Predictions of Rotordynamic Performance for Electric Turbocompound

2012 ◽  
Author(s):  
Keun Ryu ◽  
Augustine Cavagnaro
Keyword(s):  
High Speed ◽  
Fuel Efficiency ◽  
Element Model ◽  
Operating Conditions ◽  
System Level ◽  
Engine Oil ◽  
Storage Device ◽  
Prototype Development ◽  
Linear And Nonlinear ◽  
Type Motor

An electric turbocompound (ETC) system for heavy duty diesel engines offers significant system level benefits, such as improved fuel efficiency and reduced NOx emissions with a lower CO2 footprint. Presently, a high speed switched reluctance type motor/generator is integrated into a turbocharger shaft between the turbine and compressor wheels. The motor assists rapid acceleration of the turbocharger shaft, thereby rendering faster transient response. At steady or over-boost operating conditions, the generator provides electric power which can be used directly or stored in an on-board storage device. ETCs operate at high rotational speeds and, if equipped with fluid film bearings, use pressurized engine oil to lubricate the bearings (journal and thrust). This paper presents comprehensive predictions of the linear and nonlinear shaft motions of an ETC supported on floating ring bearings. A rotor structural finite element model integrates the floating ring bearing model for prediction of the rotor-bearing system (RBS) linear and nonlinear forced responses under actual operating conditions. Predictions show a complex rotordynamic behavior of the RBS with large amplitude subsynchronous motions over a wide speed range. However, the subsynchronous whirl motions reach a limit cycle enabling continuous operation without system failure. Most importantly, stiffness of the lamination stack mounted on the shaft has a significant effect on the amplitude and frequency content of the shaft motion. The present analysis effectively aids to accelerate ETC prototype development with increased reliability and product troubleshooting.

Demonstration of the Benefits of SAE 30 Stationary Gas Engine Oil in Full Scale Engine Tests

2021 ◽  
Author(s):  
Thijs Schasfoort ◽  
Zoe Fard ◽  
Torsten Gehrmann ◽  
Steffen Hollatz
Keyword(s):  
Positive Impact ◽  
Fuel Efficiency ◽  
Test Methods ◽  
Operating Conditions ◽  
Engine Oil ◽  
Gas Engine ◽  
Fuel Consumption Rate ◽  
Efficiency Performance ◽  
Endurance Testing ◽  
Efficiency Test

Abstract This paper evaluates the benefits of an SAE 30 monograde stationary gas engine oil (SGEO) in comparison with SAE 40 monograde SGEOs with the focus on two main areas. First, to demonstrate and quantify the positive impact of lower viscosity on the fuel consumption rate, and second to demonstrate the faster lubrication of hard to reach points in the engine during startup. The current industry recognized fuel efficiency test methods for passenger car and on-road diesel engine sectors are not suitable for evaluating the fuel efficiency performance of a gas engine oil because of the significant differences in fuel type, engine operating conditions, and oil formulations. This paper, therefore, describes comparative studies of three different gas engine oils in a modern MAN E3262 E302 gas engine that was carefully adapted and fully instrumented. The performance of each oil with respect to fuel efficiency was assessed in an extensive program comprising endurance testing, stationary tests on various load/speed points and dynamic tests running the engine fired as well as non-fired (motored). Another part of the test program explores the lubrication of hard to reach points in the engine, e.g. valve guide. The paper describes how the SAE 30 monograde oil results in faster lubrication of these parts during startup in comparison with the SAE 40 oils.

A Boundary Lubrication Friction Model Sensitive to Detailed Engine Oil Formulation in an Automotive Cam/Follower Interface

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Rupesh Roshan ◽  
Martin Priest ◽  
Anne Neville ◽  
Ardian Morina ◽  
Xin Xia ◽  
...  
Keyword(s):  
Boundary Lubrication ◽  
Fuel Efficiency ◽  
Lubricant Additive ◽  
Friction Model ◽  
Operating Conditions ◽  
Valve Train ◽  
Engine Oil ◽  
Contact Friction ◽  
Boundary Lubrication Friction ◽  
Base Oil

Theoretical studies have shown that in severe operating conditions, valve train friction losses are significant and have an adverse effect on fuel efficiency. However, recent studies have shown that existing valve train friction models do not reliably predict friction in boundary and mixed lubrication conditions and are not sensitive to lubricant chemistry. In these conditions, the friction losses depend on the tribological performance of tribofilms formed as a result of surface–lubricant additive interactions. In this study, key tribological parameters were extracted from a direct acting tappet type Ford Zetec SE (Sigma) valve train, and controlled experiments were performed in a block-on-ring tribometer under conditions representative of boundary lubrication in a cam and follower contact. Friction was recorded for the tribofilms formed by molybdenum dithiocarbamate (MoDTC), zinc dialkyldithiophosphate (ZDDP), detergent (calcium sulfonate), and dispersant (polyisobutylene succinimide) additives in an ester-containing synthetic polyalphaolefin (PAO) base oil on AISI E52100 steel components. A multiple linear regression technique was used to obtain a friction model in boundary lubrication from the friction data taken from the block-on-ring tribometer tests. The model was developed empirically as a function of the ZDDP, MoDTC, detergent, and dispersant concentration in the oil and the temperature and sliding speed. The resulting friction model is sensitive to lubricant chemistry in boundary lubrication. The tribofilm friction model showed sensitivity to the ZDDP–MoDTC, MoDTC–dispersant, MoDTC–speed, ZDDP–temperature, detergent–temperature, and detergent–speed interactions. Friction decreases with an increase in the temperature for all ZDDP/MoDTC ratios, and oils containing detergent and dispersant showed high friction due to antagonistic interactions between MoDTC–detergent and MoDTC–dispersant additive combinations.

Numerical Investigation of the Effects of Axial Cylinder Bore Profiles on Piston Ring Radial Dynamics

2003 ◽  
Vol 125 (4) ◽  
pp. 1081-1089 ◽  
Author(s):  
Y. Piao ◽  
S. D. Gulwadi
Keyword(s):  
High Speed ◽  
Piston Ring ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Operating Conditions ◽  
Engine Oil ◽  
Oil Consumption ◽  
Ring Pack ◽  
Cylinder Bore

The role of cylinder bore shapes in engine performance has been the subject of several studies in recent years. In particular, the influence of bore distortion on oil consumption under high speed conditions has generated significant interest. In this paper, the effect of an axial bore profile on radial dynamics of a ring is investigated. Radial ring motions within grooves due to the axial bore profile can generate significant inertial effects and also have an impact on ring end-gap sizes and lubrication conditions at the ring-liner interfaces. The magnitude of such effects is dependent on the ring-pack configuration, engine operating conditions (speed and load) and axial bore profile details. These issues are investigated in this study due to their implication on engine oil consumption, friction and blow-by. The authors have developed an analytical expression to account for the effects of radial ring inertia due to an axial bore profile for implementation in a piston ring-pack simulation tool RINGPAK. Simulation results from a gasoline engine study are presented to illustrate the effects of engine speeds, ring tensions, and characteristics of axial bore profiles on ring radial dynamics and ring-liner lubrication. Relevant qualitative comparisons are made to experimental measurements available in the literature.

Low-sooting combustion in a small-bore high-speed direct-injection diesel engine using narrow-angle injectors

2008 ◽  
Vol 222 (10) ◽  
pp. 1927-1937 ◽  
Author(s):  
T-G Fang ◽  
R E Coverdill ◽  
C-F F Lee ◽  
R A White
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Direct Injection ◽  
Fuel Efficiency ◽  
Operating Conditions ◽  
Injection Timing ◽  
Exhaust Pipe ◽  
Injection Angle ◽  
Direct Injection Diesel Engine ◽  
Combustion Flame

An optically accessible high-speed direct-injection diesel engine was used to study the effects of injection angles on low-sooting combustion. A digital high-speed camera was employed to capture the entire cycle combustion and spray evolution processes under seven operating conditions including post-top-dead centre (TDC) injection and pre-TDC injection strategies. The nitrogen oxide (NO x) emissions were also measured in the exhaust pipe. In-cylinder pressure data and heat release rate calculations were conducted. All the cases show premixed combustion features. For post-TDC injection cases, a large amount of fuel deposition is seen for a narrower-injection-angle tip, i.e. the 70° tip, and ignition is observed near the injector tip in the centre of the bowl, while for a wider-injection-angle tip, namely a 110° tip, ignition occurs near the spray tip in the vicinity of the bowl wall. The combustion flame is near the bowl wall and at the central region of the bowl for the 70° tip. However, the flame is more distributed and centralized for the 110° tip. Longer spray penetration is found for the pre-TDC injection timing cases. Liquid fuel impinges on the bowl wall or on the piston top and a fuel film is formed. Ignition for all the pre-TDC injection cases occur in a distributed way in the piston bowl. Two different combustion modes are observed for the pre-TDC injection cases including a homogeneous bulky combustion flame at earlier crank angles and a heterogeneous film combustion mode with luminous sooting flame at later crank angles. In terms of soot emissions, NO x emissions, and fuel efficiency, results show that the late post-TDC injection strategy gives the best performance.

Nonlinear Rotordynamics of Automotive Turbochargers: Predictions and Comparisons to Test Data

2005 ◽  
Author(s):  
Luis San Andre´s ◽  
Juan Carlos Rivadeneira ◽  
Murali Chinta ◽  
Kostandin Gjika ◽  
Gerry LaRue
Keyword(s):  
Test Data ◽  
Computational Design ◽  
Design Tool ◽  
Operating Conditions ◽  
Fluid Film ◽  
Engine Oil ◽  
Feed Pressure ◽  
Side Load ◽  
Linear And Nonlinear ◽  
Nonlinear Rotordynamics

Passenger vehicle turbochargers (TCs) offer increased engine power and efficiency in an ever-competitive marketplace. Turbochargers operate at high rotational speeds and use engine oil to lubricate fluid film bearing supports (radial and axial). However, TCs are prone to large amplitudes of sub-synchronous shaft motion over wide ranges of their operating speed. Linear rotordynamic tools cannot predict the amplitudes and multiple frequency shaft motions. A comprehensive nonlinear rotordynamics model coupled to a complete fluid-film-bearing model solves in real time the dynamics of automotive turbochargers. The computational design tool predicts the limit cycle response for several inner and outer film clearances and operating conditions including rotor speed and lubricant feed pressure. Substantial savings in product development and prototype testing are the benefits of the present development. The paper presents predictions of the linear and nonlinear shaft motion of an automotive turbocharger supported on a semi-floating ring bearing. The shaft motion predictions are compared to measurements of shaft motion at the compressor nose for speeds up to 240 krpm, and for lubricant inlet pressure of 4 bar at 150°C. Linear and nonlinear rotordynamic models reproduce very well the test data for synchronous response to imbalance. The nonlinear results show two sub-synchronous whirl frequencies whose large magnitudes agree well with the measurements. A large side load predicted for this turbocharger must be considered for accurate prediction of the rotordynamic response.

Numerical Investigation of the Effects of Axial Cylinder Bore Profiles on Piston Ring Radial Dynamics

2002 ◽  
Author(s):  
Y. Piao ◽  
S. D. Gulwadi
Keyword(s):  
High Speed ◽  
Piston Ring ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Operating Conditions ◽  
Engine Oil ◽  
Oil Consumption ◽  
Ring Pack ◽  
Cylinder Bore

The role of cylinder bore shapes in engine performance has been the subject of several studies in recent years. In particular, the influence of bore distortion on oil consumption under high speed conditions has generated significant interest. In this paper, the effect of an axial bore profile on radial dynamics of a ring is investigated. Radial ring motions within grooves due to the axial bore profile can generate significant inertial effects and also have an impact on ring end-gap sizes and lubrication conditions at the ring-liner interfaces. The magnitude of such effects is dependent on the ring-pack configuration, engine operating conditions (speed and load) and axial bore profile details. These issues are investigated in this study due to their implication on engine oil consumption, friction and blow-by. The authors have developed an analytical expression to account for the effects of radial ring inertia due to an axial bore profile for implementation in a piston ring–pack simulation tool RINGPAK. Simulation results from a gasoline engine study are presented to illustrate the effects of engine speeds, ring tensions and characteristics of axial bore profiles on ring radial dynamics and ring-liner lubrication. Relevant qualitative comparisons are made to experimental measurements available in the literature.

Simulation Driven Design Workflow for Aircraft Gearbox

2020 ◽  
Author(s):  
Youn Park ◽  
Dragi Gasevski ◽  
Marlow Springer ◽  
Milos Stanic ◽  
Viraj Kulkarni ◽  
...  
Keyword(s):  
Systems Engineering ◽  
Minimum Weight ◽  
Fuel Efficiency ◽  
Real Life ◽  
Operating Conditions ◽  
System Level ◽  
Unit Weight ◽  
Seamless Integration ◽  
Simulation And Optimization ◽  
Performance Requirements

Abstract The aerospace industry is driven more than ever to reduce time and cost of developing aircrafts while reducing weight without compromising performance. This challenge cascades down to design of aircraft engines, where manufacturers are striving to deliver engines with higher fuel efficiency and power per unit weight. The challenge cascades down further to aerospace systems such as gearboxes. The focus of this paper is to addresses this challenge through application of model-based systems engineering and a design workflow based on simulation and optimization. A typical gearbox design starts with system level performance requirements such as power requirements, speed, torques and operating conditions. The goal is to design a minimum weight, manufacturable gearbox in the shortest possible time that meets the performance requirements. In this paper, authors present a design workflow developed for meeting this goal. The efficiency of the workflow presented here comes from the use of advanced simulation technologies, seamless integration of the workflow tasks, and modern and intuitive user experience. The proposed workflow focuses on design of housing and lubrication. This workflow is demonstrated on an aircraft engine accessories gearbox. Gear and bearing design are currently out of the scope of this paper and can be addressed in future work. Demonstrating a fully detailed workflow on a real-life gearbox housing with all the physics covered here would require many man-months of work and is outside the scope of authors’ IRAD funding. Instead, authors have presented a proof of concept of the workflow while providing key statistics to support the value and feasibility of the workflow.

Development of a Non-Contacting Mechanical Seal for High Performance Turbocharger Applications

2018 ◽  
Author(s):  
Daniel A. Nelson
Keyword(s):  
High Speed ◽  
High Performance ◽  
Piston Ring ◽  
Fuel Efficiency ◽  
Thermal Response ◽  
Operating Conditions ◽  
Mechanical Seal ◽  
Tribological Surfaces ◽  
Novel Approach ◽  
Automobile Engines

This paper presents the design and development of a non-contacting dry-gas mechanical seal for high performance automotive turbocharger applications. Turbochargers are increasingly being incorporated into high performance automobile engines to improve fuel efficiency, enhance energy recovery, and increase horsepower as compared with similar sized naturally aspirated engines. Minimizing the wear rate of tribological surfaces in the turbomachinery is critical to maximizing the reliability and durability of the turbocharger. A dry-gas seal for turbochargers and related technologies with 2 to 4 cm shafts has been developed. The seal provides a complete barrier between the bearing oil and compressor flow path and is capable of reverse pressure and high speed. The seal performance was evaluated for speeds between 60,000 to 80,000 RPM, pressure differentials between −0.8 (reverse pressure) to 6 bar, and temperatures between 20 to 200 °C. Structural and thermal response of the seal components to the operating conditions are analyzed using finite element methods and the tribological behavior of the seal rings are analyzed using computational fluid dynamics. The design is experimentally validated in a seal test stand. This novel approach reduces turbocharger blowby and shows no measurable wear when compared with piston ring seals.

scholarly journals Efficiency of disengaged wet brake packs

2018 ◽  
Vol 233 (6) ◽  
pp. 1562-1569 ◽  
Author(s):  
M Leighton ◽  
Nicholas Morris ◽  
Gareth Trimmer ◽  
Paul D King ◽  
Homer Rahnejat
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Fuel Efficiency ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Navier Stokes ◽  
Fluid Viscosity ◽  
Fluid Inertia ◽  
Systems Model ◽  
High Fluid

Key objectives in off-highway vehicular powertrain development are fuel efficiency and environmental protection. As a result, palliative measures are made to reduce parasitic frictional losses while sustaining machine operational performance and reliability. A potential key contributor to the overall power loss is the rotation of disengaged wet multi-plate pack brake friction. Despite the numerous advantages of wet brake pack design, during high-speed manoeuvre in highway travel or at start-up conditions, significant frictional power losses occur. The addition of recessed grooves on the brake friction lining is used to dissipate heat during engagement. These complicate the prediction of performance of the system, particularly when disengaged. To characterise the losses produced by these components, a combined numerical and experimental approach is required. This paper presents a Reynolds-based numerical model including the effect of fluid inertia and squeeze film transience for prediction of performance of wet brake systems. Model predictions are compared with very detailed combined Navier–Stokes and Rayleigh-Plesset fluid dynamics analysis to ascertain its degree of conformity to representative physical operating conditions, as well the use of a developed experimental rig. The combined numerical and experimental approach is used to predict significant losses produced during various operating conditions. It is shown that cavitation becomes significant at low temperatures due to micro-hydrodynamic action, enhanced by high fluid viscosity. The magnitude of the losses for these components under various operating conditions is presented. The combined numerical-experimental study of wet multi-plate brakes of off-highway vehicles with cavitation flow dynamics has not hitherto been reported in the literature.

Air Bearing Interface Characteristics of Opposed Asymmetric Recording Head Sliders Flying on a 1 in. Titanium Foil Disk

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
James White
Keyword(s):  
Data Storage ◽  
High Speed ◽  
Hard Disk ◽  
Titanium Foil ◽  
Operating Conditions ◽  
Storage Device ◽  
Air Bearing ◽  
Mechanical Shock ◽  
Recording Head ◽  
Disk Interface

The current effort was motivated by the increasing appearance of data storage devices in small portable and mobile product formats and the need for these devices to deliver high storage capacity, low power requirements, and increased ruggedness. In order to address these requirements, this work considered the storage device to utilize a 1 in. titanium foil disk and a pair of opposed femtosized zero-load recording head sliders with asymmetrically configured air bearing surfaces. A titanium foil disk, due to its reduced thickness and relatively low mass density, requires less operational energy than a hard disk while providing storage densities and data transfer rates typical of a hard disk. The zero-load sliders were chosen in order to make negligible the air bearing interface normal force acting on the disk surface that can lead to high speed disk instability. The asymmetry of the slider air bearing surfaces, together with the disk dynamic flexibility, greatly improves the ability of the slider-disk interface to absorb substantial mechanical shock and other dynamic effects without the associated contact and impact typically observed with a hard disk. The current project evaluated the characteristics of this slider-disk air bearing interface for both static and unsteady operating conditions. Time dependent studies included a numerical simulation of the dynamic load process and the response to mechanical shock. A comparison with the performance of a hard disk interface was also included.

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