Csaba Tóth-Nagy

14065556000

Publications - 12

Experimental Investigation on the Erosion Resistance Characteristics of Compressor Impeller Coatings to Water Droplet Impact

Csaba Tóth-Nagy István Barabás I. Zsoldos Pavel Novotny Richárd Takács Izolda Popa-Müller Balázs Dobos Miklós Zsolt Tabakov Norbert Kiss

Publication Name: Coatings

Publication Date: 2025-07-01

Volume: 15

Issue: 7

Page Range: Unknown

Description:

This study presents a comparative analysis of the water droplet erosion resistance of three compressor wheels coated with Ni-P and Si-P layers. The tests were conducted using a custom-developed experimental apparatus in accordance with the ASTM G73-10 standard. The degree of erosion was monitored through continuous precision mass measurements, and structural changes on the surfaces of both the base materials and the coatings were examined using a Zeiss Crossbeam 350 scanning electron microscope (SEM). Hardness values were determined using a Vickers KB 30 hardness tester, while the chemical composition was analysed using a WAS Foundry Master optical emission spectrometer. Significant differences in erosion resistance were observed among the various compressor wheels, which can be attributed to differences in coating hardness values, as well as to the detachment of the Ni-P layer from the base material under continuous erosion. In all cases, water droplet erosion led to a reduction in the isentropic efficiency of the compressor—measured using a hot gas turbocharger testbench—with the extent of efficiency loss depending upon the type of coating applied. Although blade protection technologies for turbocharger compressor impellers used in the automotive industry have been the subject of only a limited number of studies, modern technologies, such as the application of certain alternative fuels and exhaust gas recirculation, have increased water droplet formation, thereby accelerating the erosion rate of the impeller. The aim of this study is to evaluate the resistance of three different coating layers to water droplet erosion through standardized tests conducted using a custom-designed experimental apparatus.

Open Access: Yes

DOI: 10.3390/coatings15070767

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

Study of the Negative Work Area in the p-V Diagram of an HCCI Engine †

Csaba Tóth-Nagy

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

Homogeneously charged compression ignition is a promising combustion process that is proven to increase combustion efficiency and decrease exhaust emissions when compared to Otto or Diesel engine efficiencies and emissions. The HCCI process can be considered an advancement on the path to sustainability. However, improper control of the start of combustion causes the efficiency of the engine to drop significantly. The reason for this efficiency drop is that an early start of combustion causes the piston on the upward stroke to experience increased cylinder pressure after the combustion process is complete. The piston must further compress the cylinder content until it reaches the top dead center. During this process, the piston still experiences an increased gas force on the way towards TDC, having to invest extra disadvantageous work into the compression stroke, causing a negative work area in the pressure–volume diagram of the engine. The present study introduces the negative work area in the p-V diagram of an HCCI engine. It describes the phenomenon and explores the reasons behind it. It also investigates some of the factors affecting the negative work area in the p-V diagram.

Open Access: Yes

DOI: 10.3390/engproc2024079022

Automated Assessment of Engine Performance During Dynamometer Testing †

Csaba Tóth-Nagy Tamás Koller

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

The ever-increasing number of novel functions in modern vehicles continuously expands with the application of cognitive information technology, creating a new need for testing during market introduction. As the virtual test environment evolves, the need for real tests conducted on the road continuously decreases, saving time and cost while maximizing quality indicators. This article presents a new type of automatic monitoring system created in a fully virtual test environment. The automated assessment during dynamometer testing (ADT) method automatically evaluates the values measured on the engine dynamometer at predefined intervals, compares them to reference data, and provides feedback on the correctness of the current test. The present paper discusses the monitoring methodology and its application on an engine dynamometer, and it presents the results of the method applied during a real engine test.

Open Access: Yes

DOI: 10.3390/engproc2024079028

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 the Friction Modifying Effects of Graphene and C60 Fullerene Used as Nanoadditives in Engine Lubricating Oil Performed on an Oscillating Tribometer

Csaba Tóth-Nagy I. Szabó

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2023-01-01

Volume: 51

Issue: 3

Page Range: 257-262

Description:

The present article presents the results of tribological investigations performed on an off-the-shelf engine lubricant containing nanoadditives of multilayered graphene and C60 fullerene alternately. As anthropogenic CO2 is believed to be highly responsible for global climate change, its emission is regulated in many countries. CO2 emissions can be significantly decreased by improving the efficiency i.e. decreasing the losses in an engine. Hence reducing frictional losses was the ultimate scope of the investigations presented in this article. The experiments were carried out on an oscillating tribometer at the Department of Internal Combustion Engines at Széchenyi István University. The experiments showed that multilayered graphene in engine lubricant did not modify the friction coefficient inevitably (-1% to +4%). Fullerene nanoparticles, however, reduced the friction by 4–8%. The optimal fullerene doping quantity that resulted in the lowest friction showed to be at around 0.14 wt%.

Open Access: Yes

DOI: 10.3311/PPtr.20594

Timing Chain Wear Investigation Methods – Review

Csaba Tóth-Nagy Jan Rohde-Brandenburger L. Paulovics

Publication Name: Fme Transactions

Publication Date: 2022-01-01

Volume: 50

Issue: 3

Page Range: 461-472

Description:

Several methods are used for investigating timing chain wear, from fired engine dynamometer tests through tribological model tests to simulations. Research over the past decade has shown that component or tribometer tests can replace expensive engine dynamometer tests in many cases. Simulation methods can further reduce the cost and time of development. Simulation models require experimentally defined input parameters; therefore, experiment-based methods cannot be completely avoided. However, a comprehensive comparison or validation of the various experimental and simulation techniques is difficult, as the literature on the topic is relatively scarce. This study aims to give a systematic comparison of the results of several investigation methods of timing chain wear, supported by data measured at Széchenyi István University, such as fired engine dynamometer tests, cold dynamometer tests, component tests, and tribometer tests, presenting their benefits and limitations, where possible through examples and results. The study also provides an insight into the compatibility of different measurement methods.

Open Access: Yes

DOI: 10.5937/fme2203461P

Experimental Investigation of the Friction Modifying Effects of Different Nanoforms of Graphene Additives in Engine Lubricating Oil

Csaba Tóth-Nagy I. Szabó

Publication Name: Fme Transactions

Publication Date: 2022-01-01

Volume: 50

Issue: 2

Page Range: 248-259

Description:

This article presents the results of an experimental investigation of different nanoforms of graphene used as a nano additive in engine lubricating oil. The experiments were carried out on a pin-on-disc tribometer at the Department of Internal Combustion Engines and Propulsions at Széchenyi István University. The paper introduces the experimental equipment and the experimental method and presents the research findings. The paper concludes that fullerene can decrease friction by 7% on average when used as a nano additive in engine lubricating oil. Furthermore, fullerene did not present a sedimentation problem when used as an additive up to 0.25 wt% in lubricant instead of graphene and multiwalled carbon nanotubes. The paper attempts to explain the friction decreasing effect and the possible roles of carbon nano additives in tribological systems.

Open Access: Yes

DOI: 10.5937/fme2201248T

Development of comparative investigation method for timing chain wear analysis using oscillating tribometer

Csaba Tóth-Nagy Rajmund Kuti Jan Rohde-Brandenburger L. Paulovics

Publication Name: Acta Technica Jaurinensis

Publication Date: 2021-11-24

Volume: 14

Issue: 4

Page Range: 406-423

Description:

This paper presents the development of a test procedure to investigate timing chain components under abrasive stress on a tribometer. Engine developers use cost and time expensive engine dynamometer tests to investigate timing chain life expectancy under different conditions. Tribometer tests are fast and cost effective, but these use standardized specimen material and geometry that greatly differ from the original tribological system of the timing chain. Manufacturing specimens from the original chain material using the original technology is complicated; surface quality and hardness properties cannot be guaranteed. The aim of research was to develop a test method for rapid and cost-effective comparison of engine lubricants, timing chain materials or coatings, as well as to assess the wear resistance of the chain to contaminants. Various uncontaminated and carbon black blended lubricants were compared using standard-based ball-on-disc tribometer tests to tribometer tests using actual timing chain components (bush-on-pin test) of a Diesel engine. Lubricants were ranked in terms of coefficient of friction and wear. Results showed that bush-on-pin tests were comparably suitable for testing lubricants when evaluated against standard ball-on-disc tribometer tests.

Open Access: Yes

DOI: 10.14513/actatechjaur.00620

Compression ignition linear engine design variable effects

Csaba Tóth-Nagy Parviz Farmouri Nigel N. Clark

Publication Name: American Society of Mechanical Engineers Internal Combustion Engine Division Publication ICE

Publication Date: 2011-12-01

Volume: Unknown

Issue: Unknown

Page Range: 1029-1036

Description:

A linear engine/alternator was simulated and designed, and a prototype was built at West Virginia University. This paper describes the engine and presents original operational data. The linear engine was a two-cylinder, two-stroke, common rail direct injection, compression ignition engine. The engine was built using off the shelf components to reduce cost where it was possible. Engine control, injection duration and timing, were achieved using a microcontroller with piston position as a control input. Experiments on the engine were performed to study its behavior. The studied variables included mass of the translator, amount of fuel injected, injection timing, load, and stroke with operating frequency and mechanical efficiency as the basis of comparison. At this point of development, the engine was far from optimized; however, the trends in engine behavior were clear. Increasing the translator mass resulted in decreased operating frequency. Increasing the stroke length also resulted in decreased operating frequency. Overcharging and increased fueling rate, both, resulted in increased power output, efficiency, and operating frequency. Advancing injection timing resulted in increased frequency, efficiency and power output, and decreased stalling frequency. This suggests that the engine operated in an HCCI-like fashion. © 2011 by ASME.

Open Access: Yes

DOI: 10.1115/ICEF2011-60157