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1

The change of friction and load-carrying capacity of the journal bearing with the consideration of the oil ageing

Sikora G., Miszczak A.

Tribologia

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2016

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nr 5

171--181

EN

This paper presents numerical calculations of the hydrodynamic pressure distribution, carrying capacity, and friction coefficient in the gap of a journal bearing. The analysed bearing is lubricated using motor oil. In this paper, oil ageing and temperature influence on viscosity are taken into account. Viscosity changes in the pressure and shear rate are not considered. These changes will be considered in other papers. For the hydrodynamic lubrication analysis, laminar flow of the lubrication fluid and non-isothermal lubrication model of the journal bearing were assumed. As the constitutive equation, the classical, Newtonian model was used. This model was extended by the viscosity changes in temperature and exploitation time. For the considerations, the cylindrical journal bearing with the finite length and smooth bearing, with the full angle of wrap were taken.

PL

W niniejszej pracy przedstawiono obliczenia numeryczne rozkładu ciśnienia hydrodynamicznego, siły nośnej oraz współczynnika tarcia w szczelinie poprzecznego łożyska ślizgowego smarowanego olejem silnikowym z uwzględnieniem zmian lepkość oleju od temperatury i czasu eksploatacji. W pracy nie uwzględniano zmian lepkości od ciśnienia i szybkości ścinania. Takie zmiany będą uwzględnione w innych pracach. Do analizy hydrodynamicznego smarowania przyjęto laminarny przepływ cieczy smarującej oraz nieizotermiczny model smarowania łożyska ślizgowego. Jako równanie konstytutywne zastosowano klasyczny model newtonowski z uwzględnieniem zmian lepkości od temperatury i czasu eksploatacji. Do rozważań przyjęto walcowe łożysko ślizgowe o skończonej długości z gładką panewką o pełnym kącie opasania.

2

Równania hydrodynamicznego smarowania poprzecznych łożysk ślizgowych z uwzględnieniem starzenia się oleju

Sikora G., Miszczak A.

Logistyka

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2015

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nr 4

5649--5656, CD2

PL

Celem niniejszej pracy jest przedstawienie równań podstawowych hydrodynamicznej teorii smarowania w których uwzględniona będzie zmiana lepkości oleju smarującego od ciśnienia, temperatury, prędkości ścinania i czasu eksploatacji. Do analizy hydrodynamicznego smarowania przyjęto laminarny przepływ cieczy smarującej oraz nieizotermiczny model smarowania łożyska ślizgowego. Przyjęto walcowe łożysko ślizgowe o skończonej długości z gładką panewką o pełnym kącie opasania. W pracy przedstawiono równania podstawowe: równanie pędu, równanie ciągłości strugi, równanie zachowania energii we współrzędnych walcowych. Do rozważań przyjęto czynnik smarujący o nienewtonowskich właściwościach. Zmiany lepkości z czasem eksploatacji zamodelowano funkcją wykładniczą na podstawie wyników badań eksperymentalnych. Zaproponowano również przyjęcie modelu Corssa zmian lepkości dynamicznej w funkcji szybkości ścinania.

EN

The purpose of this paper is to present the basic equations of the hydrodynamic lubrication theory. Change of the oil viscosity in this equations depends on pressure, temperature, shear rate and exploitation time. Assumptions for the hydrodynamic lubrication analysis are laminar flow of the lubrication fluid and nonisothermal lubrication model. Considerations apply cylindrical journal bearing of finite length with a smooth bushing and full wrap angle. This paper presents the basic equations: momentum conservation equation, continuity equation, conservation of energy equation in cylindrical coordinates system. For the consideration, the non-Newtonian lubrication fluid was assumed. Dependence of the dynamic viscosity on the exploitation time was modeled by the exponential function based on the results of experimental studies. There was also cross model proposed to describe changes in dynamic viscosity in the changes of shear rate.

3

Determination of the material coefficients of the selected lubrication oils including ageing process

Sikora G., Miszczak A.

Logistyka

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2015

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nr 4

5641--5648, CD2

EN

Oil viscosity is a parameter influenced by many factors. Most of those factors are very well described in the literature. Such a factor is for example influence of the temperature or pressure on the oil’s viscosity. But there are also some parameters, which due to its complexity, are not described sufficiently. Such a parameter is influence of oil ageing on viscosity changes and pseudo-viscosity coefficients for the non-newtonian oils. Authors of this paper considered to determinate this parameters. Examined oil was Shell Helix AV-L, according to SAE 5W40, exploited in the personal car VW TOURAN, equipped with 2.0 L, turbocharged diesel motor. Examination of the viscosity changes in the function of shear rate, were performed on the Haake Mars III rheometer, using high shear rate chamber. Conditions of this examination were temperature of 40°C and shear rates between 0 and 73000 s-1. For the determination of pseudo-viscosity coefficients, combined analytical and experimental method, proposed by K. Wierzcholski [13] was used.

PL

Lepkość oleju smarowego jest parametrem na który wpływa wiele czynników. Dość powszechnie znany i zbadany został wpływ temperatury i ciśnienia na zmianę lepkości. Są jednak również parametry które, przede wszystkim ze względu na swoją złożoność, są opisane w sposób niewystarczający. Takim parametrem jest wpływ czasu eksploatacji na zmianę lepkości i współczynników pseudolepkości dla olejów o właściwościach nienewtonowskich. Wyznaczeniem tychże parametrów zajęli się autorzy w niniejszej pracy. Do badań wykorzystano olej silnikowy Shell Helix AVP SAE 5W40 użytkowany w silniku 2000cm3 TDI samochodu osobowego VW TURAN. Badania zmian lepkości w funkcji prędkości deformacji przeprowadzono na reometrze Hakke Mars III przy wykorzystaniu komory wysokiego ścinania. Badanie wykonano przy 40°C i prędkości ścinania zmieniającej się od 0 doj 73000 s-1. Do wyznaczenia współczynników pseudolepkości wykorzystano metodę analityczno-doświadczalną zaproponowaną przez K. Wierzcholskiego [13].

4

The influence of oil’s exploitation time on load carrying capacity in a slider bearing

Sikora G., Miszczak A.

Journal of KONES

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2015

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Vol. 22, No. 3

207--212

EN

In this paper, authors are presenting conclusions of the numerical calculations of pressure distribution and capacity in a slider bearing with taking changes of oil viscosity in exploitation time into account. Changes of the engine oil’s viscosity, which depend on the exploitation time, were determined on Haake Mars III rheometer and the conclusions were published in Solid State Phenomena and Logistyka in 2015. Numerical calculations were performed by solving of Reynolds equation, using finite difference method and own calculation procedures in Mathcad 15. Reynolds equation was developed by solving the continuity equation and the momentum conservation equation from the fundamentals. For the considerations, the laminar and stationary lubricating of the slider bearing of finite length and full angle of wrap were taken. Assumption of the stationary flow concerns lack of changes in flow parameters in short period of considered phenomena, f. ex. in one hour. Smooth and non-porous bushing were assumed. The aim of this paper was preliminary estimation of influence of viscosity changes in the exploitation time on the load carrying capacities of the cross slider bearing. Wherefore, the viscosity changes dependence on the pressure, temperature and also shear rate, were not taken into account. The basic equations were developed to the non-dimensional form and estimated according to the thin layer theory. In the calculations, the Reynolds boundary conditions concerning pressure distribution were taken into account. Preliminary calculations were performed for different models of viscosity changes in time and circumstances, where the viscosity increases and decreases in exploitation time.

5

The studies on lubricity and contamination analysis of the personal car’s lubricating oil with taking oil ageing into account

Sikora G.

Journal of KONES

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2013

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Vol. 20, No. 3

375--379

EN

In this paper, the results of researches on lubricity and content analysis of the personal car’s engine oil are presented. The measurements of lubricity are made on the T02-U four-ball tester. The content analysis is made on the Spectroil Q100 spectrometer, which makes it available to measure the amount of 24 chemical elements. Due to this analysis, technical condition of the engine is possible to estimate. Tested oil is Shell Helix AV-L, which was exploited in the personal car, Volkswagen Touran, equipped with the turbo charged diesel engine, with the capacity of 2.0 litres. The samples for oil ageing characteristics were taken from the engine in the intervals approx. 3500 km. This research was performed as a result of the other studies on the dynamic viscosity characteristics. In the viscosity researches for this oil, was shown, that in the first period of the exploitation time, the viscosity decreases significantly. Detailed research on the additives and wear products content, as well as a lubricity characteristic, defines the reason of such a significant decrease of the oil properties. This paper is a part of a wider research on the oil ageing characteristics. It will support development to the new mathematical model of the lubricating oil viscosity changes during the exploitation time of the engine

6

Studies on dynamic viscosity changes of the engine’s lubrication oil depending on the pressure

Sikora G.

Journal of KONES

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2013

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Vol. 20, No. 4

405--409

EN

This paper is a part of the wider author’s research on the development of the new mathematical model for description of the viscosity changes of the lubrication oil in the exploitation time. Pressure of the oil is a variable parameter in the combustion engine and depends on many design parameters such as oil pump efficiency, geometry of the channels and lubricated element. It depends also on the exploitation parameters, such as rotational speed of the engine or contamination degree of the oil filter. So big amount of the factors, which have an influence on the pressure, resulted in the decision to examine, how big influence has a pressure in the oil viscosity. For the researches, the oil samples from the different combustion engines, both petrol and diesel, with different capacities, were taken into account. In each case, for the examination were taken samples both for the fresh oil and used oil from the change. Results of this research are shown in the tabular in correlation to the engines specification. In the next researches, after collecting all the oil ageing data, author will examine the pressure distribution in the slide bearing. After that it will be will possible to estimate the importance of the pressure changes for the proper work of the engine.

7

The analysis of changes in total base number and the flash point in the exploited engine oil

Sikora G., Miller H.

Journal of KONES

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2012

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Vol. 19, No. 3

395-398

EN

This paper is a continuation of the analysis of the grade of wear of the engine oil, used in the Caterpillar's marine engine, which is working in the engine's room of the harbour tug. Previous studies were related to the dynamic viscosity, lubricity and the grade of the metallic elements contamination. In these studies, the viscosity of the oil in most samples decreased with time of exploitation. However, in some samples, an increase of the viscosity was observed, what may indicate the fuel entering into the circulation of lubricating oil and its subsequent evaporation. Aim of this study is to determine the size of the Total Base Number changes and the flash point changes. The authors examine the changes in Total Base Number and the flash point of the exploited engine oil, in specified intervals in time between its exchanges. The results are analyzed and compared to the previously obtained results of the viscosity, lubricity and the grade of the metallic elements contamination. The analyses of the Total Base Number were conducted on the RST 822 Radiometer from Radiometer Analytical A/S, according to the polish standard PN-76/C-04163: Petroleum Products. Determination of the Total Base Number by potentiometric titration with perchloric acid. Flash point was determined using the Cleveland, in the open pot, using an ISL FP 92 5G device from Tusnovics Instruments Poland Ltd. The conclusions of this paper lead to better understanding of the processes, which occur in marine engines and its influence on the oil aging. Understanding of this process contributes significantly to a more accurate mathematical modelling of the aging process of engine oil.

8

Oil aging influence on the slide journal bearing lubrication

Miszczak A., Sikora G.

Journal of KONES

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2010

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Vol. 17, No. 2

327-333

EN

In this study authors solve the fundamental set of equations of the hydrodynamic theory of lubrication, namely are: the continuity equation, conservation of momentum and conservation of energy for the case of stationary slide bearings lubrication with a thixotropic lubricant. Adoption of assumption of steady flow loads in the considered phenomenon to the changes absence of the flow parameters in a short time period i.e. in one hour. In the constitutive equation is assumed that the stress tensor is a function of strain tensor, dynamic viscosity of oil and hydrodynamic pressure. Dynamic viscosity decreases in a long period of time of workf. ex. after 10 000 by 20 000 kilometres. In a thin layer of oil film, density and thermal conductivity was assumed to be constant. Authors define the lubricant's dynamic viscosity as a product of viscosity changes in temperature, pressure and time eta = eta(T).eta(p).eta(t). In the analysis of hydrodynamic lubrication, Authors consider a Journal bearing of finite length, with the smooth sleeve with a full circumferential angle. Fundamental equations are written in dimensionless form and estimated according to the theory of a thin boundary layer. Prepared in this way equations of motion can be solved by various methods. Authors propose to solve the motion equations with a method of small parameter. The small parameter method we define the unknown functions in a form of uniformly convergent power series expanded in the neighbourhood of the small parameters. In most used cases, absolute value of the small parameter is less than unity. These functions are substituted into simultaneous fundamental equations, then the series are multiplied using Cauchy's method. Comparing coefficients with the same exponents of small parameter, simultaneous set of differential equation is acquired, from which next approximations of unknown functions are appointed. With so obtained equations, the equation that allows assigning hydrodynamic pressure and hydrodynamic pressure corrections resulting from taking into account the impact of pressure, temperature and ageing in viscosity changes of the lubricant successively can be assigned.

9

Porównanie kinetyki termooksydacji mineralnych i syntetycznych olejów transformatorowych

Molenda J., Cichawa M.

Problemy Eksploatacji

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2007

|

nr 2

119-128

PL

W artykule porównano kinetykę terooksydacji mineralnych i syntetycznych olejów transformatorowych, zbadaną na podstawie wyników oznaczania liczby kwasowej oraz analizy widm IR. Obróbka matematyczna uzyskanych widm pozwoliła na wyodrębnienie nakładających się pasm spektralnych oraz obliczenie pola powierzchni pasma analitycznego, charakterystycznego dla produktów termooksydacji. Badania przeprowadzono dla laboratoryjnie terooksydowanych próbek oleju mineralnego (Nytro 10GBN) i estrowego (Midel 7131). Na podstawie przeprowadzonych badań stwierdzono, że kinetykę powstawania tlenoorganicznych produktów starzenia oleju mineralnego można opisać modelem liniowym, natomiast kinetykę powstawania związków karboksylowych w oleju estrowym modelem wielomianowym trzeciego stopnia.

EN

In this paper kinetics of thermal oxidation of mineral (Nytro 10GBN) and synthetic transformer oils (Midel 7131) were comparised. Research was based on results of acid number determination and analysis of IR spectrum. Mathematical describe of obtained spectrum allowed to separate overlapping spectral bands and calculate of analytical band's field, characteristic for thermal oxidation products. It has been found that the kinetics of oxygen-containing products formation can be described by linear model, and the kinetics of carboxylic compounds formation in oil can be described by polynominal model of third degree.

10

Badanie odporności na starzenie krajowych i zagranicznych olejów turbinowych metodą długotrwałego utleniania

Kania A.

Energetyka

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2000

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nr 5

214-217

PL

Przedstawiono metodę i wyniki badań odporności na starzenie olejów skandynawskich Statoil oraz krajowych Remiz i TU-32. Zastosowana metoda jest uznana w kraju i za granicą jako metoda badania kwalifikującego obowiązującego producentów.

EN

A method and tests results of resistance against ageing the Scandinavian Statoil iols as well as Remiz and TU-32 domestic oils have been presented. Utilised method is recognised in the country and abroad as a qualifying test method binding producers.