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Technical Paper

Trends and Forecasts for Turbocharging

1988-03-01
871147
Predictable and unpredictable forces will change the direction of the charge-air systems industry. The driver of diesel engine development will be the stringent emissions regulations of the 1990s. The drivers in the gasoline engine market will be improved fuel economy, performance, durability and emissions. Forces will also influence the charge-air marketplace, including changes in emission standards, national fiscal policies, political issues, fuel prices, alternate fuels and consumer tastes. The world community mandate for engines that are clean, quiet, durable and fuel efficient will be satisfied, increasingly, by first-tier component suppliers developing integrated systems solutions.
Technical Paper

Application of Specialized FEA Dynamic Modeling Techniques for Noise Reduction of Superchargers

1999-05-17
1999-01-1718
A simulation methodology for dynamic modeling of geared rotor systems such as superchargers was used for determining the housing vibration response. The approach provides an ability to make quick parametric design modifications to the model for evaluation of relative noise response with the assumption that the averaged housing vibration level correlates approximately to the noise radiating from the surface. The housing in some cases was modeled as a lumped mass representation for efficiency, and when higher accuracy of housing modes was needed, a detailed flexible Finite Element Analysis (FEA) representation was used. The interesting features of the methodology were the use of constraint equations to model the gear mesh response per unit Transmission Error (TE) input, along with summarizing the component kinetic and strain energy for each mode and the mesh compliance for fast evaluation of opportunities for noise reduction.
Technical Paper

Reconstruction of the Cylinder Pressure from Vibration Measurements for Prediction of Exhaust and Noise Emissions in Ethanol Engines

1999-05-17
1999-01-1658
There are growing demands for condition monitoring of IC engines, and therefore any method in order to improve the performance of the engines ought to be evaluated. This paper proposes a new approach for the prediction and optimisation of noise and exhaust emissions in IC engines. The idea is to reconstruct the cylinder pressure from vibration measurements on the engine surface by using the complex cepstrum method [3, 4]. The reconstructed cylinder pressure is further used as input in Multivariate models, based on cylinder pressure, for estimating noise and exhaust emissions. This paper demonstrates the applicability of the method for modelling of noise and exhaust emissions
Technical Paper

Considerations About Chaotic Dynamics of Exhaust Tube and its Design Optimization in Respect to its Dynamic Properties

1999-05-17
1999-01-1657
Vibration of an exhaust tube with a non-linear fixing construction is analyzed. Numerical and laser holography investigation methods are used for the determination of vibration processes happening nearby the cylinder fixing areas. Obviously, the analyzed non-linear system can produce complex reactions even to harmonic excitations. The knowledge about such zones of “wrong” dynamic behavior may help to eliminate and reduce higher noise levels and extend the lifetime of the construction.
Technical Paper

On the Influence of Manifold Geometry on Exhaust Noise

1999-05-17
1999-01-1650
The influence of manifold geometry on exhaust noise is studied. First, a linear description of the problem is presented, so that potential relevant factors may be identified. Then a full non-linear simulation is performed, for a simple geometry, in order to check, in more realistic conditions, the ideas obtained from the linear theory. The results indicate that, although some qualitative trends may be obtained from the linear analysis, the role of back-reaction of the manifold on the engine (a non-linear coupling effect) may be determinant.
Technical Paper

Effect of High Squish Combustion Chamber on Simultaneous Reduction of NOx and Particulate from a Direct-Injection Diesel Engine

1999-05-03
1999-01-1502
In this study it is tried to reduce NOx and particulate emissions simultaneously in a direct injection diesel engine based on the concept of two-stage combustion. At initial combustion stage, NOx emission is reduced with fuel rich combustion. At diffusion combustion stage, particulate emission is reduced with high turbulence combustion. The high squish combustion chamber with reduced throat diameter is used to realize two-stage combustion. This combustion chamber is designed to produce strong squish that causes high turbulence. When throat diameter of the high squish combustion chamber is reduced to some extent, simultaneous reduction of NOx and particulate emissions is achieved with less deterioration of fuel consumption at retarded injection timing. Further reduction of NOx emission is realized by reducing the cavity volume of the high squish combustion chamber. Analysis by endoscopic high speed photography and CFD calculation describes the experimental results.
Technical Paper

A Photographic Investigation of Multi-Stage Fuel Injection in a Single Cylinder DI Diesel Engine

1999-05-03
1999-01-1501
Increasing concern about the impact of internal combustion engines on the environment has led to ever more stringent emission legislation, and the introduction of more sophisticated equipment to enable the requirements to be achieved. One way of improving the emissions from direct injection (DI) diesel engines is to use multi-stage fuel injection, and an investigation performed on such a system is reported in this paper. In this case, the multi-stage fuel injector caused an increase in the exhaust smoke at low load, and an in-cylinder photographic technique was used to examine why this occurred. A multi-stage fuel injector with a VCO nozzle was fitted to a small, high-speed, direct injection diesel engine fitted with a transparent piston for optical access. The combustion process was filmed using a high-speed 16 mm cine camera, and the fuel injection process was illuminated by a high power, copper-vapour laser.
Technical Paper

A Comparison of Gasoline Direct Injection and Port Fuel Injection Vehicles: Part II - Lubricant Oil Performance and Engine Wear

1999-05-03
1999-01-1499
Four 1998 Mitsubishi Carismas, two equipped with direct injection (GDI) and two with port fuel injection engines (PFI) were tested in a designed experiment to determine the effect of mileage accumulation cycle, engine type, fuel and lubricant type on engine wear and engine oil performance parameters. Fuel types were represented by an unadditised base fuel meeting EEC year 2000 specifications and the same base fuel plus synthetic deposit control additive packages. Crankcase oils were represented by two types (1) a 5W-30 API SJ/ILSAC GF-2 type engine oil and (2) a 10W-40 API SH/CF ACEA A3/ B3-96 engine oil. The program showed that specific selection of oil additive chemistry may reduce formation of intake valve deposits in GDI cars.. In general, G-DI engines produced more soot and more pentane insolubles and were found to be more prone to what appears to be soot induced wear than PFI engines.
Technical Paper

What Fuel Economy Improvement Technologies Could Aid the Competitiveness of Light-Duty Natural Gas Vehicles?

1999-05-03
1999-01-1511
The question of whether increasing the fuel economy of light-duty natural gas fueled vehicles can improve their economic competitiveness in the U.S. market, and help the US Department of Energy meet stated goals for such vehicles is explored. Key trade-offs concerning costs, exhaust emissions and other issues are presented for a number of possible advanced engine designs. Projections of fuel economy improvements for a wide range of lean-burn engine technologies have been developed. It appears that compression ignition technologies can give the best potential fuel economy, but are less competitive for light-duty vehicles due to high engine cost. Lean-burn spark ignition technologies are more applicable to light-duty vehicles due to lower overall cost. Meeting Ultra-Low Emission Vehicle standards with efficient lean-burn natural gas engines is a key challenge.
Technical Paper

In-Use Emissions from Natural Gas Fueled Heavy-Duty Vehicles

1999-05-03
1999-01-1507
The objective of the work described here is to test the performance of closed-loop controlled, heavy-duty CNG engines in-use, on fuels of different methane content; and to compare their performance with similar diesel vehicles. Performance is measured in terms of pollutant emissions, fuel economy, and driveability. To achieve this objective, three buses powered by closed-loop controlled, dedicated natural gas engines were tested on the heavy-duty chassis dynamometer facility at the Colorado Institute for Fuels and High Altitude Engine Research (CIFER). Emissions of regulated pollutants (CO, NOx, PM, and THC or NMHC), as well as emissions of alde-hydes for some vehicles, are reported. Two fuels were employed: a high methane fuel (90%) and a low methane fuel (85%). It was found that the NOx, CO, and PM emissions for a given cycle and vehicle are essentially constant for different methane content fuels.
Technical Paper

A Model For Estimating Oil Vaporization From The Cylinder Liner As A Contributing Mechanism to Engine Oil Consumption

1999-05-03
1999-01-1520
A model has been developed for estimating the oil vaporization rate from the cylinder liner of a reciprocating engine. The model uses input from an external cycle simulator and an external liner oil film thickness model. It allows for the change in oil composition and the change in oil film thickness due to vaporization. It also estimates how the passage of the compression and scraper rings combine with the vaporization to influence the steady-state composition of the oil layer in the upper ring pack. Computer model results are presented for a compression-ignition engine using a range of liner temperatures, several engine speeds, and two different oils. Vaporization is found to be highly dependent on liner temperature and steady-state oil composition. The steady-state oil composition near the top of the cylinder is found to be significantly different than the composition of the oil near the bottom of the cylinder.
Technical Paper

A Study on Engine Bearing Wear and Fatigue Using EHL Analysis and Experimental Analysis

1999-05-03
1999-01-1514
The possibility of predicting engine bearing durability by elastohydrodynamic lubrication (EHL) calculations was investigated with the aim of being able to improve durability efficiently without conducting numerous confirmation tests. This study focused on the connecting rod big-end bearing of an automotive engine. The mechanisms of wear and fatigue, which determine bearing durability, were estimated by comparing the results of EHL analysis and experimental data. This comparison showed the possibility of predicting the wear amount and the occurrence of fatigue by calculation.
Technical Paper

Effects of Injection Timing and Fuel Properties on Exhaust Odor in DI Diesel Engines

1999-05-03
1999-01-1531
Exhaust odor of DI diesel engines is worse than that of gasoline engines, especially at low temperatures and at idling. As the number of passenger cars with DI diesel engines is increasing worldwide because of their low CO2 emissions, odor reduction research of DI diesel engines is important. Incomplete combustion is a major cause of exhaust odor. Generally, odor worsens due to overleaning of the mixture in the cylinder and due to fuel adhering on the combustion chamber walls. To confirm this, the influences of different engine running conditions and fuel properties were investigated. The reason for the changes in exhaust odor with injection timing is evaluated by considerations of optimum positions of the maximum heat release. With n-heptane, a low boiling point fuel, odorous emissions increase because of overleaning of the mixture.
Technical Paper

Development of Improved Arctic Engine Oil (OEA-30)

1999-05-03
1999-01-1523
U.S. Army arctic engine oil, MIL-L-46167B, designated OEA, provides excellent low-temperature operation and is multi functional. It is suitable for crankcase lubrication of reciprocating internal combustion engines and for power-transmission fluid applications in ground equipment. However, this product required 22-percent derated conditions in the two-cycle diesel engine qualifications test. Overall, OEA oil was limited to a maximum ambient temperature use of 5°C for crankcase applications. The technical feasibility of developing an improved, multi functional arctic engine oil for U.S. military ground mobility equipment was investigated. The concept was proven feasible, and the new oil, designated as OEA-30, has exceptional two-cycle diesel engine performance at full engine output and can be operated beyond the 5°C maximum ambient temperature limit of the MIL-L-46167B product.
Technical Paper

The Optimum Design for Frictional Surface of Piston Ring of Engines

1999-05-03
1999-01-1526
Based on the principle of conjugate curve surface and the theory of hydrodynamic lubrication, the similar spherical spiral surface, which has the best lubrication effect, was obtained in the paper. Experiment show, this kind of frictional surface is lower 15% at power loss, and it is higher 13% at service life than the traditional frictional surface of piston ring, (such as barrel, stepped, cuneiform, rectangle and so on).
Technical Paper

Emissions and Fuel Economy of a 1998 Toyota with a Direct Injection Spark Ignition Engine

1999-05-03
1999-01-1527
A 1998 Toyota Corona passenger car with a direct injection spark ignition (DISI) engine was tested via a variety of driving cycles using California Phase 2 reformulated gasoline. A comparable PFI vehicle was also evaluated. The standard driving cycles examined were the Federal Test Procedure (FTP), Highway Fuel Economy Test, US06, simulated SC03, Japanese 10-15, New York City Cycle, and European ECE+EDU. Engine-out and tailpipe emissions of gas phase species were measured each second. Hydrocarbon speciations were performed for each phase of the FTP for both the engine-out and tailpipe emissions. Tailpipe particulate mass emissions were also measured. The results are analyzed to identify the emissions challenges facing the DISI engine and the factors that contribute to the particulates, NOx, and hydrocarbon emissions problems of the DISI engine.
Technical Paper

Two-Dimensional In-Cylinder Flow Field in a Natural Gas Fueled Spark Ignition Engine Probed by Particle Tracking Velocimetry and Its Dependence on Engine Specifications

1999-05-03
1999-01-1534
An experimental study was made to investigate in-cylinder flow field in a natural gas fueled spark ignition engine and the effects of engine specifications on in-cylinder flow field. The instantaneous two-dimentional flow fields in a single-cylinder visualization engine, which has 75mm bore and 62mm stroke, were measured in various cross sections perpendicular to the cylinder axis by using the laser light sheet PTV method at various crank angles during intake, compression, and expansion strokes over the wide range of piston combustion chamber configuration, top clearance, and nominal swirl ratio. Flow fields during compression and expansion strokes were also calculated using KIVA2 simulation code for better understanding of the measured results. The results showed that induction-generated swirl is getting concentric to the cylinder center in compression stroke, and is shifted in the radial direction in expansion stroke.
Technical Paper

Gas Flows Through the Inter-Ring Crevice and Their Influence on UHC Emissions

1999-05-03
1999-01-1533
Influence of the inter-ring crevice, the volume between the top and second piston rings, on unburned hydrocarbon (UHC) emission was experimentally and numerically investigated. The ultimate goal of this study was to estimate the level of UHC emission induced by the blow-up of inter-ring mixture, i.e., unburned gases trapped in the inter-ring crevice. In the experiments, the inter-ring mixture was extracted to the crankcase during the late period of expansion and the early period of exhaust stroke through the engraved grooves on the lower part of cylinder wall. Extraction of the mixture resulted in the significant reductions of UHC emission in proportion to the increments of blowby flow rate, without any losses in efficiency and power. This experimental study has confirmed the importance of inter-ring crevice on UHC emission in an SI engine and established a relationship between the inter-ring mixture and UHC emission.
Technical Paper

Effects of Fuel Properties on Combustion and Emission Characteristics of a Direct-Injection Diesel Engine

2000-06-19
2000-01-1851
This study investigates the effects of fuel properties on combustion characteristics and emissions such as NOx, smoke, THC and particulates in a direct-injection diesel engine. Fuel properties, such as cetane number and aromatic content, are varied independently in the experiments to separate their effects. The engine tests are carried out at steady operation with changed load, injection timing and injection pressure. The results show that reducing cetane number results in the increase of NOx and decrease of particulate emission at high load. This is because the low cetane number fuel has the long ignition delay and causes the high maximum heat release rate and the short combustion duration. However, high THC emission is produced at low load for the low cetane number fuel.
Technical Paper

EC-Diesel Technology Validation Program Interim Report

2000-06-19
2000-01-1854
ARCO has developed diesel fuel called Emission Control Diesel (EC-D) that results in substantially lower exhaust emissions compared to a typical California diesel fuel. EC-D has ultra-low sulfur content, low aromatics, and has a high cetane number. EC-D is produced from typical crude oil using a conventional refining process. Initial engine laboratory tests and vehicle tests indicated that EC-D reduced regulated emissions while maintaining fuel economy, compared to a typical California diesel fuel. Ultra-low sulfur diesel fuels such as EC-D may enable the widespread use of passive catalyzed particulate filters for both new and existing diesel engines. The use of catalyzed particulate filters could allow large reductions of particulate matter emitted from vehicles. A one-year technology validation program is being run to evaluate EC-D and catalyzed particulate filters using diesel vehicles operating in Southern California.
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