Unsteady Thrust Force Loading of a Turbocharger Rotor During Engine Operation

2015 ◽  
Author(s):  
Bernhardt Lüddecke ◽  
Philipp Nitschke ◽  
Michael Dietrich ◽  
Dietmar Filsinger ◽  
Michael Bargende
Keyword(s):  
Thrust Bearing ◽  
Thrust Force ◽  
Combustion Engine ◽  
Operating Conditions ◽  
Turbine Stage ◽  
Force Modeling ◽  
Thrust Load ◽  
Bearing System ◽  
Engine Cycle ◽  
Bearing Friction

The bearing system of a turbocharger has to keep the rotor in the specified position and thus has to withstand the rotor forces that result from turbocharger operation. Hence, its components need to be designed in consideration of the bearing loads that have to be expected. The applied bearing system design also has significant influence on the overall efficiency of the turbocharger and impacts the performance of the combustion engine. It has to ideally fulfil the trade-off between bearing friction and load capacity. For example, the achievable engine’s low end-torque is reduced, if the bearing system produces more friction losses than inherently unavoidable for safe and durable operation because a higher portion of available turbine power needs to be employed to compensate bearing losses instead of providing boost pressure. Moreover, also transient turbocharger rotor speed up can be compromised and hence the response of the turbocharged combustion engine to a load step becomes less performant than it could be. Besides the radial bearings, the thrust bearing is a component that needs certain attention. It can already contribute to approx. 30 percent of the overall bearing friction, even if no load is applied and this portion further increases under thrust load. It has to withstand the net thrust load of the rotor under all operating conditions resulting from the superimposed aerodynamic forces that the compressor and the turbine wheel produce. A challenge for the determination of the thrust forces appearing on engine is the non-steady loading under pulsating conditions. The thrust force will alternate with the pulse frequency over an engine cycle what is caused by both the engine exhaust gas pressure pulses on the turbine stage and — to a smaller amount — the non-steady compressor operation due to the reciprocating operation of the cylinders. The conducted experimental investigations on the axial rotor motion as well as the thrust force alternations under on-engine conditions employ a specially prepared compressor lock nut in combination with an eddy current sensor. The second derivative of this signal can be used to estimate the occurring thrust force changes. Moreover, a modified thrust bearing — equipped with strain gauges — was used to cross check the results from position measurement and thrust force modeling. All experimental results are compared with an analytical thrust force model that relies on the simultaneously measured, crank angle resolved pressure signals before and after the compressor and turbine stage. The results give insight into the axial turbocharger rotor oscillations occurring during an engine cycle for several engine operating points. Furthermore, they allow a judgment of the accuracy of thrust force modeling approaches that are based on measured pressures.

Unsteady Thrust Force Loading of a Turbocharger Rotor During Engine Operation

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Bernhardt Lüddecke ◽  
Philipp Nitschke ◽  
Michael Dietrich ◽  
Dietmar Filsinger ◽  
Michael Bargende
Keyword(s):  
Thrust Bearing ◽  
Thrust Force ◽  
Combustion Engine ◽  
Operating Conditions ◽  
Turbine Stage ◽  
Force Modeling ◽  
Thrust Load ◽  
Bearing System ◽  
Engine Cycle ◽  
Bearing Friction

The bearing system of a turbocharger has to keep the rotor in the specified position and thus has to withstand the rotor forces that result from turbocharger operation. Hence, its components need to be designed in consideration of the bearing loads that have to be expected. The applied bearing system design also has significant influence on the overall efficiency of the turbocharger and impacts the performance of the combustion engine. It has to ideally fulfill the trade-off between bearing friction and load capacity. For example, the achievable engine’s low end-torque is reduced, if the bearing system produces more friction losses than inherently unavoidable for safe and durable operation because a higher portion of available turbine power needs to be employed to compensate bearing losses instead of providing boost pressure. Moreover, also transient turbocharger rotor speed up can be compromised and hence the response of the turbocharged combustion engine to a load step becomes less performant than it could be. Besides the radial bearings, the thrust bearing is a component that needs certain attention. It can already contribute to approximately 30% of the overall bearing friction, even if no load is applied and this portion further increases under thrust load. It has to withstand the net thrust load of the rotor under all operating conditions resulting from the superimposed aerodynamic forces that the compressor and the turbine wheel produce. A challenge for the determination of the thrust forces appearing on engine is the nonsteady loading under pulsating conditions. The thrust force will alternate with the pulse frequency over an engine cycle, which is caused by both the engine exhaust gas pressure pulses on the turbine stage and—to a smaller amount—the nonsteady compressor operation due to the reciprocating operation of the cylinders. The conducted experimental investigations on the axial rotor motion as well as the thrust force alternations under on-engine conditions employ a specially prepared compressor lock nut in combination with an eddy-current sensor. The second derivative of this signal can be used to estimate the occurring thrust force changes. Moreover, a modified thrust bearing—equipped with strain gauges—was used to cross check the results from position measurement and thrust force modeling. All experimental results are compared with an analytical thrust force model that relies on the simultaneously measured, crank angle resolved pressure signals before and after the compressor and turbine stage. The results give insight into the axial turbocharger rotor oscillations occurring during an engine cycle for several engine operating points. Furthermore, they allow a judgment of the accuracy of thrust force modeling approaches that are based on measured pressures.

Analysis of Thrust Bearing Impact on Friction Losses in Automotive Turbochargers

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Bjoern Hoepke ◽  
Tolga Uhlmann ◽  
Stefan Pischinger ◽  
Bernhardt Lueddecke ◽  
Dietmar Filsinger
Keyword(s):  
Test Bench ◽  
Thrust Bearing ◽  
Journal Bearing ◽  
Special Test ◽  
Friction Power ◽  
Overall Efficiency ◽  
Center Section ◽  
Thrust Load ◽  
Bearing System ◽  
Bearing Friction

The importance of automotive turbocharger performance is continuously increasing. However, further gains in efficiency are becoming progressively difficult to achieve. The bearing friction losses impact the overall efficiency of the turbocharger and accordingly the understanding of bearing systems and their characteristics is essential for future improvements. In this work, a detailed analysis on the mechanical losses occurring in the bearing system of automotive turbochargers is presented. Friction losses have been measured experimentally on a special test bench up to rotational speeds of nTC = 130,000 1/min. Special interest was given to the thrust bearing characteristics and its contribution to the total friction losses. For this, the experiments were split into three parts: first, friction power was determined as a function of turbocharger speed at zero externally applied thrust load. Second, external thrust load up to 40 N was applied onto the turbocharger bearing at fixed rotational speeds of nTC = 40,000, 80,000, and 120,000 1/min. Increasing thrust load was observed to result in increasing friction losses amounting to a maximum of 32%. At last, a specially prepared turbocharger center section with deactivated thrust bearing was investigated. A comparison of these results with the measurement of the conventional bearing system under thrust-free conditions allowed separating journal and thrust bearing losses. The contribution of the thrust bearing to the overall bearing losses appeared to be as high as 38%. Furthermore, a modeling approach for estimating the friction power of both fully floating journal bearing as well as thrust bearing is illustrated. This theoretical model is shown to predict friction losses reasonably well compared to the experimental results.

Active axial vibration control of a shaft-bearing system excited by the dynamic thrust force

2022 ◽  
pp. 147509022110702
Author(s):  
Mingke Ren ◽  
Xiling Xie ◽  
Dequan Yang ◽  
Zhiyi Zhang
Keyword(s):  
Active Control ◽  
Adaptive Algorithm ◽  
Thrust Bearing ◽  
Thrust Force ◽  
Moving Average ◽  
Arma Model ◽  
Experimental System ◽  
Axial Vibration ◽  
Control Approach ◽  
Bearing System

The axial vibration of a shaft-bearing system induced by the thrust excitation is usually composed of multiple tones. To suppress the axial vibration of the shaft-bearing system, two inertial electro-magnetic actuators are mounted symmetrically at the thrust bearing and work in parallel to exert control forces. The control signal is generated by an adaptive algorithm with subband filtering, which aims to attenuate over a broadband the vibration of the thrust bearing and its foundation induced by the dynamic thrust force. To reduce computational complexity, the recursive computation is partly realized with the auto-regressive moving average (ARMA) model. The proposed active control approach is evaluated numerically at first with the dynamic model of the shaft-bearing system and then verified with an experimental system. It is demonstrated by the numerical and experimental results that the active control approach is able to suppress the multi-tone vibration of the thrust bearing and the foundation. Moreover, in comparison to the single-band adaptive feedback algorithm, the adaptive algorithm with subband filtering is more effective when the disturbance contains multiple tones.

Development of Full Scale Reactor Coolant Pump Thrust Bearing Test System and Qualification Process for Retrofit Thrust Bearing Oil Seal With Commercial Grade Components

2008 ◽  
Author(s):  
Jason Sinkhorn ◽  
William Mendez
Keyword(s):  
Design Of Experiments ◽  
Thrust Bearing ◽  
Test System ◽  
Full Scale ◽  
Operating Conditions ◽  
Coolant Pump ◽  
Reactor Coolant ◽  
Operating Variables ◽  
Computer Controlled ◽  
Thrust Load

A fleet of reactor coolant pump thrust bearings were experiencing loss of oil inventory through a face rubbing mechanical oil seal. In a span of six months, Westinghouse developed a replacement seal which retrofit into the existing bearing, erected a full scale bearing test system, operated the prototype seal through various operating conditions utilizing Six Sigma Design of Experiments methodology, qualified the seal for sustained use in an operating reactor plant and supported the installation of the retrofit seals. The retrofit seal replaced a problematic face rubbing seal with a controlled leakage design utilizing a floating ring — a pressure reducing bushing free to translate in the X-Y plane. The prototype seal system was optimized through use of the Design of Experiments. Design optimization was aimed at reducing oil aeration to levels lower than those present with the original equipment, which when achieved, provided improved heat transfer from the bearing. The test system was constructed around a production thrust bearing, identical to those installed in the plant, which was modified to facilitate collection of a variety of process variables. In all, the system was capable of simultaneously sampling and storing data from 56 separate channels; while recording digital video from eight sources, from cameras both inside and outside of the bearing. All in-service operating parameters were duplicated by the test system, including: computer controlled variable vertical thrust load from zero to 90 tons, computer controlled variable radial thrust load and acceleration from standstill to operating speed in 16 seconds. Safe shutdown operating variables were monitored automatically by the system, in the event of a faulted condition the system automatically detected the fault and initiated a safe shutdown automatically. To date, all installed seal systems have performed as designed; allowing essentially no leakage at this location from the bearing reservoir. The test system continues to be used on development projects focused on improving other aspects of the bearing’s performance.

Applications of vibro-acoustic measurement and analysis in conjunction with tribological parameters to assess surface fatigue wear developed in the roller-bearing system

2021 ◽  
pp. 135065012098246
Author(s):  
Shashikant Pandey ◽  
Muniyappa Amarnath
Keyword(s):  
Roller Bearing ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Stribeck Curve ◽  
Fatigue Wear ◽  
Surface Fatigue ◽  
Rolling Element ◽  
Measurement And Analysis ◽  
Contact Surfaces ◽  
Bearing System

Rolling-element bearings are the most commonly used components in all rotating machinery. The variations in the operating conditions such as an increase in the number of operating cycles, load, speed, service temperature, and lubricant degradation result in the development of various defects such as pitting, spalling, scuffing, scoring, etc. The defects that appeared on rolling contact surfaces cause surface deterioration and change in the vibration and sound levels of the bearing system. The present experimental investigations are aimed at assessing the surface fatigue wear that appears on the contact surfaces of roller bearings. The studies considered the estimation of specific film thickness, analysis of surface fatigue wear developed on the rolling-element surfaces, surface roughness analysis, grease degradation analysis using Fourier transform infrared radiation, and vibration and sound signal measurement and analysis. The results obtained from the experimental investigation provide a good correlation between surface wear, vibration, and sound signals with a transition in the lubrication regimes in the Stribeck curve.

scholarly journals Analysis of the Total Unit Energy Consumption of a Car with a Hybrid Drive System in Real Operating Conditions

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3966
Author(s):  
Jarosław Mamala ◽  
Michał Śmieja ◽  
Krzysztof Prażnowski
Keyword(s):  
Energy Consumption ◽  
Internal Combustion Engine ◽  
Electric Drive ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Hybrid Drive ◽  
Total Unit ◽  
Unit Energy ◽  
Unit Energy Consumption

The market demand for vehicles with reduced energy consumption, as well as increasingly stringent standards limiting CO2 emissions, are the focus of a large number of research works undertaken in the analysis of the energy consumption of cars in real operating conditions. Taking into account the growing share of hybrid drive units on the automotive market, the aim of the article is to analyse the total unit energy consumption of a car operating in real road conditions, equipped with an advanced hybrid drive system of the PHEV (plug-in hybrid electric vehicles) type. In this paper, special attention has been paid to the total unit energy consumption of a car resulting from the cooperation of the two independent power units, internal combustion and electric. The results obtained for the individual drive units were presented in the form of a new unit index of the car, which allows us to compare the consumption of energy obtained from fuel with the use of electricity supported from the car’s batteries, during journeys in real road conditions. The presented research results indicate a several-fold increase in the total unit energy consumption of a car powered by an internal combustion engine compared to an electric car. The values of the total unit energy consumption of the car in real road conditions for the internal combustion drive are within the range 1.25–2.95 (J/(kg · m)) in relation to the electric drive 0.27–1.1 (J/(kg · m)) in terms of instantaneous values. In terms of average values, the appropriate values for only the combustion engine are 1.54 (J/(kg · m)) and for the electric drive only are 0.45 (J/(kg · m)) which results in the internal combustion engine values being 3.4 times higher than the electric values. It is the combustion of fuel that causes the greatest increase in energy supplied from the drive unit to the car’s propulsion system in the TTW (tank to wheels) system. At the same time this component is responsible for energy losses and CO2 emissions to the environment. The results were analysed to identify the differences between the actual life cycle energy consumption of the hybrid powertrain and the WLTP (Worldwide Harmonized Light-Duty Test Procedure) homologation cycle.

Numerical Analysis of a Coupled Porous Journal and Thrust Bearing System

2005 ◽  
Vol 127 (1) ◽  
pp. 120-129 ◽  
Author(s):  
Takuji Kobayashi ◽  
Hiroshi Yabe
Keyword(s):  
Thrust Bearing ◽  
Dynamic Performance ◽  
Internal Flow ◽  
Disk Drive ◽  
Rotating Shaft ◽  
Static And Dynamic Characteristics ◽  
Bottom Face ◽  
Magnetic Hard Disk ◽  
Bearing System ◽  
Porous Sleeve

A numerical model has been developed to analyze both static and dynamic characteristics of a coupled porous journal and thrust bearing system that is used to support a rotating shaft in a magnetic hard disk drive. The analyzed system is composed of a porous sleeve, a herringbone-grooved solid thrust plate and a flanged shaft, where the bottom end is closed to form a cantilever spindle. The inner surface and the bottom face of the porous sleeve operate as a herringbone-grooved journal and thrust bearing, respectively. The model is based on the narrow groove theory for the bearing oil film, and Darcy’s law for the internal flow in the porous sleeve. The pressure distribution, static equilibrium position of the shaft and dynamic coefficients are obtained under a given external axial load. There exists a window of permeability of the porous sleeve that presents significant advantage to prevent the creation of a sub-ambient condition and to maintain a large thrust bearing film thickness at the expense of some loss of dynamic performance.

An Accurate Solution of the Gas Lubricated, Flat Sector Thrust Bearing

1977 ◽  
Vol 99 (1) ◽  
pp. 82-88 ◽  
Author(s):  
I. Etsion ◽  
D. P. Fleming
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Thickness Distribution ◽  
Maximum Load ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Thrust Bearings ◽  
Practical Design ◽  
Minimum Film Thickness

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Characterization of a Piezoelectric Membrane for MEMS Power

2001 ◽  
Author(s):  
K. Bruce ◽  
R. Richards ◽  
D. Bahr ◽  
C. Richards
Keyword(s):  
Thin Film ◽  
Power System ◽  
Combustion Engine ◽  
Thermal Power ◽  
Operating Conditions ◽  
Mechanical Power ◽  
Central Component ◽  
Carnot Cycle ◽  
Modular Architecture ◽  
Micro Power

Abstract Work toward the development of a thin-film piezoelectric membrane generator is presented. The membrane generator is the central component of a new MEMS power generation system, the P3 micro power system. The P3 micro power system is based on a two-dimensional, modular architecture, in which the individual generic modules or unit cells each have all the functions of an engine integrated. Each unit cell is an external combustion engine, in which thermal power is converted to mechanical power through the use of a novel thermodynamic cycle that approaches the ideal vapor Carnot cycle. Mechanical power is converted into electrical power through the use of a thin-film piezoelectric membrane generator. This paper introduces the concept of the thin-film piezoelectric membrane generator, and describes its design and fabrication. Results of a study to characterize the performance of the piezoelectric membrane generator under expected operating conditions are presented. Current prototypes of the membrane generator are shown to be capable of producing a peak power of 0.1 milliWatts at a voltage of 0.5 Volts.

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