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Technical Paper

Feasibility Study of an Online Gasoline Fractionating System for use in Spark-Ignition Engines

2001-03-05
2001-01-1193
A fuel fractionating system is designed and commissioned to separate standard gasoline fuel into two components by evaporation. The system is installed on a Ricardo E6 single cylinder research engine for testing purposes. Laboratory tests are carried out to determine the Research Octane Number (RON) and Motoring Octane Number (MON) of both fuel fractions. Further tests are carried out to characterize Spark-Ignition (SI) and Controlled Auto-Ignition (CAI) combustion under borderline knock conditions, and these are related to results from some primary reference fuels. SI results indicate that an increase in compression ratio of up to 1.0 may be achieved, along with better charge ignitability if this system is used with a stratified charge combustion regime. CAI results show that the two fuels exhibit similar knock-resistances over a range of operating conditions.
Technical Paper

Engine Excitation Decomposition Methods and V Engine Results

2001-04-30
2001-01-1595
Engine excitation forces have been studied in the past using one of two methods; a lumped sum or a totally distributed approach. The lumped sum approach gives the well-understood engine inherent unbalance and the totally distributed approach is used in engine CAE models to determine the overall engine response. The approach that will be described in this paper identifies an intermediate level of sophistication. The methodology implemented considers single cylinder forces on the engine block, piston side thrust and main bearing forces, and decomposes them into their order content. The forces are then phased and geometrically distributed appropriately for each cylinder and then each order is analyzed relative to know distributions that are NVH concerns, V-block breathing, block side wall breathing, and block lateral and vertical bending.
Technical Paper

A New Method for Calculating Fluctuation Strength in Electric Motors

2001-04-30
2001-01-1588
In assessing the sound quality of electric motors (e.g., seat, mirror, and adjustable pedal motors), the sensation of Fluctuation Strength - a measure of intensity or frequency variation - has become important. For electric motors, it is typically caused by variation in the load, creating frequency modulation in the sound. An existing method for calculating Fluctuation Strength proved useful initially, but more extensive testing identified unacceptable performance. There were unacceptable levels of both false positives and false negatives. A new method is presented, which shows improved correlation with perceived fluctuation in sounds. Comparisons are made to the previous method and improvement is shown through examples of objective-subjective correlation for both seat motor sounds and adjustable pedal motor sounds. The new method is also shown to match subjective data from which the original measure of Fluctuation Strength was derived.
Technical Paper

Development and Validation of a Computational Process for Pass-By Noise Simulation

2001-04-30
2001-01-1561
The Indirect Boundary Element Analysis is employed for developing a computational pass-by noise simulation capability. An inverse analysis algorithm is developed in order to generate the definition of the main noise sources in the numerical model. The individual source models are combined for developing a system model for pass-by noise simulation. The developed numerical techniques are validated through comparison between numerical results and test data for component level and system level analyses. Specifically, the source definition capability is validated by comparing the actual and the computationally reconstructed acoustic field for an engine intake manifold. The overall pass-by noise simulation capability is validated by computing the maximum overall sound pressure level for a vehicle under two separate driving conditions.
Technical Paper

Analytical and Experimental Techniques in Solving the Plastic Intake Manifold NVH

2001-04-30
2001-01-1544
The intent of this paper is to summarize the work of the V8 power plant intake manifold radiated noise study. In a particular V8 engine application, customer satisfaction feedback provided observations of existing unpleasant noise at the driver's ear. A comprehensive analysis of customer data indicated that a range from 500 to 800 Hz suggests a potential improvement in noise reduction at the driver's ear. In this study the noise source was determined using various accelerometers located throughout the valley of the engine and intake manifold. The overall surface velocity of the engine valley was ranked with respect to the overall surface velocity of the intake manifold. An intensity mapping technique was also used to determine the major component noise contribution. In order to validate the experimental findings, a series of analysis was also conducted. The analysis model included not only the plastic intake manifold, but also the whole powertrain.
Technical Paper

Development of a Desulfurization Strategy for a NOx Adsorber Catalyst System

2001-03-05
2001-01-0510
The aggressive reduction of future diesel engine NOx emission limits forces the heavy- and light-duty diesel engine manufacturers to develop means to comply with stringent legislation. As a result, different exhaust emission control technologies applicable to NOx have been the subject of many investigations. One of these systems is the NOx adsorber catalyst, which has shown high NOx conversion rates during previous investigations with acceptable fuel consumption penalties. In addition, the NOx adsorber catalyst does not require a secondary on-board reductant. However, the NOx adsorber catalyst also represents the most sulfur sensitive emissions control device currently under investigation for advanced NOx control. To remove the sulfur introduced into the system through the diesel fuel and stored on the catalyst sites during operation, specific regeneration strategies and boundary conditions were investigated and developed.
Technical Paper

FordS Zero Emission P2000 Fuel Cell Vehicle

2000-11-01
2000-01-C046
The P2000 Fuel Cell Electric Vehicle developed by Ford Motor Company is the first full-performance, full-size passenger fuel cell vehicle in the world. This development process has resulted in a vehicle with performance that matches some of today's vehicles powered by internal combustion engines. The powertrain in Ford's P2000 FCEV lightweight aluminum vehicle consists of an Ecostar electric motor/transaxle and a fuel cell system developed with XCELLSiS-The Fuel Cell Engine Company (formerly dbb Fuel Cell Engines, Inc.). Ballard's Mark 700 series fuel cell stack is a main component in the fuel cell system. To support this new FCEV, Ford has constructed the first North American hydrogen refueling station capable of dispensing gaseous and liquid hydrogen. On-going research and development is progressing to optimize fuel cell vehicle performance and refueling techniques.
Technical Paper

Eliminating Piston Slap through a Design for Robustness CAE Approach

2003-05-05
2003-01-1728
Piston slap is a problem that plagues many engines. One of the most difficult aspects of designing to eliminate piston slap is that slight differences in operating conditions and in part geometries from build to build can create large differences in the magnitude of piston slap. In this paper we will describe a design for robustness CAE approach to eliminating piston slap. This approach considers the variations of the significant control factors in the design, e.g. piston pin offset, piston skirt design, etc. as well as the variation in the noise factors the system is subjected to, e.g. assembly clearance, skirt collapse, peak cylinder pressure, cylinder pressure rise rate, and location of peak cylinder pressure. Using analytical knowledge about how these various factors impact the generation of piston slap, a piston design for low levels of piston slap can be determined that is robust to the various noise factors.
Technical Paper

Effect of Fuel Preparation on Cold-Start Hydrocarbon Emissions from a Spark-Ignited Engine

1996-10-01
961957
Total and speciated, engine-out, hydrocarbon (HC) emissions have been measured as a function of time after a 23°C cold start of a gasoline-fueled, V-8 engine. Hydrocarbon emissions from two fuel injection systems were compared: a production port-fuel-injection (PFI) system; and a pre-vaporized (heated) central-fuel-injection (PV-CFI) system. The results indicate that, for this particular engine at the chosen operating conditions, the effect of fuel preparation on HC emissions during cold start is minimal at low load (2.57 bar IMEP (gross), MAP = 0.34 bar) but becomes significant at higher load (5.15 bar IMEP, MAP = 0.58 bar) early in the cold start. Comparison of the relative contribution to the exhaust HC of a series of fuel-derived alkanes suggests that fuel absorption in oil films is a minor contributor to HC emissions from this engine during a 23°C cold start.
Technical Paper

Predictions of In-Cylinder Tumble Flow and Combustion in SI Engines with a Quasi-Dimensional Model

1996-10-01
961962
Tumble flow has been recognized as an important and positive enhancement of combustion for SI engines. Tumble flow modeling with quasi-dimensional models is difficult because of the transient nature of tumble vortex, compared with swirl flows. Although multi-dimensional models have obtained plenty of attention recently in engine research, quasi-dimensional SI engine models will continue to dominate industrial applications in the near future. In the present research, a bulk flow model has been developed for tumble flows based on angular momentum conservation. Its effect on turbulence was then modeled using a Two-Equation Model (k-ε Model). A methodology has also been developed to use particle tracking velocimetry (PTV) measurement to calibrate the quasi-dimensional bulk flow model at engine BDC to model tumble vortex and tumble-generated turbulence. The Entrainment Combustion Model was used for combustion modeling.
Technical Paper

Effects of Injection Timing on Air-Fuel Mixing in a Direct-Injection Spark-Ignition Engine

1997-02-24
970625
Multidimensional modeling is used to study air-fuel mixing in a direct-injection spark-ignition engine. Emphasis is placed on the effects of the start of fuel injection on gas/spray interactions, wall wetting, fuel vaporization rate and air-fuel ratio distributions in this paper. It was found that the in-cylinder gas/spray interactions vary with fuel injection timing which directly impacts spray characteristics such as tip penetration and spray/wall impingement and air-fuel mixing. It was also found that, compared with a non-spray case, the mixture temperature at the end of the compression stroke decreases substantially in spray cases due to in-cylinder fuel vaporization. The computed trapped-mass and total heat-gain from the cylinder walls during the induction and compression processes were also shown to be increased in spray cases.
Technical Paper

Spectrogram Analysis of Accelerometer-Based Spark Knock Detection Waveforms

1997-05-20
972020
Spark knock pressure oscillations can be detected by a cylinder pressure transducer or by an accelerometer mounted on the engine block. Accelerometer-based detection is lower cost but is affected by extraneous mechanical vibrations and the frequency response of the engine block and accelerometer. The knock oscillation frequency changes during the expansion stroke because the chamber geometry is changing due to the piston motion and the burned gases are cooling. Spectrogram analysis shows the time-dependent frequency content of the pressure and acceleration signals, revealing characteristic signatures of knock and mechanical vibrations. Illustrative spectrograms are presented which yield physical insight into accelerometer-based knock detection.
Technical Paper

Measurements of the Effect of In-Cylinder Motion on Flame Development and Cycle-to-Cycle Variations Using an Ionization Probe Head Gasket

1997-02-24
970507
An ionization probe head gasket (to IPHG) was used to investigate flame development in a 2.0L I4 engine with two in-cylinder fluid motions. A new technique was developed to display accurate flame contours at 2%, 10% and 50% mass fraction burned crank angles using the measurements of flame arrival time from the ion probes in conjunction with cycle simulations. The flame arrival and burn rate information is used to scale the relationship between flame radius and mass fraction burned from the cycle simulation to create accurate contours of the flame for each cycle. The tumbling motion inside the combustion chamber produced by the production intake ports convected the flame towards the exhaust side of the chamber. The geometry of the flame development was relatively unaffected by changes in speed and load.
Technical Paper

Slipping Torque Converter Clutch Interface Temperature, Pressure and Torque Measurements Using Inductively Powered Radiotelemetry

1997-02-24
970679
Torque converter clutch friction interface and automatic transmission fluid (ATF) temperatures, pressure difference across the clutch piston, flow through the friction material grooves, and engine crankshaft dynamic torque were measured for typical operating conditions on a running transmission. The friction coefficient, clutch unit pressure, fraction of heat rejected to ATF flowing through the grooves, and time dependent thermal response were determined. Simplified heat transfer calculations were compared with thermal data. Clutch interface temperatures were assessed as they relate to the process of friction material and ATF degradation. The inductively powered radiotelemetry system was found to be a robust and powerful tool for investigating continuously slipping clutch system performance.
Technical Paper

In-Vehicle Engine Coolant Void Fraction and De-aeration Monitoring Using a Computerized Electrical Conductivity Method

1997-02-24
970938
Instruments and analytical techniques are described for in-vehicle monitoring of amounts of air (void fraction) in engine coolant systems and for evaluating the performance of degas reservoirs. This method, based on electrical conductivity measurements of flowing air / coolant mixture, provides measurement, acquisition and display of coolant system temperature, pressure, flow rate, instantaneous void fraction and rate of air removal by degas bottle. Embedded temperature compensation equations are used for essentially real time display of the void fraction.
Technical Paper

Commercial Van Diesel Idle Sound Quality

1997-05-20
971980
The customer's perception of diesel sounds is receiving more attention since diesel engines are being used more frequently in recent years. This paper summarizes the results of a study investigating the sound quality of diesel idle sounds in eight vans and light trucks. Subjective evaluations were conducted both in the US and the UK so that a comparison could be made. Paired comparison of annoyance and semantic differential subjective evaluation techniques were used. Correlation analysis was applied to the subjective evaluation results to determine annoying characteristics. Subjective results indicated that most annoyance rankings were similar for both the US and UK participants, with some specific differences. Correlation of objective measures to annoyance indicated a high correlation to ISO 532B loudness, dBA and kurtosis in the 1.4 kHz to 4 kHz range (aimed at quantifying the impulsiveness perception).
Technical Paper

Development of an Isolated Timing Chain Guide System Utilizing Indirect Force Measurement Techniques

1997-05-20
971963
This paper outlines the development process of a vibration isolation system for the timing chain guides of an internal combustion engine. It was determined through testing that the timing chain guides are a significant path by which the chain/sprocket impacts are transmitted to other powertrain components. These components radiate the energy as chain mesh order narrow band sound as well as wide band energy. It was found that isolation of the chain guides produced a significant reduction in radiated sound levels, reduced mesh frequency amplitudes, and improved sound quality. The development process utilized indirect force measurement techniques for simulation of the chain loading and FEA prediction of the resulting chain guide forces and displacements. The design of the isolation system involved material selection based on dynamic properties, frequency and temperature ranges, the operating environment, FEA geometry optimization, and durability testing.
Technical Paper

Exhaust Valve Seat Leakage

1997-05-01
971638
A 1.9L four cylinder engine was evaluated for leakage of cylinder charge through the exhaust valve seats. Fast FID HC analyzer traces reveal leakage. Static leakdown tests do not correlate with the Fast FID measurement, unlike previously published reports for a different engine. The causes of exhaust valve seat leakage are likely to be Flakes of cylinder deposits lodging in the valve seat Valve seat distortion due to the thermal and pressure loading of the cylinder head structure Because deposit related effects are very history dependent, it is very difficult to obtain quantitative results. Some experimental observations: Static pressure leakage measurements show variation of leakage area with cylinder pressure, caused by flexing of the valve head. Dynamic leakage results are history dependent. Leakage is reduced after running at high speed/load, and gradually build up during extended light load low speed operation.
Technical Paper

Regimes of Premixed Turbulent Combustion and Misfire Modeling in SI Engines

1998-10-19
982611
A review of flame kernel growth in SI engines and the regimes of premixed turbulent combustion showed that a misfire model based on regimes of premixed turbulent combustion was warranted[1]. The present study will further validate the misfire model and show that it has captured the dominating physics and avoided extremely complex, yet inefficient, models. Results showed that regimes of turbulent combustion could, indeed, be used for a concept-simple model to predict misfire limits in SI engines. Just as importantly, the entire regimes of premixed turbulent combustion in SI engines were also mapped out with the model.
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