Computational Mechanics
and
Virtual Engineering
COMEC 2007
11 – 13 OCTOBER 2007, Brasov, Romania
Industrial application
CONCERNING the ACQUISITION simulation
Of experimental datA oF the flow process
FOR fresh and USED oils
Irina RADULESCU1, Alexandru RADULESCU2, Tom SAVU2
1SC ICTCM SA Bucharest, ROMANIA, e-mail:
2POLITEHNICA University from Bucharest, ROMANIA, e-mail: ,
Abstract:The paper describes the acquisition process simulation of experimental data which are obtained from the experimental rheological tests for three fresh and used lubricants types. The researches demonstrated that rheological models which characterized correctly the lubricants behaviour are:the newtonian fluid pattern and the power law pattern. There were obtained reference values for fresh and used oils, after experimental determinations, which are used in the experimental data acquisition simulation tests. For each lubricant type there were realized simulation tests for data experimental acquisition, by squeezing the oil between two circulars parallels surfaces, which near, one to another, with constant velocity. By adoption the geometry and the constant squeeze velocity and imposing the lubricant thickness variation – it was simulated the data acquisition process, using LabVIEW programming.
Keywords: acquisition process, simulation, experimental data, flow process, oils
1. INTRODUCTION
One of the actually problem of our modern economyis to stop the degradation of our earth ecosystem, generated by the continuous grow of waste and residues of the humans activities, which has a devastator ecological impact to the environment. Considering the problem referring to control the oil residue, there are many important directions to follow: avoiding the waste of lubricants and fuels, recuperating and reconditioning the lubricants, create new ecological fuels or biodegradable ones [1].
Analyzing new conditions of the actual manufacturing, our project team had developed a new method of fast diagnosis of liquid lubricants (used for cars, air ships, sea ships, engines and different systems). The start idea was to change the oil at the imposed moment, when the lubricant is practically complete used and not regarding the theoretical products recommendations. For the actual level of science and technology, the oil change method from a not complete used system is out-of-date, having great economical waste and applying ecologically effects[2].
At this moment, the oil from the installation is changed based on the recommendations of the oilcans made by the producers (number of hours in good repair or number of distance covered in kilometres). The determination of the changing moment for oil is different, because that depends of some factors that are difficult to control.
In some case, at cars, the oil is changed more frequently that is necessary; in order to be sure that its properties were not all vanished. This type of procedure is not dangerous, from theoretical point of view, but it is expensive.
For the change of used oil it cannot be establish a time of change available for all type of engines cars or for distance covered in a time interval. The degradation of lubricant oil, collected directly from „working” conditions depends on many factors, the most important being: the oxidation and impurity. The level of impurity and the period of used oil depend on the exploitation conditions, the quality of oil, the construction and the technical state of engine.
The research project proposes the achievement of a modeling and simulation instrument for the wear behaviour and durability and the development of a fast diagnose method for the liquid lubricants, with minimal investments and a high precision level, easy to use.
The project has a strong economical and ecological impact and it is according to the reglementations and corresponding standards requests at European and international level (quality, medium, risk). The proposed simulation LabVIEW instrument can be used by a large number of users, in the field of the research and didactical laboratories – and in the small production or exploitation enterprises.
This is a common way to a rapid and adaptive design according to the market demands. The conception and the utilisation of this virtual modelling and simulation instrument is equivalent to a production and delivery of customised goods (specific to the industrial domain necessities), with a high adaptability level to the customers demands.
2. The integrated informatic instrument
for the evaluation of the lubricants’ durability
The researches are about an the achievement of an industrial application concerning the acquisition process simulation of experimental data of the flow process for the industrial fresh and used oils, with the help of extrusion phenomena of oil film (squeeze-film), [3]. The methodology to estimate the wear degree of lubricants uses an original theory to calculate the distance in the direction of one norm in multivectorial spaces. It is very fast (under 30 seconds) and it uses for diagnosis a low quantity of oil (about 1 ml).
If the oil is used more than the normal, it could be an admonition of the owner of installation for troubleshoots which may appear; if the oil is less used, it could say how long will still be used.
By collecting and testing the sample of oil in different moments of time, respectively with different wear degrees, at the end we could draw the curve of viscometric wear for each type of oil.
In addition, using adequate mathematic equipment, we will establish “life reserve” of oil lubricant used. Collecting and comparative testing of oil samples at different moments of time, consequently with different levels of wear, we can design the wear curves particular for each type of lubricant (Figure 1).
Figure 1:Flow curves (viscosity versus shear rate) for testing fluids
We could adopt an objective criterion concerning the degradation of oil, who will establish the right moment to change it. The accuracy and the precision of the method are assured by the comparative character of all tests made, by using in parallel two systems of measurements: one in proper conception, original and like reference - a viscometric one.
The domain of analysis for the wear degree and durability lubricants are enrich by the achievement of one unitary informational ensemble, which contain modules of theoretical calculus and experimental ones, with big complexity.
The modeling and simulation instrument for the evaluation and quantification of wear degree and for the durability of lubricants is structured using LabVIEW software facilities, one of the most modern instruments of work for conditioning and data acquisition, elements that represent the new character and complexity.
2.1. Some aspects concerning the lubricant oil degradation
There are many factors implicated inlubricant oil degradation, but the most important are the oxidation and impurities, their level and the period of used oils depend on the exploitation conditions, quality, construction and technical state of engine.
For the appreciation of the stage of degradation in order to establish the moment of changing, there are made periodical physic-chemical analysis for the oil. It is considered downgrade when its characteristics had touched some limit value established for each type of engine. The primary parameters are: density, viscosity, contain of fuel, contain of water, color, point of flammability, ash, insoluble in pentane, insoluble in benzene, acidity and basicity of oil.In order to obtain quanticable and practical information concerning service lubricants there were tested 3 fresh and used oil types: ELF EXCELLIUM LDX 5W-40, ELF PERFORMANCE EXPERTY 10W-40, ELF COMPETITION ST 10W-40.
The experimental installation used to rheological tests consists ina rheometer RHEOLAB MC 1, with digital control of rotational speed (0.05-2000 rpm) and of the centrifugal moment (0.05-50 mNm), a thermostat bath with temperature regulation (-200C ÷ 1500C), anadjustable support and data acquisition computer (which is connected to the rheometer).
According DIN 54453 (Z1 – DIN) the geometry used for the determinations consists in a double gap cylinderCouette; the rheological test imposed for viscosity courves determination is Control Shear Stress (CSS), the friction effort is constant imposed (shear stress) (INPUT) and the deformation speed measurement (shear rate) (OUTPUT). According this test the friction effort is imposed by a linear rule, this values being [0.1÷60] Pa at going and [60÷0.1] Pa at returning. The viscosity values were measured in 100 points and for each point the measurement holded 5s. For each oil trial the viscosity tests were been at 4 temperatures: 50C, 200C, 400C, 600C.
Next figure (figure 2) presents the viscosity courves function the deformation speed, for the four temperatures (50C, 200C, 400C, 600C) – the example is for the trial ELF EXCELLIUM LDX 5W-40 (fresh – it is named NEW and also – 10000 km used, named OLD). The figure shows the difference between the Excellium_NEW test viscosity and the Excellium_OLD, in order to conclude that the wear decreases the viscosity.Similar were tested the other trials for ELF PERFORMANCE EXPERTY 10W-40 and for ELF COMPETITION ST 10W-40, having the same conclusions.
Figure 2: The viscosity curves for theExcellium_NEW trial and Excellium_OLD trial
2.2 The modeling and simulation instrument
The architecture of modeling and simulation instrument is the summary type, who has like base a program with a general frame, who manages an ensemble made by four modules: theoretical module, rheological testing module, viscometric validation module and spectrometric analysis module.
The modeling and simulation instrument for the evaluation and quantification wear degree and the durability of lubricants is structured set by facility of LabVIEW software, one of the most modern instruments of work from the tele-server, conditioning and acquisition of date, element that represent the new character and complexity.
As base for modeling and simulation instrument for evaluate and for the quantification the wear degree and durability of lubricants is the software LabVIEW - Laboratory Virtual Instrument Engineering Workbench – graphic background program developed by National Instruments Corporation. This program is useful in data acquisition, processing and presentation, to control and command industrial process, to analyze the dynamic behavior system.
The purpose is to achieve executable applications (virtual instruments), using a graphic language in this environment. The application has control elements and indicators for the friction couple diameter (1), for the extrusion speed (2), for the thickness of lubricant film (3), for the consistency indicator (4), for the lubricant type (5), for the utilization indications (6), for saving current data into a file (7), for stopping the operation (8), for graphical presentation of pressure variation (9), for the graphical presentation of the lifting power (10) and for the flow index specification (11)[4].
Figure 3: The modeling and simulation instrument
Experimental data acquisition simulation is an easy and friendly instrument, with high work speed. By using a graphical interface with many control elements and indicators – the research team respects all parameters which affect lubricant flow process, the input and output data – giving the opportunity to preserve information with a data saving procedure (figure 4) into a data saving .xls file (figure 5).
Figure 4: Data saving procedure
Figure 5: Data saving .xls file
3. CONCLUSION
Thisresearch concerning industrial application leads to a new, efficient, performed and ecological methodology. It gives results for evaluation and quantification of wear degree and lubricants durability. It is about a new complex device for diagnosis of “life reserve” for lubricants oils. The research creates a modern laboratory in order to develop new directionsin lubricants durability area.
The acquisition process simulation of experimental data of the flow process for the industrial fresh and used oils has a high level of parameters and offers good quality, having acomplete integrated system, which is open, flexible, scalable and it uses high informational technologies.
Another result of this project is thepartnership obtained, which assures the internal development of the institutions and organizations networks, which can become internal sources of scientifically and technical competence.
The research leads to the competitive development for the social and educational area, being capable to answer to strategically needs of long term development.
The researches are relevant for the design domain, which create modeling and simulating instruments, giving more information in wear process, specific for each lubricant, making evident factors with role of grow in life time. They are realized in order to find all possibilities to reduce environmental pollution, enriching the thematic area of long management of resources.
REFERENCES
[1]Alliston-Greiner A.F.: Test methods in tribology, Proc.1 st World Tribology Congress, London, 1997.
[2]*** The real costs of lubrication, /Archives/ Technical/2002/ CIMRealCost Paper.pdf
[3]Macosko Ch.W., Rheology; principles, measurements, and applications, VCH Publ., New York, 1994
[4]Arsenoiu L., Savu T., Szuder A.: Bazele programării în LabVIEW, Ed. Printech, Bucureşti, 1999.
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