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http://dx.doi.org/10.9725/kstle.2016.32.4.132

Friction Power Loss Reduction for a Marine Diesel Engine Piston  

An, Sung Chan (Engine & Machinery Research Institute, Hyundai Heavy Industries Co., Ltd.)
Lee, Sang Don (Engine & Machinery Research Institute, Hyundai Heavy Industries Co., Ltd.)
Son, Jung Ho (Engine & Machinery Research Institute, Hyundai Heavy Industries Co., Ltd.)
Cho, Yong Joo (School of Mechanical Engineering, Pusan National University)
Publication Information
Tribology and Lubricants / v.32, no.4, 2016 , pp. 132-139 More about this Journal
Abstract
The piston of a marine diesel engine works under severe conditions, including a combustion pressure of over 180 bar, high thermal load, and high speed. Therefore, the analyses of the fatigue strength, thermal load, clamping (bolting) system and lubrication performance are important in achieving a robust piston design. Designing the surface profile and the skirt ovality carefully is important to prevent severe wear and reduce frictional loss for engine efficiency. This study performs flexible multi-body dynamic and elasto-hydrodynamic (EHD) analyses using AVL/EXCITE/PU are performed to evaluate tribological characteristics. The numerical techniques employed to perform the EHD analysis are as follows: (1) averaged Reynolds equation considering the surface roughness; (2) Greenwood_Tripp model considering the solid_to_solid contact using the statistical values of the summit roughness; and (3) flow factor considering the surface topology. This study also compares two cases of skirt shapes with minimum oil film thickness, peak oil film pressure, asperity contact pressure, wear rate using the Archard model and friction power loss (i.e., frictional loss mean effective pressure (FMEP)). Accordingly, the study compares the calculated wear pattern with the field test result of the piston operating for 12,000h to verify the quantitative integrity of the numerical analysis. The results show that the selected profile and the piston skirt ovality reduce friction power loss and peak oil film pressure by 7% and 57%, respectively. They also increase the minimum oil film thickness by 34%.
Keywords
asperity contact; EHD(elasto-hydrodynamic); friction power loss; minimum oil film thickness(MOFT); skirt profile;
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  • Reference
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