Jozef Dlugoš

Innovative Model of Radial Fluid Bearing for Simulations of Turbocharger Rotordynamics

The paper describes the principles of an innovative computational model of slide bearing for effective and fast simulations of turbocharger rotordynamics. Theoretical background based on a numerical solution of the Reynolds equation is introduced. The developed simulation tool uses multibody software extended by user-written subroutines and specialized programs developed by authors. The capabilities of the innovative computational models and sample results are demonstrated on a middle size turbocharger rotor supported by fully floating ring bearings.

Contact Area Evaluation Experiment Verified by Computational Model in MBS

This article focuses on the experimental contact area evaluation. Test rig is designed in order to investigate the piston/cylinder liner contact. The conducted experiment is based on the principle of electrical contact resistivity between two tested machinery parts. The measured results are compared with different contact model theories. The computational simulation uses precomputed database of contact pressure and contact area depending on separation distance of surfaces. This simulation is solved by Multibody System (MBS) enhanced by the user-written FORTRAN subroutine. The results of experiment and simulations are discussed.

Computer Simulation of the Behavior of the Piston Ring Pack of Internal Combustion Engines

The continuously tightening regulations limiting the amount of exhaust gas components of internal combustion engines force the manufacturers to further increase the effectivity of their power units. Due to the already relatively highly-developed state of engines result in the need of research and development of even smaller engine parts – e.g. piston rings. The main aim of this project was to develop a tool for the computer simulation of the behavior of the piston ring pack, which could aid the optimization process of the piston ring pack towards lowered friction losses.

Advanced Computational Analysis of Connecting Rod of an Aircraft Engine

Development of internal combustion engine’s components is based on the use of advanced computational models in order to compare and verify the individual design proposals. Connecting rod, which performs a general planar motion, is exposed to the gas pressure forces, inertia, contacts, and hydrodynamic pressure during the engine operation cycle. To incorporate all these aspects, Finite Element Method (FEM) is extended by Finite Difference Method (FDM) simulating a slide bearing of connecting rod’s end. It includes different properties of lubricating oil (pressure and temperature dependent viscosity and density) and elastic deformations, so the pressure distribution in an oil film can be evaluated. The computational process concludes with an estimation of the endurance safety factor of the connecting rod. The four-cylinder inverted aircraft engine is used as an example.

The Influence of Rotor Unbalance on Turbocharger Rotor Dynamics

Shrnutí Članek analyzuje vliv nevyvahy na dynamiku rotoru turbodmychadla. Je zde prezentovan 3D vypočtovy model rotoru turbodmychadla a hydrodynamicky model kluzne ložiska. Sestaveni vysledneho vypočtoveho modelu na urovni virtualniho prototypu je provedeno v prostředi software pro řešeni dynamiky těles. Članek prezentuje vybrane vysledky, na kterych je podrobně rozebran vliv velikosti nevyvahy na dynamiku rotoru turbodmychadla. Abstract This paper describes the influence of an unbalance on turbocharger rotor dynamics. The structural model of the turbocharger rotor and the hydrodynamic model of the journal floating ring bearing are described and assembled in multibody dynamics software. Moreover, the paper presents various results describing rotor dynamics where the influence of an unbalance is discussed.

Role Of Computational Simulations In The Design Of Piston Rings

Abstract The paper presents computational approaches using modern strategies for a dynamic piston ring solution as a fluid structural problem. Computational model outputs can be used to understand design parameter influences on defined results of a primarily integral character. Piston ring dynamics incorporates mixed lubrication conditions, the influence of surface roughness on oil film lubrication, the influence of ring movement on gas dynamics, oil film formulation on a cylinder liner and other significant influences. The solution results are presented for several parameters of SI engine piston rings.

Computational Modelling of Piston Ring Dynamics in 3D

Shrnutí Pokročilé výpočtové modely pístní skupiny na základě virtuálních prototypů vyžadují mimo jiné i detailní popis dynamického chování pístního kroužku. Z tohoto hlediska je zřejmé, že pístní kroužky pracují v podmínkách, které obecně nelze zjednodušit na často využívaný osově symetrický model. Píst a vložka válce nemají dokonale kruhový tvar především v důsledku výrobních tolerancí a vnějšího tepelně-mechanického zatížení. V případech, kdy kroužek nedokáže kopírovat deformace vložky, nastane lokální ztráta kontaktu a následně i zvýšený profuk spalin a spotřeba oleje. V současné době využívané výpočtové modely nejsou schopné zahrnout všechny podstatné efekty. Článek se zaměřuje na tvorbu 3D poddajného modelu pístního kroužku s využitím Timoshenkovy teorie prutů a Multibody systému (MBS). Vytvořený výpočetní model je porovnán s numerickým řešením na základě metody konečných prvků (FEM). Abstract Advanced computational models of a piston assembly based on the level of virtual prototypes require a detailed description of piston ring behaviour. Considering these requirements, the piston rings operate in regimes that cannot, in general, be simplified into an axisymmetric model. The piston and the cylinder liner do not have a perfect round shape, mainly due to machining tolerances and external thermo-mechanical loads. If the ring cannot follow the liner deformations, a local loss of contact occurs resulting in blow-by and increased consumption of lubricant oil in the engine. Current computational models are unable to implement such effects. The paper focuses on the development of a flexible 3D piston ring model based on the Timoshenko beam theory using the multibody system (MBS). The MBS model is compared to the finite element method (FEM) solution.