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Journal Article

Coking Phenomena in Nozzle Orifices of Dl-Diesel Engines

2009-04-20
2009-01-0837
Within a public founded project test cell investigations were undertaken to identify parameters which predominantly influence the development of critical deposits in injection nozzles. A medium-duty diesel engine was operated in two different coking cycles with a zinc-free lubricant. One of the cycles is dominated by rated power, while the second includes a wide area of the operation range. During the experiments the temperatures at the nozzle tip, the geometries of the nozzle orifice and fuel properties were varied. For a detailed analysis of the deposits methods of electron microscopy were deployed. In the course of the project optical access to all areas in the nozzle was achieved. The experiments were evaluated by means of the monitoring of power output and fuel flow at rated power. The usage of a SEM (scanning electron microscope) and a TEM (transmission electron microscope) revealed images of the deposits with a magnification of up to 160 000.
Journal Article

Operation Strategies for Controlled Auto Ignition Gasoline Engines

2009-04-20
2009-01-0300
Controlled Auto Ignition combustion systems have a high potential for fuel consumption and emissions reduction for gasoline engines in part load operation. Controlled auto ignition is initiated by reaching thermal ignition conditions at the end of compression. Combustion of the CAI process is controlled essentially by chemical kinetics, and thus differs significantly from conventional premixed combustion. Consequently, the CAI combustion process is determined by the thermodynamic state, and can be controlled by a high amount of residual gas and stratification of air, residual gas and fuel. In this paper both fundamental and application relevant aspects are investigated in a combined approach. Fundamental knowledge about the auto-ignition process and its dependency on engine operating conditions are required to efficiently develop an application strategy for CAI combustion.
Technical Paper

Mechanical Testing - Still Necessary!

2007-04-16
2007-01-1768
Over the last decades, the use of computers has become an integral part of the engine development process. Computer-based tools are increasingly used in the design process, and especially the layout of the various subsystems is conducted by means of simulation models. Computer-aided engineering plays a central role e.g. in the design of the combustion process as well as with regards to work performed in the area of engine mechanics, where CFD, FEM, and MBS are applied. As a parallel trend, it can be observed that various engine performance characteristics such as e.g. the specific power output and the power-to-weight ratio have undergone an enormous increase, a trend which to some extent counteracts the increase in safety against malfunction and failure. As yet, due to the constant need for further optimization, mechanical testing and verification processes have not become redundant, and it is assumed that they will remain indispensable for the foreseeable future.
Technical Paper

Gas Exchange Optimization and the Impact on Emission Reduction for HSDI Diesel Engines

2009-04-20
2009-01-0653
The main tasks for all future powertrain developments are: regulated emissions, CO2-values, comfort, good drivability, high reliability and affordable costs. One widely discussed approach for fuel consumption improvement within passenger car applications, is to incorporate the downsizing effect. To attain constant engine performance an increase of boost pressure and/or rated speed is mandatory. In both cases, the mass flow rate through the intake and exhaust ports and valves will rise. In this context, the impact of the port layout on the system has to be reassessed. In this paper, the impact of the port layout on a modern diesel combustion system will be discussed and a promising concept shall be described in detail. The investigations shown include flow measurements, PIV measurements of intake flow, CFD simulations of the flow field during intake and results from the thermodynamic test bench. One of the important topics is to prove the impact of the flow quality on the combustion.
Technical Paper

A New CFD Approach for Assessment of Swirl Flow Pattern in HSDI Diesel Engines

2010-09-28
2010-32-0037
The fulfillment of the aggravated demands on future small-size High-Speed Direct Injection (HSDI) Diesel engines requires next to the optimization of the injection system and the combustion chamber also the generation of an optimal in-cylinder swirl charge motion. To evaluate different port concepts for modern HSDI Diesel engines, usually quantities as the in-cylinder swirl ratio and the flow coefficient are determined, which are measured on a steady-state flow test bench. It has been shown that different valve lift strategies nominally lead to similar swirl levels. However, significant differences in combustion behavior and engine-out emissions give rise to the assumption that local differences in the in-cylinder flow structure caused by different valve lift strategies have noticeable impact. In this study an additional criterion, the homogeneity of the swirl flow, is introduced and a new approach for a quantitative assessment of swirl flow pattern is presented.
Technical Paper

Investigation of Predictive Models for Application in Engine Cold-Start Behavior

2004-03-08
2004-01-0994
The modern engine development process is characterized by shorter development cycles and a reduced number of prototypes. However, simultaneously exhaust after-treatment and emission testing is becoming increasingly more sophisticated. It is expected that predictive simulation tools that encompass the entire powertrain can potentially improve the efficiency of the calibration process. The testing of an ECU using a HiL system requires a real-time model. Additionally, if the initial parameters of the ECU are to be defined and tested, the model has to be more accurate than is typical for ECU functional testing. It is possible to enhance the generalization capability of the simulation, with neuronal network sub-models embedded into the architecture of a physical model, while still maintaining real-time execution. This paper emphasizes the experimental investigation and physical modeling of the port fuel injected SI engine.
Technical Paper

Simulation of Endurance and Thermo Cycle Testing for Highly Loaded HSDI Diesel Cylinder Heads

2001-10-01
2001-01-3226
Due to today's demands to reduce cost and product time to market, engineering procedures are increasingly using more sophisticated simulation techniques, instead of validation testing. Early implementation of CAE methods yield higher quality products, even with first prototypes, reducing the design iterations required to reach production quality. The strategy is to conduct specific evaluations of a realistic representation of the product while focusing on the key boundary conditions necessary to extract fatigue effects. Discussed in this paper are adequate CAE methods for early identification, evaluation and removal of conceptual and local structural weaknesses. Possible solutions gained from a computational optimization process are discussed for highly loaded HSDI diesel cylinder heads as a representative example.
Technical Paper

A Capacity Oriented Quality Assurance Method by Using Modular Containerized Test Cells

2002-11-19
2002-01-3456
The requirements for diesel and gasoline engines are continuously increasing with respect to emissions, fuel consumption and durability. Besides the engine development process the quality of the production engine itself has to be ensured. This paper discusses alternative philosophies and approaches in terms of the quality management process. Based on a detailed analysis of the required equipment advanced solutions are presented. Modular containerized test cells are described being equipped exactly to the current testing task ready to use in low infrastructure. The testing capacity of the facility can be adjusted to the actual production volume by simply removing or adding modular test cells. Thus, at every facility the testing tasks can be executed successfully and the investment can be kept low.
Technical Paper

A Modern Approach to Face Current and Future Testing Needs as Part of the Entire Development Process for Vehicles and Engines

2003-03-03
2003-01-1026
Nowadays lead times and quality demands for the development of entire vehicles, or components for them, require new methods, which must be supported by new tools. This paper describes the key demands to modern test cell equipment as well as solutions for the area of test cell management systems. An outlook to the evolution of the way of testing and the role of a test cell in the entire development process is given to discuss the needs and possible solutions of the future.
Technical Paper

Electric Drivetrain Testing Using Smart Green Technology

2012-04-16
2012-01-0338
Electric Motor and Drivetrain (Electric Mobility) Testing is a critical part of bringing any electric drivetrain into production. In this paper the requirements for an electric drivetrain test cell are discussed. The implementations of such test cells are described and examples of test results are provided. In particular, the energy and power requirements for PM brushless DC dynamometers and a PM brushless Unit Under Test (UUT) connected through a common dc bus are described. Simulation of the set-up is developed using MATLAB/Simulink and verified using empirical data from the test bench. The data used represents various steady state load conditions during durability test cycles. This “Smart Green Technology” concept not only reduces the energy requirement from the grid but also eliminates the inefficiencies related to putting energy back on the grid.
Technical Paper

Virtual Testing and Simulation Environment [Micro-HiL] for Engine and Aftertreatment Calibration and Development -Part 2

2012-04-16
2012-01-0928
The growing complexity of powertrain control strategies, software, and hardware is proving to be a significant challenge to the engineering community with regard to managing effective optimization to meet the desired performance. With an increased emphasis on shorter development time and the use of additional sensors and actuators becoming common, the increased dependence on physical models and use of complex interdependent control systems demands a thorough system understanding. This also encourages the use of process improvement tools to assist in an effective engineering process. In this paper, such a tool is discussed in its second phase of development. The Micro-HiL system will be discussed over a wide scope that focuses on the interests of the calibration and development community. The purpose of this paper is to provide an update on the Phase 2 activity of Micro-HiL development; Phase 1 was discussed in-depth at the 2011 SAE World Congress [2011-01-0703].
Technical Paper

Experimental Approach to Optimize Catalyst Flow Uniformity

2000-03-06
2000-01-0865
A uniform flow distribution at converter inlet is one of the fundamental requirements to meet high catalytic efficiency. Commonly used tools for optimization of the inlet flow distribution are flow measurements as well as CFD analysis. This paper puts emphasis on the experimental procedures and results. The interaction of flow measurements and CFD is outlined. The exhaust gas flow is transient, compressible and hot, making in-situ flow measurements very complex. On the other hand, to utilize the advantages of flow testing at steady-state and cold conditions the significance of these results has to be verified first. CFD analysis under different boundary conditions prove that - in a first approach - the flow situation can be regarded as a sequence of successive, steady-state situations. Using the Reynolds analogy a formula for the steady-state, cold test mass flow is derived, taking into account the cylinder displacement and the rated speed.
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