUCTURE INTERACTION · PDF file2Centre of Marine Engineering, Politeknik Ungku Omar, Ipoh, Perak, Malaysia ... from rapid oil leak and intentionally oil waste

VOL. 12, NO. 4, FEBRUARY 2017 ISSN 1819-6608

ARPN Journal of Engineering and Applied Sciences

©2006-2017 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

1345

boundaries is set as 0 Pa (gauge pressure) since the bearing is fully submerged inside the lubricant. The outer surface of the water lubricating film that is bearing is modelled as a “moving wall” and the inner surface is modelled as a “stationary wall” with a rotational speed equal journal. A no-slip condition is imposed on the two walls.

Figure-2. Journal bearing assembly.

Table-1. Properties of the journal bearing assembly [11-12].

Thermohydrodynamcis is not considered in this study. Fluid-structure analysis by using fluent and static structural incorporated software in ANSYS has been deploy on the 3Dimensional model. Energy model and k-epsilon model with 1x10-6 computational residual error is used to simulate FSI journal bearing. SIMPLEC discretization technique couple with PRESTO pressure is used to solve the fluid dynamics in the steady state condition. While, on structural analysis, pressure generated from fluent is imported to static structural interface by solving the finite element method as shown in Figure-3. Speed of 700 rpm is used in this study since this is the free running engine at first ignition. During the starting of engine, friction wear between bearing liner and shaft will happen due to empty lubricant and lubricant just started to flow into stern tube.

Figure-3. Methodology of simulation process. Governing equations for fluid structure interaction

The results of k-epsilon turbulent flow and isothermal are present by solving using conservation equations for mass and momentum. While, in Fluid Structure Interaction, fluid flow exerts a pressure on solid structure causing it to deform. Deformation of the bearing was analysed involved governing finite element equation:

[Ms] {Mf} + [Ks] {U} = [Fs] + [R] {P}

Where [Ms] is the structural mass matrix; [Mf] is the fluid mass matrix; [Fs] and [Ff] is the structural and fluid force matrix; [R] is a coupling matrix that represents the effective surface area associated with each node in fluid structure interface.

Page 3: SEAWATER FLUID STRUCTURE INTERACTION · PDF file2Centre of Marine Engineering, Politeknik Ungku Omar, Ipoh, Perak, Malaysia ... from rapid oil leak and intentionally oil waste

VOL. 12, NO. 4, FEBRUARY 2017 ISSN 1819-6608

ARPN Journal of Engineering and Applied Sciences

©2006-2017 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

1346

RESULTS AND DISCUSSIONS Cong et al. (2013) [13] and Jing et al (2010) [14]

investigated dimple and micro dimple effect on hydrodynamics of bearing. The simulation on single dimple using CFD analysis has showed pressure is well distributed on the bearing and friction coefficient decreased due to reducing the friction force. Only single dimple is simulated since other dimple is identically the same across the geometry of the bearing.

In this study, 3D bearing model has been developed to investigate further the effect of dimple on bearing liners. The reason inclusion of dimples is that the remaining of the lubricant left inside the dimples cavity help to reduce shaft friction wear during the starting of the engine. Five (5) modification models on bearing grooves have been proposed. Table-2 listed the stress behaviour of the bearing, while Table-3 listed the deformation of the bearing. Modification A3 that is 20 grooves liners bearing reduce more stress and deformation of bearing compared to modification A1 and A2. As more grooves provide more cooling effect by flowing more seawater through the bearing. Modification A5 inclusive of 10 dimples in a row at 100mm distance between each other has the least stress (717.37 Pa) and deformation (1.85x10-9 m).

Table-2. Von-mises stress on modification model.

Table-3. Deformation on modification model.

Hence, pressure exerted on the bearing liners varies from model A1 to model A5 as listed in Table-4. Model A5 having the highest pressure built-up on the liners surface and edge of the dimples that reduces the sliding friction due to evenly distributed pressure.

Page 4: SEAWATER FLUID STRUCTURE INTERACTION · PDF file2Centre of Marine Engineering, Politeknik Ungku Omar, Ipoh, Perak, Malaysia ... from rapid oil leak and intentionally oil waste

VOL. 12, NO. 4, FEBRUARY 2017 ISSN 1819-6608

ARPN Journal of Engineering and Applied Sciences

©2006-2017 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

1347

Table-4. Total pressure on modification model.

CONCLUSIONS

Grooves in bearing and dimples on the bearing liners proves to improve lubrication that reduced the friction wear. A3 and A5 models are proposed as good modification model based on the simulated results. ACKNOWLEDGEMENTS

Politeknik Ungku Omar’s researcher team would like to thanks Micro precession Engineering Sdn. Bhd. for providing the information data and research opportunities on the stern tube bearing of marine vessel REFERENCES [1] H. Hirani, M. Verma. 2009. Tribological study of

elastomeric bearings for marine propeller shaft system. Tribol Int. 42:378–390.

[2] W. Litwin. 2009. Water-lubricated bearings of ship propeller shafts-problems, experimental tests and theoretical investigations. Pol Marit Res.16:42–50.

[3] B. A. Lingwall, T. N. Sexton, C. H. Cooley. 2013.

Polycrystalline diamond bearing testing for marine hydrokinetic application. Wear. 302:1514–1519.

[4] B. D. Heberley. 2013. Advances in hybrid water-

lubricated journal bearings for use in ocean vessels [Ph.D.]. Ann Arbor, USA: Massachusetts Institute of Technology.

[5] Yamakiri Hiroki, Sasaki Shinya, Kurita Tsuneo,

SashimaNagayoshi. 2011. Effects of laser surface texturing on friction behaviour of silicon nitride under lubrication with water. Tribol Int. 44:579–584.

[6] H. Montazeri. 2008. Numerical analysis of

hydrodynamic journal bearings lubricated with ferrofluid. Proc Inst MechEng, Part J: J EngTribol. 222:51–60.

[7] K. P. Gertzos, P. G. Nikolakopoulos, C. A.

Papadopoulos. 2008. CFD analysis of journal bearing hydrodynamic lubrication by Bingham lubricant. Tribol Int. 41:1190–1204.

[8] P. Y. P. Chen, E. J. Hahn. 1998. Use of computational

fluid dynamics in hydrodynamic lubrication. Proc Inst MechEng, Part J: J EngTribol. 212:427–436.

[9] V. Meruane, R. Pascual. 2008. Identification of

nonlinear dynamic coefficients in plain journal bearings. Tribology International. 41:743–754.

[10] S. B. Shenoy, R. Pai, D. Rao, R. B. Pai. 2009. Elasto-

hydrodynamic lubrication analysis of full 360 journal bearing using CFD and FSI techniques. World Journal of Modelling and Simulation. 5:315–320.

[11] Y. C. Kang, Y. O. Seung, A. S. Seung, W. L. Jun, I.

L. Jun, S. K. Seong. 2015. Study of the endurance performance of composite journal bearings under the oil cut situation. Composite Structure. 134:772-781.

[12] M. Stephen and P. Robert. 2012, Seawater lubricated

polymer journal bearings for use in wave energy converters. Renewable Energy. 39: 463-470.

[13] C. Shen, M. M. Khonsari Effect of dimple's internal

structure on hydrodynamiclubrication. Tribol Lett 2013; 52(3):415–30.

[14] H. Jing, F. Liang, J. Sun and S. Ge. 2010.

Hydrodynamic lubrication of Microdimple surface using three-dimensional CFD. Tribology Transactions. 53(6):860-870.