Modeling the Effects of Piston Skirt Distortion on the Design of Pistons for Optimum Lubrication in a Reciprocating Engine PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Modeling the Effects of Piston Skirt Distortion on the Design of Pistons for Optimum Lubrication in a Reciprocating Engine PDF full book. Access full book title Modeling the Effects of Piston Skirt Distortion on the Design of Pistons for Optimum Lubrication in a Reciprocating Engine by William Lawrence Blair. Download full books in PDF and EPUB format.
Author: William Lawrence Blair
Publisher:
ISBN:
Category :
Languages : en
Pages : 196
Get Book Here
Book Description
Author: William Lawrence Blair
Publisher:
ISBN:
Category :
Languages : en
Pages : 196
Get Book Here
Book Description
Author: William L. Blair
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Author: Luke Frank Moughon
Publisher:
ISBN:
Category :
Languages : en
Pages : 129
Get Book Here
Book Description
(Cont.) Moreover, increasing oil supply (i.e., increasing effective oil film thickness) tends to decrease net friction by promoting hydrodynamic lubrication. Changes to piston geometry were shown to have significant effects on friction. In order to maximize hydrodynamic support, the pressure must be distributed evenly across the piston skirt; this can be achieved by making the skirt-liner clearance as even and smooth as possible. The model confirmed that skirt profiles with gentle slopes tend to reduce net friction, as do skirt ovality values that closely approximate the shape of the liner. Moreover, the grooves machined into the skirt surface were shown to have a deleterious effect on friction if their amplitude was large relative to the thickness of the oil film. Using relatively small-amplitude grooves facilitates oil movement and retention without leading to direct contact with the liner. After piston geometry has been optimized to promote hydrodynamic lubrication, further refinements, such as reducing oil viscosity, are possible.
Author:
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 306
Get Book Here
Book Description
Author: Dongfang Bai (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 147
Get Book Here
Book Description
Ever-increasing demand for reduction of the undesirable emissions from the internal combustion engines propels broader effort in auto industry to design more fuel efficient engines. One of the major focuses is the reduction of engine mechanical losses, to which the friction of the piston skirt is one important contributor. Yet there lacks a sufficient understanding of the skirt lubrication behavior to effectively optimize the piston skirt system in practice. The ultimate goal of this work is to develop a comprehensive model to advance the predictability of the skirt friction while integrating all the dynamic behavior of the piston secondary motion and the structural deformation of the piston skirt and cylinder liner. Major contributions of this work are analysis of and development of a model for the oil transport and exchange of the piston skirt region and its surroundings. The new oil transport model is composed with two elements. First, the oil scraped into the chamfer region by the oil control ring during a down-stroke is tracked and its accumulation and release to the skirt region are modeled. Second, oil separation and re-attachment are allowed in the skirt region, breaking conventional full-attachment assumption in lubrication studies. The new oil transport model together with hydrodynamic and boundary lubrication model were coupled with piston secondary motion and structural deformation of the piston skirt and cylinder liner. For numerical efficiency and physics clarity, we used different discretization for the lubrication from the structural deformation. The final model is robust and efficient. The discussion of the model results is focused mainly on the oil transport. There exist a general pattern in available oil for skirt lubrication, namely, skirt tends to be starved when it travels at the upper portion of a stroke. Comparison with visualization experiment for oil accumulation patterns show consistency between model prediction and observation. This work represents a major step forward to realistically predicting skirt friction and the influence of all the relevant design and operational parameters. However, oil supply to the region below the piston skirt can largely influence the outcome of the friction prediction and its mechanism is system dependent. Additionally, simple treatment of the oil transport in the current model is merely a first step to modeling the complex fluid problems involved. Improvements of this model based on application and further analysis will make it a more powerful engineering tool to optimize the skirt system to minimize its undesirable outputs.
Author: Pasquale Pio Totaro
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
Get Book Here
Book Description
The interest in reducing emission and improving engine efficiency has become a major push in industry, due to upcoming stricter regulations. A great deal of attention has been given to the frictional losses due to piston and liner interaction, as they represent a significant portion of the total mechanical losses. This thesis work focuses on further development and application of an existing model for the piston's secondary motion and skirt lubrication. Model development has been focused on introducing liner dynamic deformation, temperature and shear-thinning effect on viscosity, and arbitrary skirt's shape definition. The theory behind the inclusion of these components is discussed and the modifications to the existing model are explained. In regards to the model's applications, an important topic is the model validation, for which friction results from simulations are compared with experimental results obtained on a floating liner engine. The analysis covers the running condition of 1000 rpm, at partial and full load. This study is, however, not concluded and more cases need to be studied in order to complete the validation of the model. The second application focuses on the effects of geometrical patterns on the skirt on friction and secondary motion of the piston. First, some regular patterns were studied and found to have negative effects on friction due to their inability to build sufficient hydrodynamic pressure, compared to the baseline design. Then, a different sets of patterns were proposed to more effectively utilize available oil and to maximize the hydrodynamic pressure generation in the skirt region. The results show that new strategy can significantly reduce friction of the skirt without introducing negative impact on the secondary motion. This thesis work aims to make the model a more complete and powerful tool to understand piston's secondary motion and the applications are meant to show the capabilities of the model, as an instrument to approach piston's design and inspire new ways and ideas to reduce frictional losses.
Author: Fiona McClure
Publisher:
ISBN:
Category :
Languages : en
Pages : 241
Get Book Here
Book Description
Internal combustion engines dominate transportation of people and goods, contributing significantly to air pollution, and requiring large amounts of fossil fuels. With increasing public concern about the environment and the reliability of oil supplies, automotive companies are pushed to improve engine design in order to reduce engine emissions and fuel consumption. This project aims to develop a numerical model of piston dynamics and lubrication in internal combustion engines, enabling prediction of friction generation at the piston -cylinder bore interface, and oil transport in the power cylinder system. It is currently estimated that the piston - cylinder bore friction accounts for up to 25% of the power loss in a typical engine, while oil transported to the combustion chamber by the piston and ring-pack contributes significantly to engine emissions. A dry piston model was first developed to allow fast calculation of approximate piston dynamics. An elastohydrodynamic lubrication model was then developed to allow direct numerical simulation of the effect of piston tooling marks, and comparison with results obtained using an Average Reynolds equation with flow factors. The lubrication model was incorporated into the piston dynamics model, enabling more accurate evaluation of friction and oil transport. Comparison between the dry and lubricated model results demonstrate the effect of oil film thickness on piston lateral motion, tilt, friction generation and oil transport.
Author: Mubashir Gulzar
Publisher: LAP Lambert Academic Publishing
ISBN: 9783845478043
Category :
Languages : en
Pages : 128
Get Book Here
Book Description
The book focuses the rough piston skirts and liner surfaces and to incorporate these aspects in two dimensional hydrodynamic and elastohydrodynamic lubrication (EHL) of piston skirts in the initial engine start-up. This research work considers the deterministic roughness asperity with the average flow factor method.The randomly generated surface with deterministic asperity is modelled for piston skirt EHL. For this developed model, parametric studies on the salient features like the engine start-up speed, hydrodynamic load, radial clearance, and viscosity of lubricant, is undertaken.
Author: Huijie Xu
Publisher:
ISBN:
Category : Internal combustion engines
Languages : en
Pages :
Get Book Here
Book Description
Author: Andreas Petrou Panayi
Publisher:
ISBN:
Category : Pistons
Languages : en
Pages : 390
Get Book Here
Book Description
