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Interdependence of torsional vibration damper parameters on crankshaft's torsional vibrations

Mitianiec W., Buczek K.

Journal of KONES

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2008

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Vol. 15, No. 4

351-358

EN

Torsional vibration of crankshaft is a harmful phenomenon in every type of engine. It can easily cause a fatigue failure in engines with relatively long crankshafts and big bore diameters (usually above 90 mm). For these types of engines, the resonance caused by specific low order harmonic of gas force and inertia force of oscillating masses occurs in engine speed range, thus resonant torsional moment of big amplitude is generated. This moment, additionally acting on crankshaft, is harmful and can easily cause its fatigue failure. In order to reduce the resonance effects, the torsional vibration damper (TVD) has to be used. That is the reason why application of torsional vibration dampers is almost a rule in these types of engines. The viscose TVD is the most popular type of vibration damper in heavy duty diesel engine. Moment of inertia of its plunger is the main criterion of damper selection. It is the basic factor, which determines the amount of dissipation work, decreasing the additional torsional moment caused by resonance. Increasing plunger's moment of inertia induce the rise of dissipation work but simultaneously decrease natural frequencies of a crank train, what allows to resonate with low order harmonic of tangential force acting on crankpin. The paper concerns an analysis of influence of viscose TVD parameters on crankshaft's torsional vibration for six cylinder inline heavy duty diesel engine.

2

Formation of fuel mixture in a SI two-stroke engine with direct fuel injection

Mitianiec W., Forma M.

Journal of KONES

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2008

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Vol. 15, No. 2

329-337

EN

Decreasing of fuel consumption and high hydrocarbon emission in a SI two-stroke engine applied in motorcycles, scooters and small power units is possible by change of fuelling system on direct fuel injection. The main problem of mixture formation is short time for fuel evaporation after injection which should begin after closing of the exhaust port. However well interaction between the scavenge air and fuel jet from the injector located in the cylinder head can induce the small size of fuel droplets and fast evaporation. The paper presents the computational results of fuel mixture formation and combustion process in direct fuel injection two-stroke engine Robin EC-12 with capacity 115 cm3. The simulation was carried out by use KIVA code with assumption of initial parameters from the experiment of the carbureted engine. Earlier fuel injection influences on better evaporation and mixture formation with small stratification, which enables full mixture combustion. The paper shows phases of mixture formation, combustion and concentration of the combustion product in the cylinder. Spray guided high pressure direct injection system in SI two-stroke engine enables fulfill the restrictions of gas emission of one-wheeler vehicles and small power units. New modern two-stroke engines and environmental protection require new fuelling systems and one of the most promising methods is direct spray guided fuel injection. Many work were done in this subject, however still there is no better option for small power two-stroke engines.

3

Torsional vibration analysis of crankshaft in heavy duty six cylinder inline engine

Mitianiec W., Buczek K.

Czasopismo Techniczne. Mechanika

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2008

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R. 105, z. 8-M

193-207

EN

The paper contains torsional vibration analysis of crankshaft in six cylinder inline heavy duty engine taking advantage of the crank train reduction to multi-mass model. Obtained results were compared with FEM analysis performed in ANSYS to determine the influence of the reduction a physical continuum to multi-mass model. In order to achieve the course of torsional moment in the highly load cross section of the crankshaft, there was a necessity to use Fourier analysis of tangential force acting on crank and execute the analysis of most beneficial firing order.

PL

Artykuł zawiera analizę drgań skrętnych sześciocylindrowego rzędowego silnika trakcyjnego, przeprowadzoną za pomocą redukcji układu korbowego do wielomasowego modelu. Otrzymane wyniki porównano z wynikami analizy MES wykonanej w programie ANSYS, umożliwiając określenie wpływu redukcji układu ciągłego do modelu wielomasowego. W celu otrzymania przebiegu momentu skręcającego w najsilniej obciążonym przekroju poprzecznym wału konieczne było przeprowadzenie analizy Fouriera siły stycznej działającej na wykorbienie wału oraz analizy najkorzystniejszej kolejności zapłonów.

4

Mixture formation at spray guided direct injection in SI two-stroke engine

Mitianiec W., Forma M.

Czasopismo Techniczne. Mechanika

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2008

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R. 105, z. 7-M

115-127

EN

In the paper the top direct injection on the mixture formation is considered. Modelling of physics process during injection was carried out with assumption of the exact future experimental set-up. The hemisphere combustion chamber causes additional motion of gas and fuel before ignition. A difference approximation of differential equations of the injection and combustion was used for solving the problem by KIVA program. Velocity of gas influences on the distribution of liquid and vapour phases of injected fuel. In the paper: distribution of gaseous phase of fuel, gas temperature, vectors of charge velocity and vapour mass ratio for top and side fuel injection systems were shown.

PL

W artykule rozważano proces bezpośredniego wtrysku paliwa. Modelownie procesu fizycznego wtrysku paliwa zostało przeprowadzone przy założeniu przyszłego badawczego silnika. Półkulista komora spalania powoduje dodatkowy ruch gazu i paliwa przed zapłonem. Do rozwiązania tego problemu przeprowadzono aproksymację różnicową równań różniczkowych procesu wtrysku i spalania za pomocą programu KIVA. Prędkość gazu wpływa na rozprzestrzenianie się fazy ciekłej i parowej wtryskiwanego paliwa. W artykule pokazano rozkład par paliwa, temperaturę gazu, wektory prędkości ładunku i udział masowy par paliwa przy głowicowym i bocznym wtrysku paliwa.