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Journal Article

A Metal Fibrous Filter for Diesel Hybrid Vehicles

2011-04-12
2011-01-0604
Trends towards lower vehicle fuel consumption and smaller environmental impact will increase the share of Diesel hybrids and Diesel Range Extended Vehicles (REV). Because of the Diesel engine presence and the ever tightening soot particle emissions, these vehicles will still require soot particle emissions control systems. Ceramic wall-flow monoliths are currently the key players in the Diesel Particulate Filter (DPF) market, offering certain advantages compared to other DPF technologies such as the metal based DPFs. The latter had, in the past, issues with respect to filtration efficiency, available filtration area and, sometimes, their manufacturing cost, the latter factor making them less attractive for most of the conventional Diesel engine powered vehicles. Nevertheless, metal substrate DPFs may find a better position in vehicles like Diesel hybrids and REVs in which high instant power consumption is readily offered enabling electrical filter regeneration.
Technical Paper

Minimization of Risks and Difficulties from DESIGN to MASS PRODUCTION for Powertrain Components and Modules

2011-04-12
2011-01-0524
One main general goal during product development in the passenger car industry as well as in the commercial vehicle industry is to reduce time to market. The customer wants to get the newest product and is not accepting the risk of any product call backs. This means the minimization of the risk of field claims for the manufacturer. The challenge to reach this goal is a capable volume production of each new product. To create a competitive, innovative product it is the task for design and simulation engineers in the development phase to design the product in view of function, efficiency, fatigue strength, optimized weight and optimized product costs. Additionally an agreement between design and industrial production planning is required. An early involvement of production engineers into the development of a product ensures design for manufacturing from the very beginning.
Technical Paper

Two-Cylinder Gasoline Engine Concept for Highly Integrated Range Extender and Hybrid Powertrain Applications

2010-09-28
2010-32-0130
The demand for improved fuel economy and the request for Zero Emission within cities require complex powertrains with an increasing level of electrification already in a short-termed timeframe until 2025. According to general expectations the demand for Mild-Hybrid powertrains will increase significantly within a broad range of implementation through all vehicle classes as well as on electric vehicles with integrated Range Extender (RE) mainly for use in urban areas. Whereas Mild Hybrid Vehicles basically use downsized combustion engines at current technology level, vehicles with a high level of powertrain electrification allow significantly different internal combustion engine (ICE) concepts. At AVL, various engine concepts have been investigated and evaluated with respect to the key criteria for a Range Extender application. A Wankel rotary engine concept as well as an inline 2 cylinder gasoline engine turned out to be most promising.
Journal Article

Blowdown Interference on a V8 Twin-Turbocharged Engine

2011-04-12
2011-01-0337
The exhaust blowdown pulse from each cylinder of a multi-cylinder engine propagates through the exhaust manifold and can affect the in-cylinder pressure of other cylinders which have open exhaust valves. Depending on the firing interval between cylinders connected to the same exhaust manifold, this blowdown interference can affect the exhaust stroke pumping work and the exhaust pressure during overlap, which in turn affects the residual fraction in those cylinders. These blowdown interference effects are much greater for a turbocharged engine than for one which is naturally aspirated because the volume of the exhaust manifolds is minimized to improve turbocharger transient response and because the turbines restrict the flow out of the manifolds. The uneven firing order (intervals of 90°-180°-270°-180°) on each bank of a 90° V8 engine causes the blowdown interference effects to vary dramatically between cylinders.
Technical Paper

LES Simulation of Flame Propagation in a Direct-Injection SI-Engine to Identify the Causes of Cycle-to-Cycle Combustion Variations

2013-04-08
2013-01-1084
A Large-Eddy-Simulation (LES) approach is applied to the calculation of multiple SI-engine cycles in order to study the causes of cycle-to-cycle combustion variations. The single-cylinder research engine adopted in the present study is equipped with direct fuel-injection and variable valve timing for both the intake and exhaust side. Operating conditions representing cases with considerably different scatter of the in-cylinder pressure traces are selected to investigate the causes of the cycle-to-cycle combustion variations. In the simulation the engine is represented by a coupled 1D/3D-CFD model, with the combustion chamber and the intake/exhaust ports modeled in 3D-CFD, and the intake/exhaust pipework set-up adopting a 1D-CFD approach. The adopted LES flow model is based upon the well-established Smagorinsky approach. Simulation of the fuel spray propagation process is based upon the discrete droplet model.
Technical Paper

Combining Thermodynamics and Design Optimization for Finding ICE Downsizing Limits

2014-04-01
2014-01-1098
The mass and overall dimensions of massively downsized engines for very high bmep (up to 35 bar) cannot be estimated by scaling of designs already available. Simulation methods coupling different levels of method profoundness, as 1-D methods, e.g., GT Suite/GT Power with in-house codes for engine mechanical efficiency assessment and preliminary design of boosting devices (a virtual compressor and a turbine), were used together with optimization codes based on genetic algorithms. Simultaneously, the impact of optimum cycle on cranktrain components dimensions (especially cylinder bore spacing), mass and inertia force loads were estimated since the results were systematically stored and analyzed in Design Assistance System DASY, developed by the authors for purposes of early-stage conceptual design. General thermodynamic cycles were defined by limiting parameters (bmep, burning duration, engine speed and turbocharger efficiency only).
Journal Article

Computational Study of the Aerodynamics of a Realistic Car Model by Means of RANS and Hybrid RANS/LES Approaches

2014-04-01
2014-01-0594
The aerodynamic properties of a BMW car model, representing a 40%-scaled model of a relevant car configuration, are studied computationally by means of the Unsteady RANS (Reynolds-Averaged Navier-Stokes) and Hybrid RANS/LES (Large-Eddy Simulation) approaches. The reference database (geometry, operating parameters and surface pressure distribution) are adopted from an experimental investigation carried out in the wind tunnel of the BMW Group in Munich (Schrefl, 2008). The present computational study focuses on validation of some recently developed turbulence models for unsteady flow computations in conjunction with the universal wall treatment combining integration up to the wall and high Reynolds number wall functions in such complex flow situations. The turbulence model adopted in both Unsteady RANS and PANS (Partially-Averaged Navier Stokes) frameworks is the four-equation ζ − f formulation of Hanjalic et al. (2004) based on the Elliptic Relaxation Concept (Durbin, 1991).
Technical Paper

Comparison of Particle Number Measurements from the Full Dilution Tunnel, the Tailpipe and Two Partial Flow Systems

2010-04-12
2010-01-1299
The regulation of particle number (PN) has been introduced in the Euro 5/6 light-duty vehicle legislation, as a result of the light duty inter-laboratory exercise of the Particle Measurement Program (PMP). The heavy-duty inter-laboratory exercise investigates whether the same or a similar procedure can be applied to the heavy-duty regulation. In the heavy-duty exercise two "golden" PN systems sample simultaneously; the first from the full dilution tunnel and the second from the partial flow system. One of the targets of the exercise is to compare the PN results from the two systems. In this study we follow a different approach: We use a PMP compliant system at different positions (full flow, partial flow and tailpipe) and we compare its emissions with a "reference" system always sampling from the full flow dilution tunnel.
Technical Paper

Tool Based Calibration with the OBDmanager

2010-04-12
2010-01-0249
At the moment the documentation of failure inhibition matrices and the fault path management for different controller types and different vehicle projects are mainly maintained manually in individual Excel tables. This is not only time consuming but also gives a high potential for fault liability. In addition there is also no guarantee that the calibration of these failure inhibition matrices and its fault path really works. Conflicting aims between costs, time and fault liability require a new approach for the calibration, documentation and testing of failure inhibition matrices and the complete Diagnostic System Management (DSM) calibration. The standardization and harmonization of the Diagnostic System Management calibration for different calibration projects and derivates is the first step to reduce time and costs. Creating a master calibration for the conjoint fault paths and labels provides a significant reduction of efforts.
Journal Article

Development of the Combustion System for a Flexible Fuel Turbocharged Direct Injection Engine

2010-04-12
2010-01-0585
Gasoline turbocharged direct injection (GTDI) engines, such as EcoBoost™ from Ford, are becoming established as a high value technology solution to improve passenger car and light truck fuel economy. Due to their high specific performance and excellent low-speed torque, improved fuel economy can be realized due to downsizing and downspeeding without sacrificing performance and driveability while meeting the most stringent future emissions standards with an inexpensive three-way catalyst. A logical and synergistic extension of the EcoBoost™ strategy is the use of E85 (approximately 85% ethanol and 15% gasoline) for knock mitigation. Direct injection of E85 is very effective in suppressing knock due to ethanol's high heat of vaporization - which increases the charge cooling benefit of direct injection - and inherently high octane rating. As a result, higher boost levels can be achieved while maintaining optimal combustion phasing giving high thermal efficiency.
Technical Paper

Reducing Emissions and Improving Fuel Economy by Optimized Combustion of Alternative Fuels

2011-10-06
2011-28-0050
Alternative fuels, especially fuels based on biological matter, are gaining more and more attention. Not only as a pure substitute of oil but also in terms of a possibility for further reduction in emission and as an option to improve the global CO2 balance. For improving the engine performance (emissions, fuel consumption, torque and drivability) the adjustment of fuel injection, the fuel evaporation process and the combustion process itself is paramount. In order to exploit the full potential of alternative fuels excellent knowledge of the fuel properties, including the impact on ignition and flame propagation, is required. This needs suitable tools for analysis of the fuel injection and combustion process. These tools have to support the optimization of the combustion system and the dynamic engine calibration for lowest emissions and most efficient use of fuel. As the term “Alternative Fuels” covers a very wide area a brief overview on available fuel types will be made.
Technical Paper

Systematic Development of Hybrid Systems for Commercial Vehicles

2011-10-06
2011-28-0064
The reduction of CO₂ emissions represents a major goal of governments worldwide. In developed countries, approximately 20% of the CO₂ emissions originate from transport, one third of this from commercial vehicles. CO₂ emission legislation is in place for passenger cars in a number of major markets. For commercial vehicles such legislation was also already partly published or is under discussion. Furthermore the commercial vehicles market is very cost sensitive. Thus the major share of fuel cost in the total cost of ownership of commercial vehicles was already in the past a major driver for the development of efficient drivetrain solutions. These aspects make the use of new powertrain technologies, specifically hybridization, mandatory for future commercial powertrains. While some technologies offer a greater potential for CO₂ reduction than others, they might not represent the overall optimum with regard to the total cost of ownership.
Technical Paper

Accuracy of Particle Number Measurements from Partial Flow Dilution Systems

2011-09-11
2011-24-0207
The measurement of the particle number (PN) concentration of non-volatile particles ≻23 nm was introduced in the light-duty vehicles regulation; the heavy-duty regulation followed. Based on the findings of the Particle Measurement Program (PMP), heavy-duty inter-laboratory exercise, the PN concentration measurement can be conducted either from the full dilution tunnel with constant volume sampling (CVS) or from the partial flow dilution system (PFDS). However, there are no other studies that investigate whether the PN results from the two systems are equivalent. In addition, even the PMP study never investigated the uncertainty that is introduced at the final result from the extraction of a flow by a PN system from the PFDS. In this work we investigate the uncertainty for the three possible cases, i.e., considering a constant extracted flow from the PFDS, sending a signal with 1 Hz frequency to the PFDS, or feeding back the extracted flow to the PFDS.
Technical Paper

Cylinder- and Cycle Resolved Particle Formation Evaluation to Support GDI Engine Development for Euro 6 Targets

2011-09-11
2011-24-0206
Combustion of premixed stoichiometric charge is free of soot particle formation. Consequently, the development of direct injection (DI) spark ignition (SI) engines aims at providing premixed charge to avoid or minimize soot formation in order to meet particle emissions targets. Engine development methods not only need precise engine-out particle measurement instrumentation but also sensors and measurement techniques which enable identification of in-cylinder soot formation sources under all relevant engine test conditions. Such identification is made possible by recording flame radiation signals and with analysis of such signals for premixed and diffusion flame signatures. This paper presents measurement techniques and analysis methods under normal engine and vehicle test procedures to minimize sooting combustion modes in transient engine operation.
Technical Paper

Feasibility of Particulate Mass and Number Measurement with Portable Emission Measurement Systems (PEMS) for In-Use Testing

2011-09-11
2011-24-0199
Different particulate mass (PM) portable emission measurement systems (PEMS) were evaluated in the lab with three heavy-duty diesel engines which cover a wide range of particle emission levels. For the two engines without Diesel Particulate Filters (DPF) the proportional partial flow dilution systems SPC-472, OBS-TRPM, and micro-PSS measured 15% lower PM than the full dilution tunnel (CVS). The micro soot sensor (MSS), which measures soot in real time, measured 35% lower. For the DPF-equipped engine, where the emissions were in the order of 2 mg/kWh, the systems had differences from the CVS higher than 50%. For on-board testing a real-time sensor is necessary to convert the gravimetric (filter)-based PM to second-by-second mass emissions. The detection limit of the sensor, the particle property it measures (e.g., number, surface area or mass, volatiles or non-volatiles) and its calibration affect the estimated real-time mass emissions.
Technical Paper

CAE Process for Developing Cylinder Head Design Including Statistical Correlation and Shape Optimization

2010-04-12
2010-01-0494
Design of cylinder heads involves complex constraints that must satisfy thermal, strength, performance, and manufacturing requirements which present a great challenge for successful development. During development of a new highly loaded cylinder head, CAE methods predicted unacceptable fatigue safety factors for the initial prototype design. Hydropulsator component testing was undertaken and the results were correlated with the analysis predictions using a statistical method to calculate failure probability. Shape optimization was undertaken to improve high cycle fatigue safety in vulnerable regions of the cylinder head water jacket for the subsequent design release. The optimization process provided more efficient design guidance than previously discovered through a traditional iterative approach. Follow-on investigations examined other shape optimization software for fatigue improvement in the cylinder head.
Technical Paper

A Novel Ultrasonic Intake Air Flow Meter for Test Bed Applications

2013-01-09
2013-26-0118
The development process of a combustion engine is now a days strongly influenced by future emission regulations which require further reduction in fuel consumption and precise control of combustion process based on Intake air measurement, during engine development. Intake air flow meters clearly differentiate themselves from typical industrial gas flow meters because of their ability to measure extremely dynamic phenomenon of combustion engine. Thus, high internal data acquisition rate, short response time, ability to measure pulsating and reverse flows with lower measurement uncertainty are the factors that ensures the reliability of the results without being affected by ambient influences, sensor contamination or sensor aging. The AVL developed FLOWSONIX™ is based on ultrasonic transit time measuring principle with broad-band Capacitive Ultrasonic Transducer (CUT) characterized by an excellent air impedance matching strongly distinguishes itself by fulfilling all those requirements.
Technical Paper

Advanced Methods for Calibration and Validation of Diesel-ECU Models Using Emission and Fuel Consumption Optimization and Prediction During Dynamic Warm Up Tests (EDC)

2013-01-09
2013-26-0113
A calibration and validation workflow will be presented in this paper, which utilizes common static global models for fuel consumption, NOx and soot. Due to the applicability for warm-up tests, e.g. New European Driving Cycle (NEDC), the models need to predict the temperature influence and will be fitted with measuring data from a conditioned engine test bed. The applied model structure consisting of a number of global data-based sub-models is configured especially for the requirements of multi-injection strategies of common rail systems. Additionally common global models for several constant coolant water temperature levels are generated and the workflow tool supports the combination and segmentation of global nominal map with temperature correction maps for seamless and direct ECU setting.
Technical Paper

Combustion Analysis for In - Vehicle Application

2013-01-09
2013-26-0115
Traditional power train development work is concentrated mainly on test bed and on chassis dyno. Though we can simulate a lot of real world conditions on testbed and chassis dyno today, on road application work willis gaining more attention. This means that strategies and tools for invehicle testing under real world conditions are becoming more important. Emission, performance, fuel economy, combustion noise and driving comfort are linked to combustion quality, i.e. quality of fuel mixture preparation and flame propagation. The known testing and research equipment is only partly or not at all applicable for in-vehicle development work. New tools for on the road testing are required. Following, a general view on in-vehicle power train testing will be given. Additionally, new ways to investigate cylinder and cycle specific soot formation in GDI engines with fiber optic tools will be presented.
Technical Paper

Functional Integration as Key for Affordable Electrified Passenger Car Powertrains

2013-01-09
2013-26-0067
Further fuel efficiency improvements are mandatory in order to achieve the CO2 emission limits envisaged in the future. Electrification of the powertrain is seen as one of the key technologies to achieve these future goals. However, electrification of the power train typically goes with a massive cost increase of the overall system itself which is especially crucial for cost sensitive markets like India. AVL's approach to cost reduction for comparable performance and fuel consumption target values is an integration of functions. This paper demonstrates that, through a deeper interaction of the single powertrain components, further fuel efficiency optimization may be gained. System optimization at a powertrain level enables the achievement of future powertrain targets with respect to fuel efficiency and performance with only minimal and reduced requirements at a component level (i.e. combustion engine, electric drive, transmission and battery).
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