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Journal Article

Influence of Injection Timing and Piston Bowl Geometry on PCCI Combustion and Emissions

2009-04-20
2009-01-1102
Premixed Charge Compression Ignition (PCCI), a Low Temperature Combustion (LTC) strategy for diesel engines is of increasing interest due to its potential to simultaneously reduce soot and NOx emissions. However, the influence of mixture preparation on combustion phasing and heat release rate in LTC is not fully understood. In the present study, the influence of injection timing on mixture preparation, combustion and emissions in PCCI mode is investigated by experimental and computational methods. A sequential coupling approach of 3D CFD with a Stochastic Reactor Model (SRM) is used to simulate the PCCI engine. The SRM accounts for detailed chemical kinetics, convective heat transfer and turbulent micro-mixing. In this integrated approach, the temperature-equivalence ratio statistics obtained using KIVA 3V are mapped onto the stochastic particle ensemble used in the SRM.
Journal Article

Assessment of Multiple Injection Strategies in a Direct-Injection Hydrogen Research Engine

2009-06-15
2009-01-1920
Hydrogen is widely considered a promising fuel for future transportation applications for both, internal combustion engines and fuel cells. Due to their advanced stage of development and immediate availability hydrogen combustion engines could act as a bridging technology towards a wide-spread hydrogen infrastructure. Although fuel cell vehicles are expected to surpass hydrogen combustion engine vehicles in terms of efficiency, the difference in efficiency might not be as significant as widely anticipated [1]. Hydrogen combustion engines have been shown capable of achieving efficiencies of up to 45 % [2]. One of the remaining challenges is the reduction of nitric oxide emissions while achieving peak engine efficiencies. This paper summarizes research work performed on a single-cylinder hydrogen direct injection engine at Argonne National Laboratory.
Technical Paper

Electronic Control Module Network and Data Link Development and Validation using Hardware in the Loop Systems

2009-10-06
2009-01-2840
Increasingly, the exchanges of data in complex ECM (Electronic Control Module) systems rely on multiple communication networks across various physical and network layers. This has greatly increased system flexibility and provided an excellent medium to create well-defined exchangeable interfaces between components; however this added flexibility comes with increased network complexity. A system-level approach allows for the optimization of data exchange and network configuration as well as the development of a comprehensive network failure strategy. Many current ECM systems utilize complex multi-network communication strategies to exchange and control data to components. Recently, Caterpillar implemented an HIL (Hardware-In-the-Loop) test system that provides an approach for developing and testing a comprehensive ECM network strategy.
Technical Paper

Correlation of Air Fuel Ratio with Ionization Signal Metrics in a Multicylinder Spark Ignited Engine

2009-04-20
2009-01-0584
Accurate individual cylinder Air Fuel Ratio (AFR) feedback provide opportunities for improved engine performance and reduced emissions in spark ignition engines. One potential measurement for individual cylinder AFR is in-cylinder ionization measured by employing the spark plug as a sensor. A number of previous investigations have studied correlations of the ionization signal with AFR and shown promising results. However the studies have typically been limited to single cylinders under restricted operating conditions. This investigation analyzes and characterizes the ionization signals in correlation to individual AFR values obtained from wide-band electrochemical oxygen sensors located in the exhaust runners of each cylinder. Experimental studies for this research were conducted on a 2.0L inline 4 cylinder spark ignited engine with dual independent variable cam phasing and an intake charge motion control valve.
Technical Paper

Linkage and Structural Optimization of an Earth Moving Machine

2010-04-12
2010-01-0496
Faced with competitive environments, pressure to lower development costs and aggressive timelines engineers are not only increasingly adopting numerical simulation techniques but are also embracing design optimization schemes to augment their efforts. These techniques not only provide more understanding of the trade-offs but are also capable of proactively guiding the decision making process. However, design optimization and exploration tools have struggled to find complete acceptance and are typically underutilized in many applications; especially in situations where the algorithms have to compete with existing swift decision making processes. In this paper we demonstrate how the type of setup and algorithmic choice can have an influence and make optimization more lucrative in a new product development atmosphere. We also present some results from a design exploration activity, involving linkage and structural development, of an earth moving machine application.
Technical Paper

Modeling Techniques to Support Fuel Path Control in Medium Duty Diesel Engines

2010-04-12
2010-01-0332
In modern production diesel engine control systems, fuel path control is still largely conducted through a system of tables that set mode, timing and injection quantity and with common rail systems, rail pressure. In the hands of an experienced team, such systems have proved so far able to meet emissions standards, but they lack the analytical underpinning that lead to systematic solutions. In high degree of freedom systems typified by modern fuel injection, there is substantial scope to deploy optimising closed loop strategies during calibration and potentially in the delivered product. In an optimising controller, a digital algorithm will explicitly trade-off conflicting objectives and follow trajectories during transients that continue to meet a defined set of criteria. Such an optimising controller must be based on a model of the system behaviour which is used in real time to investigate the consequences of proposed control actions.
Technical Paper

Model Integration and Hardware-in-the-Loop (HiL) Simulation Design for the Testing of Electric Power Steering Controllers

2016-04-05
2016-01-0029
Abstract The Electronic Control Unit (ECU) of an Electric Power Steering (EPS) system is a core device to decide how much assistance an electric motor applies on a steering wheel. The EPS ECU plays an important role in EPS systems. The effectiveness of an ECU needs to be thoroughly tested before mass production. Hardware-in-the-loop simulation provides an efficient way for the development and testing of embedded controllers. This paper focuses on the development of a HiL system for testing EPS controllers. The hardware of the HiL system employs a dSPACE HiL simulator. The EPS plant model is an integrated model consisting of a Vehicle Dynamics model of the dSPACE Automotive Simulation Model (ASM) and the Nexteer Steering model. The paper presents the design of an EPS HiL system, the simulation of sensors and actuators, the functions of the ASM Vehicle Dynamics model, and the integration method of the ASM Vehicle Dynamics model with a Steering model.
Technical Paper

Carbureted SI Engine Air Flow Measurements

2016-04-05
2016-01-1082
Abstract Measurement of internal combustion engine air flow is challenging due to the required modification of the intake system and subsequent change in the air flow pattern. In this paper, various surge tank volumes were investigated to improve the accuracy of measuring air flow rate into a 674-cm3, four-stroke, liquid-cooled, internal combustion engine. According to the experimental results, when the venturi meter is used to measure the intake air flow rate, an air surge tank is required to be installed downstream of the venturi to smoothen the air flow. Moreover, test results revealed that increasing air surge tank volume beyond a limit could have a negative effect on the engine performance parameters especially in carbureted engines where controlling AFR is difficult. Although the air flow rate into the engine changed with increasing tank volume, the air-fuel ratio was leaner for smaller tank volumes.
Technical Paper

A Comparative Analysis for Optimal Control of Power Split in a Fuel Cell Hybrid Electric Vehicle

2016-04-05
2016-01-1189
Power split in Fuel Cell Hybrid Electric Vehicles (FCHEVs) has been controlled using different strategies ranging from rule-based to optimal control. Dynamic Programming (DP) and Model Predictive Control (MPC) are two common optimal control strategies used in optimization of the power split in FCHEVs with a trade-off between global optimality of the solution and online implementation of the controller. In this paper, both control strategies are developed and tested on a FC/battery vehicle model, and the results are compared in terms of total energy consumption. In addition, the effects of the MPC prediction horizon length on the controller performance are studied. Results show that by using the DP strategy, up to 12% less total energy consumption is achieved compared to MPC for a charge sustaining mode in the Urban Dynamometer Driving Schedule (UDDS) drive cycle.
Journal Article

Experimental and Numerical Study of Flame Kernel Formation Processes of Propane-Air Mixture in a Pressurized Combustion Vessel

2016-04-05
2016-01-0696
Abstract Fuel lean combustion and exhaust gas dilution are known to increase the thermal efficiency and reduce NOx emissions. In this study, experiments are performed to understand the effect of equivalence ratio on flame kernel formation and flame propagation around the spark plug for different low turbulent velocities. A series of experiments are carried out for propane-air mixtures to simulate engine-like conditions. For these experiments, equivalence ratios of 0.7 and 0.9 are tested with 20 percent mass-based exhaust gas recirculation (EGR). Turbulence is generated by a shrouded fan design in the vicinity of J-spark plug. A closed loop feedback control system is used for the fan to generate a consistent flow field. The flow profile is characterized by using Particle Image Velocimetry (PIV) technique. High-speed Schlieren visualization is used for the spark formation and flame propagation.
Technical Paper

Investigating Limitations of a Two-Zone NOx Model Applied to DI Diesel Combustion Using 3-D Modeling

2016-04-05
2016-01-0576
Abstract A two-zone NOx model intended for 1-D engine simulations was developed and used to model NOx emissions from a 2.5 L single-cylinder engine. The intent of the present work is to understand key aspects of a simple NOx model that are needed for predictive accuracy, including NOx formation and destruction phenomena in a DI Diesel combustion system. The presented two-zone model is fundamentally based on the heat release rate and thermodynamic incylinder data, and uses the Extended Zeldovich mechanism to model NO. Results show that the model responded very well to changes in speed, load, injection timing, and EGR level. It matched measured tail pipe NOx levels within 20%, using a single tuning setup. When the model was applied to varied injection rate shapes, it showed correct sensitivity to speed, load, injection timing, and EGR level, but the absolute level was well outside the target accuracy. The same limitation was seen when applying the Plee NOx model.
Journal Article

Residual Stress Distributions in Rectangular Bars Due to High Rolling Loads

2016-04-05
2016-01-0424
Abstract In this paper, residual stress distributions in rectangular bars due to rolling or burnishing at very high rolling or burnishing loads are investigated by roll burnishing experiments and three-dimensional finite element analyses using ABAQUS. First, roll burnishing experiments on rectangular bars at two roller burnishing loads are presented. The results indicate the higher burnishing load induces lower residual stresses and the higher burnishing load does not improve fatigue lives. Next, in the corresponding finite element analyses, the roller is modeled as rigid and the roller rolls on the flat surface of the bar with a low coefficient of friction. The bar material is modeled as an elastic-plastic strain hardening material with a nonlinear kinematic hardening rule for loading and unloading.
Journal Article

Reduction of Steady-State CFD HVAC Simulations into a Fully Transient Lumped Parameter Network

2014-05-10
2014-01-9121
Since transient vehicle HVAC computational fluids (CFD) simulations take too long to solve in a production environment, the goal of this project is to automatically create a lumped-parameter flow network from a steady-state CFD that solves nearly instantaneously. The data mining algorithm k-means is implemented to automatically discover flow features and form the network (a reduced order model). The lumped-parameter network is implemented in the commercial thermal solver MuSES to then run as a fully transient simulation. Using this network a “localized heat transfer coefficient” is shown to be an improvement over existing techniques. Also, it was found that the use of the clustering created a new flow visualization technique. Finally, fixing clusters near equipment newly demonstrates a capability to track localized temperatures near specific objects (such as equipment in vehicles).
Journal Article

Development and Implementation of a Mapless, Model Based SCR Control System

2014-07-01
2014-01-9050
Abstract Various engine platforms employ Selective Catalytic Reduction (SCR) technology to reduce the tail pipe emissions of oxides of nitrogen (NOx) from diesel engines as part of an overall strategy to comply with the emission regulations in place in various countries. High levels of NOx conversion (greater than 98%) in SCR aftertreatment may provide operating margin to increase overall fuel efficiency. However, to realize the potential fuel efficiency gains, the SCR technology employed should achieve high NOx conversion with limited reductant slip over transient application cycles in addition to steady state operation. A new approach to SCR controls was developed and implemented. This approach does not rely on any maps to determine the amount of urea solution to be dosed, thus significantly reducing calibration and development time and effort when implementing the SCR technology on multiple engine platforms and applications.
Technical Paper

Understanding the Kalman/Vold-Kalman Order Tracking Filters' Formulation and Behavior

2007-05-15
2007-01-2221
The Kalman and Vold-Kalman order tracking filters have been implemented in commercial software since the early 90's. There are several mathematical formulations of filters that have been implemented by different software vendors. However, there have not been any papers that have been published which sufficiently explain the math behind these filters and discuss the actual implementations of the filters in software. In addition, upon generating the equations represented by these filters, solving the equations for datasets in excess of several hundred thousand datapoints is not trivial and has not been discussed in the literature. The papers which have attempted to cover these topics are generally vague and overly mathematically eloquent but not easily understandable by a practicing engineer.
Technical Paper

Evaluation of Electro-acoustic Techniques for In-Situ Measurement of Acoustic Absorption Coefficient of Grass and Artificial Turf Surfaces

2007-05-15
2007-01-2225
The classical methods of measuring acoustic absorption coefficient using an impedance tube and a reverberation chamber are well established [1, 2]. However, these methods are not suitable for in-situ applications. The two in-situ methods; single channel microphone (P- probe) and dual channel acoustic pressure and particle velocity (Pu-probe) methods based on measurement of impulse response functions of the material surface under test, provide considerable advantage in data acquisition, signal processing, ease and mobility of measurement setup. This paper evaluates the measurement techniques of these two in-situ methods and provides results of acoustic absorption coefficient of a commercial artificial Astroturf, a Dow quash material, and a grass surface.
Technical Paper

Characterizing the Effect of Automotive Torque Converter Design Parameters on the Onset of Cavitation at Stall

2007-05-15
2007-01-2231
This paper details a study of the effects of multiple torque converter design and operating point parameters on the resistance of the converter to cavitation during vehicle launch. The onset of cavitation is determined by an identifiable change in the noise radiating from the converter during operation, when the collapse of cavitation bubbles becomes detectable by nearfield acoustical measurement instrumentation. An automated torque converter dynamometer test cell was developed to perform these studies, and special converter test fixturing is utilized to isolate the test unit from outside disturbances. A standard speed sweep test schedule is utilized, and an analytical technique for identifying the onset of cavitation from acoustical measurement is derived. Effects of torque converter diameter, torus dimensions, and pump and stator blade designs are determined.
Technical Paper

Implementation of the Time Variant Discrete Fourier Transform as a Real-Time Order Tracking Method

2007-05-15
2007-01-2213
The Time Variant Discrete Fourier Transform was implemented as a real-time order tracking method using developed software and commercially available hardware. The time variant discrete Fourier transform (TVDFT) with the application of the orthogonality compensation matrix allows multiple tachometers to be tracked with close and/or crossing orders to be separated in real-time. Signal generators were used to create controlled experimental data sets to simulate tachometers and response channels. Computation timing was evaluated for the data collection procedure and each of the data processing steps to determine how each part of the process affects overall performance. Many difficulties are associated with a real-time data collection and analysis tool and it becomes apparent that an understanding of each component in the system is required to determine where time consuming computation is located.
Technical Paper

CFD Modeling of the Multiphase Flow and Heat Transfer for Piston Gallery Cooling System

2007-10-29
2007-01-4128
Numerical models are used in this study to investigate the oil flow and heat transfer in the piston gallery of a diesel engine. An experiment is set up to validate the numerical models. In the experiment a fixed, but adjustable steel plate is instrumented and pre-heated to a certain temperature. The oil is injected vertically upwards from an underneath injector and impinges on the bottom of the plate. The reduction of the plate temperature is recorded by the thermocouples pre-mounted in the plate. The numerical models are used to predict the temperature history at the thermocouple locations and validated with the experimental data. After the rig model validation, the numerical models are applied to evaluate the oil sloshing and heat transfer in the piston gallery. The piston motion is modeled by a dynamic mesh model, and the oil sloshing is modeled by the VOF (volume of fluid) multiphase model.
Technical Paper

Applying Ball Bearings to the Series Turbochargers for the Caterpillar® Heavy-Duty On-Highway Truck Engines

2007-10-30
2007-01-4235
Fuel is a significant portion of the operating cost for an on-highway diesel engine and fuel economy is important to the economics of shipping most goods in North America. Cat® ACERT™ engine technology is no exception. Ball bearings have been applied to the series turbochargers for the Caterpillar heavy-duty, on-highway diesel truck engines in order to reduce mechanical loss for improved efficiency and lower fuel consumption. Over many years of turbocharger development, much effort has been put into improving the aerodynamic efficiency of the compressor and turbine stages. Over the same span of time, the mechanical bearing losses of a turbocharger have not experienced a significant reduction in power consumption. Most turbochargers continue to use conventional hydrodynamic radial and thrust bearings to support the rotor. While these conventional bearings provide a low cost solution, they do create significant mechanical loss.
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