Effects of Piston Design Parameters on Piston Secondary Motion and Skirt - Liner Friction

2005 ◽  
Vol 219 (6) ◽  
pp. 435-449 ◽  
Author(s):  
S. H. Mansouri ◽  
V. W. Wong
Keyword(s):  
Scaling Laws ◽  
Cylinder Liner ◽  
Design Guidelines ◽  
Design Parameters ◽  
Piston Skirt ◽  
Lubrication Regimes ◽  
Impact Forces ◽  
Crank Angle ◽  
Secondary Motion ◽  
Quantitative Design

In this article, a previously developed and experimentally validated piston secondary motion model has been improved further numerically and applied to understand the detailed interactions between the piston skirt and the cylinder liner for various piston design parameters. The model considers the roughness of the surfaces and the topography of the skirt in both the axial (barrel profile) and circumferential (ovality) directions. Three modes of lubrication: hydro-dynamic, mixed, and boundary lubrication regimes have been considered and the skirt is partially flooded in most cases. Elastic deformation of the skirt is an essential part of the model. In this model, the piston dynamic behaviour and frictional and impact forces are predicted as functions of crank angle and are examined in detail. Parameters investigated include piston skirt profile, piston-to-liner clearance, surface roughness, and oil availability. The results show that some of these parameters have profound effects on the frictional and impact forces at the piston skirt/liner interface, and therefore, they have the potential to optimize the piston frictional power loss. Correlations and non-dimensional scaling laws are developed to illustrate the basic governing phenomena. These results aim to provide a set of quantitative design guidelines.

scholarly journals The Analysis of Secondary Motion and Lubrication Performance of Piston considering the Piston Skirt Profile

2018 ◽  
Vol 2018 ◽  
pp. 1-27 ◽  
Author(s):  
Yanjun Lu ◽  
Sha Li ◽  
Peng Wang ◽  
Cheng Liu ◽  
Yongfang Zhang ◽  
...  
Keyword(s):  
Thermal Deformation ◽  
Work Performance ◽  
Cylinder Liner ◽  
Connecting Rod ◽  
Piston Skirt ◽  
Piston Cylinder ◽  
Lubrication Performance ◽  
Rod System ◽  
Liner System ◽  
Secondary Motion

The work performance of piston-cylinder liner system is affected by the lubrication condition and the secondary motion of the piston. Therefore, more and more attention has been paid to the secondary motion and lubrication of the piston. In this paper, the Jakobson-Floberg-Olsson (JFO) boundary condition is employed to describe the rupture and reformation of oil film. The average Reynolds equation of skirt lubrication is solved by the finite difference method (FDM). The secondary motion of piston-connecting rod system is modeled; the trajectory of the piston is calculated by the Runge-Kutta method. By considering the inertia of the connecting rod, the influence of the longitudinal and horizontal profiles of piston skirt, the offset of the piston pin, and the thermal deformation on the secondary motion and lubrication performance is investigated. The parabolic longitudinal profile, the smaller top radial reduction and ellipticities of the middle-convex piston, and the bigger bottom radial reduction and ellipticities can effectively reduce the secondary displacement and velocity, the skirt thrust, friction, and the friction power loss. The results show that the connecting rod inertia, piston skirt profile, and thermal deformation have important influence on secondary motion and lubrication performance of the piston.

Development of a Piston Secondary Motion Model for Skirt Friction Analysis

2012 ◽  
Author(s):  
Ozgur Gunelsu ◽  
Ozgen Akalin
Keyword(s):  
Operating Conditions ◽  
Design Parameters ◽  
Asperity Contact ◽  
Motion Model ◽  
Film Rupture ◽  
Time Step ◽  
Elastic Deformations ◽  
Oil Film ◽  
Piston Skirt ◽  
Secondary Motion

A comprehensive piston skirt lubrication and secondary motion model that can be used for piston friction simulations was developed based on Greenwood and Tripp’s surface asperity contact model and Patir and Cheng’s modified Reynolds equation with surface flow factors. Oil flow between the skirt-liner clearances was modeled and hydrodynamic and asperity contact pressures around the skirt were calculated. Reynolds boundary conditions were applied to determine the film rupture boundaries and wetted areas. Surface roughness and roughness orientation were included in the model. Due to its important effect on pressure development in the oil film, change in the skirt profile due to elastic deformations was taken into account. Change of the skirt profile due to piston thermal expansion is also calculated using the steady-state temperature distribution of the piston corresponding to the investigated engine running conditions. A piston stiffness matrix obtained by finite element analysis was used to determine the elastic deformations of the piston skirt under the calculated oil film pressures. A two-degree-of-freedom system is formed with the forces and moments calculated by the lubrication model. These forces and moments require a coupled solution with piston position. This is achieved by applying an iterative numerical procedure based on Broyden’s scheme which seeks force and moment balance at each iteration phase making use of time step variation. The effects of various engine operating conditions and piston design parameters on piston secondary motion were investigated. Piston skirt friction force due to hydrodynamic shear forces and metal-to-metal contact is calculated.

Impact of the Piston Secondary Motion on its Slap Force

2014 ◽  
Vol 553 ◽  
pp. 582-587
Author(s):  
Bao Cheng Zhang ◽  
Tong Li ◽  
Hai Fei Zhan ◽  
Yuan Tong Gu
Keyword(s):  
Theoretical Model ◽  
Boundary Conditions ◽  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Cylinder Liner ◽  
Internal Combustion ◽  
Lubricating Oil ◽  
Actual Condition ◽  
Piston Skirt ◽  
Secondary Motion

A theoretical model is developed for the analysis of piston secondary motion. Based on this model, the slap force of a specific L6 diesel engine was compared when considering different boundary conditions, such as lubricating oil on cylinder liner, surface roughness, deformation of cylinder liner and piston skirt. It is concluded that it is necessary to consider the secondary motion of piston in the analysis of the inner excitation for an internal combustion engine. A more comprehensive consideration of the boundary condition (i.e., more close to the actual condition) will lead to a smaller maximum slap force, and among all boundary conditions considered in this paper, the structural deformation of the piston skirt and cylinder liner is the most influential factor. The theoretical model developed and findings obtained in this study will benefit the future analysis and design of advanced internal combustion engine structures.

scholarly journals Research on the influence of key structural parameters on piston secondary motion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haixiang Yang ◽  
Jilin Lei ◽  
Xiwen Deng ◽  
Jun Wen ◽  
Zhigao Wen ◽  
...  
Keyword(s):  
Power Loss ◽  
Structural Parameters ◽  
Cylinder Liner ◽  
Oil Consumption ◽  
Frictional Loss ◽  
Significance Level ◽  
Friction Power ◽  
Piston Skirt ◽  
Secondary Motion ◽  
Response Method

AbstractPiston secondary motion not only influences the side knocking of piston and frictional loss, but also influence the in-cylinder oil consumption and gas blow-by. An inline four-cylinder common rail diesel engine was chosen as the research object. Dynamic simulation model of piston assembly was built based on the piston and cylinder liner temperature field test. The impacts of pinhole offset, liner clearance and piston skirt ovality on piston secondary motion were researched. Based on the surface response method, the influence of multiple factors on friction power loss and slapping energy is estimated. The results indicate that: in-cylinder stress condition of piston will change with its structural parameters, then the secondary motion of piston will be affected as a result. Pinhole offset, liner clearance, piston skirt ovality and the interaction of the latter two all have significant effects on the friction power loss, while the slapping energy is significantly affected by liner clearance. Therefore, the parameters can be designed based on the significance level to optimize the secondary motion characteristics of the piston.

Piston dynamics, lubrication and tribological performance evaluation: A review

2018 ◽  
Vol 21 (5) ◽  
pp. 725-741 ◽  
Author(s):  
Cristiana Delprete ◽  
Abbas Razavykia
Keyword(s):  
Power Loss ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Tribological Performance ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Design Parameters ◽  
Combustion Engines ◽  
Piston Skirt ◽  
Secondary Motion

Mechanical power loss of lubricated and bearing surfaces serves as an attractive domain for study and research in the field of internal combustion engines. Friction reduction at lubricated and bearing surface is one of the most cost-effective ways to reduce gas emission and improve internal combustion engines’ efficiency. This thus motivates automotive industries and researchers to investigate tribological performance of internal combustion engines. Piston secondary motion has prime importance in internal combustion engines and occurs due to unbalanced forces and moments in a plane normal to the wrist pin axis. Consequently, piston executes small translations and rotations within the defined clearance during the piston reciprocating motion. Mechanical friction power loss and lubrication at piston skirt/liner and radiated engine noise are dramatically affected by piston secondary dynamics. The lubrication mechanism, piston secondary motion and tribological performance are affected by piston design parameters (piston/liner clearance, wrist pin offset, skirt profile, etc.), lubricant rheology, oil transport mechanism and operating conditions. Therefore, this review is devoted to summarize the synthesis of main technical aspects, research efforts, conclusions and challenges that must be highlighted regarding piston skirt/liner lubrication and piston dynamics and slap.

Research on the lubrication performance of engine piston skirt–cylinder liner frictional pair considering lubricating oil transport

2018 ◽  
Vol 21 (4) ◽  
pp. 713-722 ◽  
Author(s):  
Jun Sun ◽  
Feifei Hao ◽  
Guangsheng Liu ◽  
Hu Wang ◽  
Qin Teng ◽  
...  
Keyword(s):  
Cylinder Liner ◽  
Lubricating Oil ◽  
Frictional Pair ◽  
Operating Cycle ◽  
Piston Skirt ◽  
Oil Transport ◽  
Bottom Dead Center ◽  
Lubrication Performance ◽  
Oil Flow ◽  
Secondary Motion

In current lubrication analysis of piston skirt, the flooded status is generally considered in the piston skirt–cylinder liner frictional pair in all strokes of an engine operating cycle. However, the quantity of lubricating oil at the entrance of piston skirt cannot always ensure the sufficient lubrication status of piston skirt–cylinder liner frictional pair when the piston moves from the bottom dead center to the top dead center in actual engine. In this article, based on the model of piston secondary motion, fluid lubrication, and lubricating oil flow, the lubrication performance of piston skirt–cylinder liner frictional pair is analyzed, in which the quantity of lubricating oil detained on the surface of cylinder liner after the piston skirt moves from the top dead center to the bottom dead center and is considered as the quantity of lubricating oil at entrance of piston skirt when the piston moves from the bottom dead center to the top dead center. The results show that compared with current analysis, in which the sufficient lubrication of piston skirt–cylinder liner frictional pair is assumed in all strokes of engine, there are remarkable changes for the lubrication performance of piston skirt–cylinder liner frictional pair and the piston secondary motion when the lubrication status of the frictional pair in the upstroke of piston is determined by considering actual lubricating oil transport in the lubrication analysis of piston skirt.

Front steering design guidelines formulation for e-scooters considering the influence of sitting and standing riders on self-stability and safety performance

2021 ◽  
pp. 095440702199217
Author(s):  
Milan Paudel ◽  
Fook Fah Yap
Keyword(s):  
Preventive Measures ◽  
Recent Trend ◽  
Dynamic Performance ◽  
Design Guidelines ◽  
Safety Performance ◽  
Design Parameters ◽  
Single Track ◽  
Standing Posture ◽  
Last Mile ◽  
Current Design

E-scooters are a recent trend and are viewed as a sustainable solution to ease the first and last mile problem in modern transportation. However, an alarming rate of accidents, injuries, and fatalities have caused a significant setback for e-scooters. Many preventive measures and legislation have been put on the e-scooters, but the number of accidents and injuries has not reduced considerably. In this paper, the current design approach of e-scooters has been analyzed, and the most common range of design parameters have been identified. Thereafter, validated mathematical models have been used to quantify the performance of e-scooters and relate them with the safety aspects. Both standing and seated riders on e-scooters have been considered, and their influence on the dynamic performance has been analyzed and compared with the standard 26-in wheel reference safety bicycle. With more than 80% of the accidents and injuries occurring from falling or colliding with obstacles, this paper tries to correlate the dynamics of uncontrolled single-track vehicles with the safety performance of e-scooters. The self-stability, handling, and braking effect have been considered as major performance matrices. The analysis has shown that the current e-scooter designs are not as stable as the reference safety bicycle. Moreover, these e-scooters have been found unstable within the most common range of legislated riding velocity. The results corroborate with the general perception that the current designs of e-scooters are less stable, easy to lose control, twitchy, or wobbly to ride. Furthermore, the standing posture of the rider on the e-scooter has been found dangerous while braking to avoid any disturbances such as potholes or obstacles. Finally, the front steering design guidelines have been proposed to help modify the current design of e-scooters to improve the dynamic performance, hence the safety of the e-scooter riders and the surroundings.

Theoretical Investigation of a Peristaltic Magneto-Fluid Dynamic Induction Compressor-2

1965 ◽  
Vol 9 (02) ◽  
pp. 56-65
Author(s):  
Joseph L. Neuringer ◽  
Eugene Migotsky ◽  
James H. Turner ◽  
Robert M. Haag
Keyword(s):  
Scaling Laws ◽  
Electromechanical Coupling ◽  
Constant Pressure ◽  
Fluid Dynamic ◽  
Pressure Rise ◽  
Magnetic Reynolds Number ◽  
Design Parameters ◽  
Propulsion Systems ◽  
Geometric Scaling ◽  
Axial Mass

In Part 3, the nature of the electromechanically induced motions inside the compressor both of the fluid conductor and of the pumped fluid when the electromechanical coupling is weak, i.e., in the limit of small magnetic Reynolds number, is investigated. The analysis predicts the development of a constant pressure gradient in the pumped fluid when the condition is imposed that the time-average axial mass flow across the conducting fluid annulus is zero. In Part 4, a preliminary feasibility study is made to determine whether the induction compressor has the potential to provide the pressure rise required to propel large and small undersea craft by means of jet propulsion systems for reasonable power and current-sheet inputs. Also determined here are the geometric scaling laws for the appropriate operating and design parameters.

Aerodynamic Similarity Principles and Scaling Laws for Windmilling Fans

2018 ◽  
Author(s):  
Dilip Prasad
Keyword(s):  
Rotational Speed ◽  
Pressure Loss ◽  
Scaling Laws ◽  
Dynamic Pressure ◽  
Stagnation Pressure ◽  
Design Parameters ◽  
Similarity Parameter ◽  
Wide Range ◽  
Simulation Results ◽  
Good Agreement

Windmilling requirements for aircraft engines often define propulsion and airframe design parameters. The present study is focused is on two key quantities of interest during windmill operation: fan rotational speed and stage losses. A model for the rotor exit flow is developed, that serves to bring out a similarity parameter for the fan rotational speed. Furthermore, the model shows that the spanwise flow profiles are independent of the throughflow, being determined solely by the configuration geometry. Interrogation of previous numerical simulations verifies the self-similar nature of the flow. The analysis also demonstrates that the vane inlet dynamic pressure is the appropriate scale for the stagnation pressure loss across the rotor and splitter. Examination of the simulation results for the stator reveals that the flow blockage resulting from the severely negative incidence that occurs at windmill remains constant across a wide range of mass flow rates. For a given throughflow rate, the velocity scale is then shown to be that associated with the unblocked vane exit area, leading naturally to the definition of a dynamic pressure scale for the stator stagnation pressure loss. The proposed scaling procedures for the component losses are applied to the flow configuration of Prasad and Lord (2010). Comparison of simulation results for the rotor-splitter and stator losses determined using these procedures indicates very good agreement. Analogous to the loss scaling, a procedure based on the fan speed similarity parameter is developed to determine the windmill rotational speed and is also found to be in good agreement with engine data. Thus, despite their simplicity, the methods developed here possess sufficient fidelity to be employed in design prediction models for aircraft propulsion systems.

Friction Reduction via Piston and Ring Design for an Advanced Natural-Gas Reciprocating Engine

2004 ◽  
Author(s):  
Grant Smedley ◽  
S. H. Mansouri ◽  
Tian Tian ◽  
Victor W. Wong
Keyword(s):  
Natural Gas ◽  
Internal Combustion Engines ◽  
Piston Ring ◽  
Substantial Reduction ◽  
Friction Reduction ◽  
Design Parameters ◽  
Design Strategies ◽  
Low Friction ◽  
Piston Skirt ◽  
Model Predictions

Friction from the power cylinder represents a significant contribution to the total mechanical losses in internal combustion engines. A reduction in piston ring friction would therefore result in higher efficiency, lower fuel consumption, and reduced emissions. In this study, models incorporating piston ring dynamics and piston secondary motion with elastic skirt deformation were applied to a Waukesha natural gas power generation engine to identify the main contributors to friction within the piston and ring pack system. Based on model predictions, specific areas for friction reduction were targeted and low-friction design strategies were devised. The most significant contributors to friction were identified as the top ring, the oil control ring, and the piston skirt. Model predictions indicated that the top ring friction could be reduced by implementing a skewed barrel profile design or an upward piston groove tilt design, and oil control ring friction could be reduced by decreasing ring tension. Piston design parameters such as skirt profile, piston-to-liner clearance, and piston surface characteristics were found to have significant potential for the reduction of piston skirt friction. Designs were also developed to mitigate any adverse effects that were predicted to occur as a result of implementation of the low-friction design strategies. Specifically, an increase in wear was predicted to occur with the upward piston groove tilt design, which was eliminated by the introduction of a positive static twist on the top ring. The increase in oil consumption resulting form the reduction in the oil control ring tension was mitigated by the introduction of a negative static twist on the second ring. Overall, the low-friction design strategies were predicted to have potential to reduce piston ring friction by 35% and piston friction by up to 50%. This would translate to an improvement in brake thermal efficiency of up to 2%, which would result in a significant improvement in fuel economy and a substantial reduction in emissions over the life of the engine.

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