Márk Pesthy

57219992322

Publications - 6

Experimental Analysis of a Turbocharger: Influence of Oil Supply Temperature and Pressure on the Bifurcation Phenomenon in Subsynchronous Frequencies

Csaba Tóth-Nagy Márk Pesthy Máté Boros

Publication Name: Lubricants

Publication Date: 2025-03-01

Volume: 13

Issue: 3

Page Range: Unknown

Description:

This study presents an experimental analysis of a turbocharger equipped with a semi-floating bearing system, with a particular focus on the bifurcation phenomenon within the subsynchronous vibration spectrum. A predefined design of experiments (DoE) methodology was employed to determine the measurement domains to be analyzed, where the primary input parameters included the lubricant supply temperature and pressure values. The bifurcation phenomenon in relation to the physical parameters of the system is observed via vibration and displacement sensors in two directions, enabling the collection of subsynchronous frequency data for further insights into the influence of lubricant parameters on the rotor system. While the nonlinear effect of oil temperature is well studied in the literature. However, the combined effect of oil supply temperature and pressure was not yet examined, which was the focus of the present study. This paper aims to investigate its coupled effects on the bifurcation phenomenon associated with both lubricant temperature and pressure. The occurrence of the introduced phenomenon is further examined to enhance the understanding of the uncharted behavior of turbocharger rotors and other rotor-bearing-based machinery.

Open Access: Yes

DOI: 10.3390/lubricants13030133

Experimental Analysis on the Hysteresis Phenomenon in the Range of Subsynchronous Frequency as a Function of Oil Temperature with Regard to Turbochargers

Csaba Tóth-Nagy Gusztáv Fekete Márk Pesthy Máté Boros

Publication Name: Lubricants

Publication Date: 2025-02-01

Volume: 13

Issue: 2

Page Range: Unknown

Description:

This study presents an experimental analysis of a turbocharger with semi-floating ring bearings, focusing on hysteresis in subsynchronous vibrations. Four automotive oils (SAE 0W-20, SAE 0W-30, SAE 5W-30, SAE 5W-40) were tested across six oil inlet temperatures from 20 °C to 120 °C during ramp-up and ramp-down cycles to examine the effects of lubricant viscosity and temperature on rotor dynamics. Hysteresis and bifurcation points were observed at distinct rotational speeds in both directions, with subsynchronous components providing insights into rotor–lubrication interactions. This study applies the concept of hysteresis loop width for turbocharger rotors, highlighting its nonlinear dependence on oil temperature, an unexpected and unexplained phenomenon. Additionally, the results suggest that vibration sensors could provide real-time feedback on oil supply conditions, offering potential enhancements for turbochargers and other rotating machinery.

Open Access: Yes

DOI: 10.3390/lubricants13020060

Parameter-Driven Campbell Diagram Variations in Turbocharger Rotors: A Rotordynamic Simulation Study Using ROSS †

Csaba Tóth-Nagy Márk Pesthy Máté Boros

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

This study investigates the influence of rotor design parameters on the Campbell diagrams of automotive turbocharger rotors using rotordynamic simulations. A finite element model of the rotor is developed within the Python-based ROSS package, incorporating key parameters such as disk mass, lubricant viscosity, and bearing positioning. Employing this model, simulations are conducted to generate Campbell diagrams across a range of operational speeds. The analysis focuses on how variations in these parameters affect the critical speeds and corresponding vibration modes identified in the Campbell diagrams. The results provide valuable insights into the rotordynamic behavior of automotive turbochargers and their sensitivity to design choices. This information can be utilized to optimize rotor design for improved stability, reduced noise generation, and enhanced overall performance.

Open Access: Yes

DOI: 10.3390/engproc2024079058

Vibroacoustic Investigation of Automotive Turbochargers Focusing on the Effect of Lubricant Temperature and Bearing Conditions

Csaba Tóth-Nagy Márk Pesthy Jan Rohde-Brandenburger Richárd Takács

Publication Name: Lecture Notes in Mechanical Engineering

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 861-870

Description:

The detailed mapping of the rotordynamic properties of a turbocharger is an important tool of turbocharger development, where one of the main focuses is lubricant condition. This is well understandable considering the trend of decreasing viscosity levels of engine lubricants. This article introduces rotordynamic investigations of turbochargers performed on a component testbench. The experiments were carried out with different inlet oil temperatures. The goal was to investigate the effect of oil temperature on rotordynamic properties. The component under investigation was a turbocharger of a 4-cylinder gasoline engine equipped with full-floating hydrodynamic bearings. The application of journal bearings can cause several rotordynamic phenomena at high rotational speeds that are typical of turbochargers. Experiments were conducted on new condition and used conditions (over 50.000 km, in urban traffic) of a turbocharger, where oil temperature varied between 20 ℃ and 120 ℃ in six steps. Lubricant temperature and bearing wear had a noticeable influence on both the synchronous and subsynchronous vibrational behaviour of the turbocharger. The present paper describes the applied testing processes and evaluation methods. Results contributed to ongoing comprehensive research regarding rotordynamic mapping of automotive turbochargers.

Open Access: Yes

DOI: 10.1007/978-3-031-15211-5_71

Experimental Investigation of Vibroacoustic Behaviour of an Automotive Turbocharger with Semi-floating Bearing

Balázs Rácz Péter Sass Márk Pesthy Jan Rohde-Brandenburger

Publication Name: Lecture Notes in Mechanical Engineering

Publication Date: 2021-01-01

Volume: 22

Issue: Unknown

Page Range: 245-255

Description:

Due to the strict European emission standards and the constant aspiration for the higher power density, turbochargers became essential components of the modern internal combustion engines. Turbochargers are high-speed operating machines thus the design of the rotor and the bearing system requires special attention. The motions of the rotor are affected by several parameters, such as bearing design, clearances, structure of the surface and also the quality and the physical properties of the used lubricant. If the motions of the rotor are intensive in a wide rotational speed range, the bearing load increases, resulting in a reduced lifespan. The motion of the rotor induces vibrations, which leads to audible noise emission to the environment. In this article, the vibrations of a four-cylinder spark ignition engine’s turbocharger are presented, based on component test-bench experiments. Furthermore, the main vibration components and their influencing factors are briefly introduced. During the experiments, the noise and vibrations of the turbocharger have been measured with different viscosity grade oils from 20 °C to 140 °C inlet temperature. The results showed that the amplitudes of both the synchronous and subsynchronous vibrations changed significantly and the volumetric flow is highly dependent on the temperature. The effect of the changing oil temperature will be analyzed with an emphasis on the subsynchronous vibrations and the possible cause of the phenomenon will be presented. Finding the optimal parameters with the lowest possible vibration response could result in an extended lifetime and provides important information for the balancing process during production.

Open Access: Yes

DOI: 10.1007/978-981-15-9529-5_21

Aerodynamic Effect of Shallow Circumferential Grooves in the Shroud of a Centrifugal Compressor

Pavel Novotny Márk Pesthy Jiří Vacula Richárd Takács Johan Prinsier

Publication Name: Journal of Turbomachinery

Publication Date: 2026-01-01

Volume: 148

Issue: 1

Page Range: Unknown

Description:

The standard aerodynamic design of a centrifugal compressor features an unshrouded impeller with a smooth shroud. However, the shape of the shroud significantly influences the final compressor parameters. Previous research has shown that even small geometric changes in the shroud, referred to as casing treatment, can substantially affect the operating characteristics of a rotating machine. This article presents a novel casing treatment for a centrifugal compressor, involving the creation of ten circumferential grooves with a semi-circular profile in a meridional section. The radius of these grooves is approximately equal to the tip clearance. Experimental results demonstrate that the presence of these grooves shifts the surge line toward lower flowrates, increases efficiency in a narrow region between the best efficiency point and the surge line and shifts the choke line toward lower flowrates. External sound pressure measurements indicate a reduction in amplitudes at sub-synchronous frequencies, suggesting a potential link between the compressor map's influence and the suppression of aerodynamic instabilities. Computational fluid dynamics analysis supports the experimental observations, revealing a significant influence of energy dissipation caused by the applied grooves. This study highlights the considerable impact of shroud geometry on centrifugal compressors with unshrouded impellers and offers valuable insights for further research into casing treatments.

Open Access: Yes

DOI: 10.1115/1.4069422