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Technical Paper

A Chemical-Kinetic Approach to the Definition of the Laminar Flame Speed for the Simulation of the Combustion of Spark-Ignition Engines

2017-09-04
2017-24-0035
The laminar burning speed is an important intrinsic property of an air-fuel mixture determining key combustion characteristics such as turbulent flame propagation. It is a function of the mixture composition (mixture fraction and residual gas mass fraction) and of the thermodynamic conditions. Experimental measurements of Laminar Flame Speeds (LFS) are common in literature, but initial pressure and temperature are limited to low values due to the test conditions: typical pressure values for LFS detection are lower than 25 bar, and temperature rarely exceeds 550 K. Actual trends in spark ignition engines are to increase specific power output by downsizing and supercharging, thus the flame front involves even more higher pressure and temperature since the beginning of combustion.
Technical Paper

A Mechatronics Approach for the Design of a New High Performance ElectroHydraulic Actuator

1999-09-14
1999-01-2853
This paper describes the design strategy adopted for developing a new high performance actuation system referred to as the ElectroHydraulic Actuator (EHA). The design approach can be divided into fives phases that include: pre-conceptual analysis, conceptual design, preliminary design, detailed design and, integration and test. An important aspect of the design process is the use of modeling and simulation for the analysis, sizing and selection of off-the-shelf parts, and for the detailed design of new custom made components. EHA is based on hydrostatic transmission. It is a unique device with its own characteristics and requires hydraulic components that are specifically tailored to its needs. A prototype of EHA has been produced and has demonstrated an extremely high level of performance. The performance of this prototype complies with design requirements and validates the chosen design approach.
Technical Paper

A Phenomenological Model for Soot Formation and Oxidation in Direct-Injection Diesel Engines

1995-10-01
952428
The concentration of carbonaceous particulate matter in the exhaust of diesel engines depends on the rates of formation and oxidation of soot in the combustion chamber. Soot forms early in the combustion process when local fuel-rich areas exist, whereas soot oxidation occurs later when more air is entrained into the fuel spray. Based on this understanding, a phenomenological combustion model is established. In the model, the cylinder volume is divided into four zones: a rich fuel spray core, a premixed-burning/burned gas zone, a mixing controlled burning zone and a lean air zone. Soot formation takes place in the mixing controlled burning zone where the local C/O ratio is above the critical value. Soot oxidation occurs in the premixed-burning/burned gas zone as air is entrained. By using a quasi-global chemical reaction scheme, the oxidation of soot particles by different species can be investigated.
Technical Paper

Accurate Measurement of PVT Data for PP/Gas and TPO/Gas Mixtures

2006-04-03
2006-01-0506
Foaming of a thermoplastic polyolefin (TPO) is gaining interests because of its superior mechanical properties of foamed automotive parts, such as lightweight and high performance to weight ratio, etc. In this context, understanding of the thermophysical properties of PP/gas and TPO/gas mixtures is critically important. This paper will present the newly developed experimental technique to accurately measure the swelling of PP and TPO due to gas dissolution at elevated temperatures and pressures. Our technique measures the geometry of the pendent drop accurately from the captured images to obtain the volume swelling data. It determines the boundary location of the polymer/gas sample accurately by magnifying the sample drop locally along its edge before capturing the image. The automated high-precision XY stage is chosen as the platform to control the motion of the CCD camera.
Technical Paper

An Experimental Investigation into the Characteristics of a Fast-Response Flame Ionization Detector for In-Cylinder Sampling

1999-10-25
1999-01-3538
The Cambustion fast-response flame ionization detector (FFID) has been successfully used for instantaneous exhaust port hydrocarbon (HC) concentration measurement in IC engines for a decade. Measurements of in-cylinder HC concentration have also been made, but these present greater challenge. As the sample transit time and the time constant of the system always change when the sampling pressure is changed, it is necessary to investigate the characteristics of the system before it was used for in-cylinder sampling. A unique method was designed to study the influence of the diameter and length of the transfer sample line and the operating parameters of the FFID on the transit time and time constant. A database of transit time and time constant was built up for different simulated in-cylinder pressures. The database can be used for correcting eventual in-cylinder HC concentration measurement.
Technical Paper

Application of Nonlinear Transformations to A/F Ratio and Speed Control in an IC Engine

1999-03-01
1999-01-0858
This paper presents the first application of the global feedback linearization method to an internal combustion (IC) engine. Through the application of this nonlinear control technique, the nonlinear coupled dynamics of the IC engine are globally linearized and decoupled. This represents a significant advance over previously published control approaches which rely on locally linearized dynamic models. With the IC engine dynamics globally linearized and decoupled, outer-loop controllers can be readily designed using simple linear tracking controller design methods, leading to very good dynamic response of three key IC engine outputs, air/fuel ratio, engine speed and manifold air pressure. In this paper, a standard IC engine model from the literature is first transformed to a controllable canonical form, required for the application of the global feedback linearization methods.
Technical Paper

Application of a Synchronization System for Control of Ground to Airplane Power Transfers

2004-11-02
2004-01-3211
Recent advances in the development of a more robust synchronization strategy has made it viable to propose a control system for a no-break power transfer in aerospace applications. The proposed system constitutes a combination of a multirate phase locked loop with a positive sequence detector. Synchronization to the positive sequence component, in the presence of unbalanced loads, minimizes the circulating real and reactive power. The amplitude, frequency, and phase of the airplane power source are made available. The no-break control system automatically sets the ground power unit to the frequency and phase of the aircraft power unit and adjusts its amplitude to the required level. The relays are then closed and the ground power unit is connected to the airplane load. The amplitude information is provided by an automatic gain control (AGC) loop.
Technical Paper

Behaviour of a Closed Loop Controlled Air Valve Type Mixer on a Natural Gas Fuelled Engine Under Transient Operation

1995-08-01
951911
Many current aftermarket natural gas conversions of gasoline fuelled spark ignited engines use an air-valve type mixer with closed loop control of the gas pressure. This control is often provided by an electronic integral controller that uses the output from an exhaust gas oxygen (EGO) sensor to control the duty cycle of a solenoid valve. By varying the duty cycle of this fuel control valve (FCV), the average pressure in the low pressure regulator (LPR) reference chamber and thus the gas pressure can be varied. The transient behaviour of these fuel systems is affected mainly by the mechanical response of the gas mixer and the LPR. The electronic controller can provide compensation only after the EGO sensor has detected an air-fuel ratio excursion. The main weaknesses of this type of fuel system seems to be associated with the finite response of the mixer and the LPR and by the use of an airflow dependent vacuum signal strength for control.
Technical Paper

Bluff-Body Stabilized Glow Plug Ignition of a Methanol-Fueled IDI Diesel Engine

1993-03-01
930935
Methanol, in common with other alternative fuels including natural gas and LPG, has autoignition characteristics which are poorly suited for use in compression ignition engines. Some sort of ignition assist has proven to be necessary. Considerable work has been carried out with hot surface (glow plug) ignition. The geometric relationship between the fuel injection nozzle and the glow plug is critical to achieving high efficiency and low emissions. Moreover, it is difficult to establish a single geometry which provides reliable ignition and stable operation over the entire range of engine speeds and loads. The work described in this paper investigated extending the range of operation of a particular glow plug/fuel injection nozzle geometry by placing the glow plug in the wake of a bluff body. Bluff-body flame stabilization is a well-known technique in continuous combustors. Experiments were carried out in a single-cylinder CFR cetane rating engine fueled with methanol.
Technical Paper

Concurrent Quantitative Laser-Induced Incandescence and SMPS Measurements of EGR Effects on Particulate Emissions from a TDI Diesel Engine

2002-10-21
2002-01-2715
A comparison of scanning mobility particle sizer (SMPS) and laser-induced incandescence (LII) measurements of diesel particulate matter (PM) was performed. The results reveal the significance of the aggregate nature of diesel PM on interpretation of size and volume fraction measurements obtained with an SMPS, and the accuracy of primary particle size measurements by LII. Volume fraction calculations based on the mobility diameter measured by the SMPS substantially over-predict the space-filling volume fraction of the PM. Correction algorithms for the SMPS measurements, to account for the fractal nature of the aggregate morphology, result in a substantial reduction in the reported volume. The behavior of the particulate volume fraction, mean and standard deviation of the mobility diameter, and primary particle size are studied as a function of the EGR for a range of steady-state engine speeds and loads for a turbocharged direct-injection diesel engine.
Technical Paper

Development and Calibration of One Dimensional Engine Model for Hardware-In-The-Loop Applications

2018-04-03
2018-01-0874
The present paper aims at developing an innovative procedure to create a one-dimensional (1D) real-time capable simulation model for a heavy-duty diesel engine. The novelty of this approach is the use of the top-level engine configuration, test cell measurement data, and manufacturer maps as opposite to common practice of utilizing a detailed 1D engine model. The objective is to facilitate effective model adjustments and hence further increase the application of Hardware-in-the-Loop (HiL) simulations in powertrain development. This work describes the development of Fast Running Model (FRM) in GT-SUITE simulation software. The cylinder and gas-path modeling and calibration are described in detail. The results for engine performance and exhaust emissions produced satisfactory agreement with both steady-state and transient experimental data.
Technical Paper

Effect of Closed Loop Fuel Control System Characteristics on Emissions from a Natural Gas-Fueled Engine

1993-10-01
932747
Some current aftermarket natural gas closed loop carburetion systems use an integral control strategy to maintain a fuel-air equivalence ratio centered in the peak conversion window of a three-way catalytic converter. Fuel control system performance under steady-state engine operating conditions can be characterized by the time-averaged value of the fuel-air equivalence ratio, the rich and lean excursion limits, and a skewness parameter that represents the non-symmetry of the time varying fuel-air equivalence ratio about the control value (ϕaverage). Using a representative aftermarket feedback control system, the effect of these parameters on the exhaust emissions of a natural-gas fueled four-cylinder engine has been investigated. In addition, the effect of EGO sensor characteristics on control system performance has been examined.
Technical Paper

Effect of Engine Operating Variables and Piston and Ring Parameters on Crevice Hydrocarbon Emissions

1994-03-01
940480
A study was performed to determine the effects of engine operating variables and piston and ring parameters on the crevice hydrocarbon emissions from a spark-ignition engine. Natural gas was used as the test fuel in an effort to isolate crevice mechanisms as the only major source of unburned hydrocarbons in the test engine's exhaust. The largest of the in-cylinder crevices, the piston ring pack crevices, were modified, both in size and accessibility, by altering the piston top land height and the number of piston rings and their end gaps. Each piston and ring configuration was subjected to a series of test sweeps of engine operating variables known to affect exhaust hydrocarbon emissions. None of the physical crevice modifications had any significant effect on the level of the exhaust hydrocarbon emissions, although the cycle-to-cycle repeatability of these emissions, measured with a fast hydrocarbon analyzer, was found to vary between the different configurations.
Technical Paper

Effect of Increasing Compression Ratio in a Light-Duty Natural Gas-Fueled Engine on Efficiency and Emissions

1993-10-01
932746
As a result of CAFE (corporate average fuel economy) requirements, the trend in passenger car engine design is to smaller displacement engines of higher specific output which provide reductions in vehicle driving cycle fuel consumption without an accompanying decrease in maximum power output. Design features such as four valves per cylinder and compact combustion chambers give these engines significantly different combustion characteristics than traditional pushrod OHV (overhead valve) engines. In general, their combustion chambers are fast burning, enabling the use of higher compression ratios without knock on unleaded gasoline. Since fuel consumption decreases with increasing compression ratio, and since natural gas has a substantially higher octane rating than the best unleaded gasoline, it would appear to be desirable to operate with even higher compression ratios in a dedicated natural gas engine.
Technical Paper

Emissions from Compression Ignition Engines with Animal-Fat-Derived Biodiesel Fuels

2014-04-01
2014-01-1600
Biodiesel and other renewable fuels are of interest due to their impact on energy supplies as well as their potential for carbon emissions reductions. Waste animal fats from meat processing facilities, which would otherwise be sent to landfill, have been proposed as a feedstock for biodiesel production. Emissions from biodiesel fuels derived from vegetable oils have undergone intense study, but there remains a lack of data describing the emissions implications of using animal fats as a biodiesel feedstock. In this study, emissions of NOx, unburned hydrocarbons and particulate matter from a compression ignition engine were examined. The particulate matter emissions were characterized using gravimetric analysis, elemental carbon analysis and transmission electron microscopy. The emissions from an animal fat derived B20 blend were compared to those from petroleum diesel and a soy derived B20 blend.
Technical Paper

Evaluation of Different Natural Gas Fueling Strategies During Throttle Transients

1996-10-01
961985
Throttle tip-in and tip-out tests on a 2.0 litre passenger car engine were performed using four different natural gas fuelling systems an air-valve or variable restriction type mixer, a venturi type mixer, central fuel injection, and port fuel injection. The in-cylinder fuel-air equivalence ratio, ϕ, was measured using a fast response flame ionization detector sampling about 7 mm from the spark plug gap. The data reveal characteristics of each fuel system's in-cylinder fuel-air ratio response and torque response.
Technical Paper

Evaluation of the Hydrogen-Fueled Rotary Engine for Hybrid Vehicle Applications

1996-02-01
960232
The hydrogen-fueled engine has been identified as a viable power unit for ultra-low emission senes-hybrid vehicles The absence of carbon in hydrogen fuel eliminates exhaust emissions of CO, CO2, and hydrocarbons, with the exception of small contributions from the combustion of lubricating oil Thus, the only regulated emission of a hydrogen-fueled engine is NOx, and the engine may be optimized to minimize NOx since the usual constraint of the NOx -hydrocarbon trade-off is not applicable Hydrogen-fueled homogeneous charge piston engines have, however, generally suffered from a variety of combustion difficulties, most notably a proclivity to ignition on hot surfaces such as exhaust valves, spark plug electrodes and deposits on combustion chamber walls The Wankel engine is particularly well suited to the use of hydrogen fuel, since its design minimizes most of the combustion difficulties In order to evaluate the possibilities offered by the hydrogen fueled rotary engine, dynamometer tests were conducted with a small (2 2kW) Wankel engine fueled with hydrogen Preliminary results show an absence of the combustion difficulties present with hydrogen-fueled homogenous charge piston engines The engine was operated unthrottled and power output was controlled by quality governing, i.e. by varying the fuel-air equivalence ratio on the lean side of stoichiometric The ability to operate with quality governing is made possible by the wide flammability limits of hydrogen-air mixtures NOx emissions are on the order of 5 ppm for power outputs up to 70% of the maximum attainable on hydrogen fuel Thus, by operating with very lean mixtures, which effectively derates the engine, very low NOx emissions can be achieved Since the rotary engine has a characteristically high power to weight ratio and a small volume per unit power compared to the piston engine, operating a rotary engine on hydrogen and derating the power output could yield an engine with extremely low emissions which still has weight and volume characteristics comparable to a gasoline-fueled piston engine Finally, since engine weight and volume affect vehicle design, and consequently in-use vehicle power requirements, those factors, as well as engine efficiency, must be taken into account in evaluating overall hybnd vehicle efficiency
Technical Paper

Exhaust Emission and Energy Consumption Effects from Hydrogen Supplementation of Natural Gas

1995-10-01
952497
An experiment was conducted to evaluate the efficiency and emissions of an engine fuelled with a mixture of natural gas and approximately 15% hydrogen by volume. This mixture, called Hythane™, was compared with natural gas fuel using engine efficiency and engine-out emissions at various engine operating conditions as the basis of comparison. Throughout most of the experiment, fuel mixtures were slightly rich of stoichiometry. It was found that at low engine loads, using the same spark timing, engine efficiency increased under HythaneTM fuelling but at higher engine loads, natural gas and Hythane™ had the same efficiency. At low engine speed and load conditions with the same spark timing, engine-out total hydrocarbon (THC) emissions were lower for Hythane™ fuelling. When compared on a carbon specific basis, however, natural gas hydrocarbon emissions were lower. At some test conditions, engine-out carbon monoxide (CO) emissions were lower under Hythane™.
Technical Paper

Experiments into the Flame Kernel Development in High Swirl Production Spark Ignition Engines

1999-10-25
1999-01-3544
The early flame kernel development period has a strong influence on the ultimate performance and emission characteristics of spark ignition engines. The fibre-optic instrumented spark plug, FOSP, is a tool used to characterise the early flame kernel development period without the need to modify production engines. Simultaneous in-cylinder pressure, fibre-optic spark plug and secondary ignition system voltage measurements have been made in the GM 2.8 L and the high swirl 3.1 L production engines modified to run on a single cylinder. The secondary ignition system voltages indicate that restrikes are occurring and that spark anemometry is a promising tool to extract information about the flow near the spark plug at the time of ignition. Further development of the technique is, however, required.
Technical Paper

Foamability of Thermoplastic Vulcanizates (TPVs) with Various Physical Blowing Agents (PBAs)

2006-04-03
2006-01-0972
Thermoplastic Vulcanizate (TPV) is a special class of Thermoplastic Elastomers (TPEs) made of a rubber/plastic polymer mixture in which the rubber phase is highly vulcanized. It is prepared by melt mixing a thermoplastic with an elastomer and by in-situ crosslinking of the rubber phase. Currently, TPV is replacing EPDM rubber dramatically because of the impressive advantages for automotive sealing applications. Some of the advantages of TPV compared to that of EPDM rubber are good gloss, recyclability, improved colorability, shorter cycle time and design flexibility. The development of TPV foaming technology is to fulfill the requirement of achieving lower cost, lighter weight and better fuel economy. Foaming of TPV has not been investigated extensively.
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