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- Title
- Three dimensional analysis of the gas flow in piston ring pack
- Creator
- Kharazmi, Ali
- Date
- 2017
- Collection
- Electronic Theses & Dissertations
- Description
-
"Cylinder-kit dynamics design in an internal combustion engine is highly relevant for the engine performance characteristics, durability and reliability. Since the middle of the 20th century, researchers have been using numerical models to describe the processes that occur in a ring pack. Because it is difficult and extremely costly to conduct experiments on every series of engines to check for the blow-by and oil consumption, a computational analysis can be performed on the ring pack to...
Show more"Cylinder-kit dynamics design in an internal combustion engine is highly relevant for the engine performance characteristics, durability and reliability. Since the middle of the 20th century, researchers have been using numerical models to describe the processes that occur in a ring pack. Because it is difficult and extremely costly to conduct experiments on every series of engines to check for the blow-by and oil consumption, a computational analysis can be performed on the ring pack to study the blow-by and oil-consumption characteristics. In this dissertation a 3D CFD simulation model is introduced to analyze the flow between the cylinder liner and the piston. This model allows for calculation of the piston assembly with consideration of the ring dynamics, transient boundary conditions for combustion chamber pressure and temperature as well as thermal distortion of the piston and liner. The determination of the complex geometry of the cylinder-kit is established in a STL (STereoLithography) format by considering the complicated geometrical details of the ring pack such as thermal distortion of piston and liner, ring twist and ring/groove conformability. The blow by and blow back is numerically calculated for a small bore cylinder operating at 2000 RPM and verified by the results of commercially available 1D models. The calculated velocity filed shows substantial circumferential flow in the piston ring pack that is dominated by the ring and groove geometry as well as the relative position of the rings end gap. It is found that the amount of gas that flows back to the combustion chamber increases when the in-cylinder pressure trace decreases from its peak value. The knowledge from this study can be used as a basis for further multiphase calculations containing oil flow such as oil consumption, oil evaporation and eventually cylinder-kit wear."--Page ii.
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- Title
- Computational analysis of piston ring wear and oil consumption for an internal combustion engine
- Creator
- Chui, Boon-Keat
- Date
- 2001
- Collection
- Electronic Theses & Dissertations
- Title
- Ring pack behavior and oil consumption modeling in ic engines
- Creator
- Ejakov, Mikhail Aleksandrovich
- Date
- 1998
- Collection
- Electronic Theses & Dissertations
- Title
- Numerical modeling of the power cylinder system for internal combustion engine with an emphasis on ring pack design
- Creator
- Cheng, Chao (Mechanical engineer)
- Date
- 2014
- Collection
- Electronic Theses & Dissertations
- Description
-
Modeling the piston ring behavior is crucial for the engine power cylinder system. The dynamic and thermal characteristics directly affect engine performance, e.g. frintion loss, wear, blowby loss, etc. This dissertation describes a numerical model of the power cylinder system focusing on the ring pack design. A three-dimensional piston ring model is developed using finite element method. The model predicts the piston ring conformability with the cylinder wall as well as the separation gap...
Show moreModeling the piston ring behavior is crucial for the engine power cylinder system. The dynamic and thermal characteristics directly affect engine performance, e.g. frintion loss, wear, blowby loss, etc. This dissertation describes a numerical model of the power cylinder system focusing on the ring pack design. A three-dimensional piston ring model is developed using finite element method. The model predicts the piston ring conformability with the cylinder wall as well as the separation gap between the interfaces. In addition, the ring model also predicts the interaction between the ring and piston groove sides. This means, the ring axial lift, twist, contact with the groove sides along the circumferential direction are all calculated simultaneously with the radial conformability prediction. The numerical model is then verified through experiment measurement. This validation includes a ring tension force measurement as well as a light-tightness measurement. Good agreement has been found between the measured and calculated result. Thermal load is believed having significant influence on the ring pack performance, especially for the top compression ring, which is under the most severe operating condition. The thermal load influences are included in the model. In addition, a new lubrication model is implemented to the existing model with the consideration of flow factor for the ring pack lubrication and tribology analysis. A simulation study of the second ring dynamics for a modern diesel engine is presented. Two phenomena are focused for this study, one is the second ring fluttering and the other is ring collapse. Both these phenomena are closely related to gas dynamics and could result in engine blowby increase. The mechanism and the conditions at which these phenomena occur are given. The second ring dynamic behavior over an engine cycle is then studied considering 3D effect. The contact forces, in both radial and axial directions, and the twist angles can be found at each engine crank angle. The piston ring model provides the geometry for three-dimensional gas dynamics analysis. In addition to the gas flow paths that the current two-dimensional models predict, including through the ring end gap, through the ring-groove sides as ring flutters, through the ring front face when ring radially collapses, gas can flow through an additional path across the ring. This gas flow path is formed due to the variance of ring axial displacements along the circumference. The variant lift occurs for rings with asymmetric cross-sections. Even for rings with symmetric cross-section, the ring can also undergo different circumferential lift due to influences like piston secondary motion. When this different circumferential lift occurs, gas can flow from the piston land above the ring, through the crevice between the ring-groove sides, to the volume behind the ring for the ring segment that stays bottom seated. The gas can travel circumferentially through the volume behind the ring, until a point that the ring segments lift and stay top seated against the groove top side. Then the gas can flow from the volume behind the ring, through the crevice between the ring-groove bottom sides, to the piston land below the ring.
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- Title
- Development and analysis of a fire ring wear model for a piston engine
- Creator
- Chung, Yooseok
- Date
- 1992
- Collection
- Electronic Theses & Dissertations