Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Derivation of the Force Interaction within Strongly Coupled Systems - Application to Diesel Engine Oil Pumps

2011-05-17
2011-01-1531
Due to the increasing focus on noise and vibration for future vehicles, there is a need for a clear definition of the requirements between vehicle manufacturers and auxiliary suppliers. Auxiliary characterisations are also needed as input for structure-borne numerical prediction models. Strongly coupled systems are amongst the most difficult structure-borne noise issues, as the transmitted forces and powers are strongly dependent upon the mobilities of both the vibration source and receiver. The so-called “blocked forces” can be used as intrinsic source descriptions. The challenge is then to design auxiliary test benches perfectly rigid in the frequency range of interest. The current paper is based on the French research program MACOVAM dedicated to the vibro-acoustic characterisation of oil pumps for truck engines. An original test bench was designed to measure quasi-blocked forces over the [150 Hz-2800 Hz] frequency range.
Journal Article

Spray Formation and Combustion Analysis in an Optical Single Cylinder Engine Operating with Fresh and Aged Biodiesel

2011-04-12
2011-01-1381
The present paper describes the results of a cooperative research project between GM Powertrain Europe and Istituto Motori - CNR aimed at studying the impact of both fresh and highly oxidized RME at two levels of blending on spray formation and combustion in modern automotive diesel engines. The tests were performed on an optical single-cylinder engine sharing combustion system configuration with the 2.0L Euro5 GM diesel engine for passenger car application. Two blends (B50 and B100) blending were tested for both fresh and aged RME and compared with commercial diesel fuel in two different operating points typical of NEDC (1500rpm/2bar BMEP and 2000rpm/5bar BMEP). The experimental activity was devoted to an in-depth investigation of the spray density, breakup and penetration, mixture formation, combustion and soot formation, by means of optical techniques.
Technical Paper

Glow-plug Ignition of Ethanol Fuels under Diesel Engine Relevant Thermodynamic Conditions

2011-04-12
2011-01-1391
The requirement of reducing worldwide CO₂ emissions and engine pollutants are demanding an increased use of bio-fuels. Ethanol with its established production technology can contribute to this goal. However, due to its resistive auto-ignition behavior the use of ethanol-based fuels is limited to the spark-ignited gasoline combustion process. For application to the compression-ignited diesel combustion process advanced ignition systems are required. In general, ethanol offers a significant potential to improve the soot emission behavior of the diesel engine due to its oxygen content and its enhanced evaporation behavior. In this contribution the ignition behavior of ethanol and mixtures with high ethanol content is investigated in combination with advanced ignition systems with ceramic glow-plugs under diesel engine relevant thermodynamic conditions in a high pressure and temperature vessel.
Journal Article

The Combined Effect of HCHO and C2H4 Addition on Combustion in an Optically Accessible Diesel Engine Fueled with JP-8

2011-04-12
2011-01-1392
Misfiring or partial combustion during diesel engine operation results in the production of partial oxidation products such as ethylene (C₂H₄), carbon monoxide and aldehydes, in particular formaldehyde (HCHO). These compounds remain in the cylinder as residual gases to participate in the following engine cycle. Carbon monoxide and formaldehyde have been shown to exhibit a dual nature, retarding ignition in one temperature regime, yet decreasing ignition delay periods of hydrocarbon mixtures as temperatures exceed 1000°K. Largely unknown is the synergistic effects of such species. In this work, varying amounts of C₂H₄ and HCHO are added to the intake air of a naturally aspirated optical diesel engine and their combined effect on autoignition and subsequent combustion is examined. To observe the effect of these dopants on the low-temperature heat release (LTHR), ultraviolet chemiluminescent images are recorded using intensified CCD cameras.
Technical Paper

Spray Combustion of Biodiesel and Diesel in a Constant Volume Combustion Chamber

2011-04-12
2011-01-1380
This paper investigates the combustion of biodiesel and diesel in an optical accessible constant volume chamber that can simulate the conditions in compression ignition engines. The high-pressure and high-temperature environment in the chamber was generated by a controlled premixed combustion with desired content of oxygen left. A common rail and an injector with 160 degree included angle were used to deliver the fuel. Ultra low sulfur diesel (ULSD) and biodiesel from used cook oil were used in this paper. High speed imaging of natural luminosity from the flame was used to study the combustion flame in a time resolved manner. A combination of high speed and intensified imaging of OH chemiluminescence was employed to identify reaction zones. This method has the advantage of capturing the global pictures, thus allowing the studying of jet-to-jet variations, while it does not sacrifice the time-resolved resolution.
Journal Article

VOLTEC Battery System for Electric Vehicle with Extended Range

2011-04-12
2011-01-1373
Mid 2006 a study group at General Motors developed the concept for the electric vehicle with extended range (EREV),. The electric propulsion system should receive the electrical energy from a rechargeable energy storage system (RESS) and/or an auxiliary power unit (APU) which could either be a hydrogen fuel cell or an internal combustion engine (ICE) driven generator. The study result was the Chevrolet VOLT concept car in the North American Auto Show in Detroit in 2007. The paper describes the requirements, concepts, development and the performance of the battery used as RESS for the ICE type VOLTEC propulsion system version of the Chevrolet Volt. The key requirement for the RESS is to provide energy to drive an electric vehicle with “no compromised performance” for 40 miles. Extended Range Mode allows for this experience to continue beyond 40 miles.
Technical Paper

Stochastic Knock Detection Model for Spark Ignited Engines

2011-04-12
2011-01-1421
This paper presents the development of a Stochastic Knock Detection (SKD) method for combustion knock detection in a spark-ignition engine using a model based design approach. The SKD set consists of a Knock Signal Simulator (KSS) as the plant model for the engine and a Knock Detection Module (KDM). The KSS as the plant model for the engine generates cycle-to-cycle accelerometer knock intensities following a stochastic approach with intensities that are generated using a Monte Carlo method from a lognormal distribution whose parameters have been predetermined from engine tests and dependent upon spark-timing, engine speed and load. The lognormal distribution has been shown to be a good approximation to the distribution of measured knock intensities over a range of engine conditions and spark-timings for multiple engines in previous studies.
Technical Paper

A Study on the Mechanism of Engine Oil Consumption- Oil Upwards Transport via Piston Oil Ring Gap -

2011-04-12
2011-01-1402
Reduction of oil consumption of engines is required to avoid a negative effect on engine after treatment devices. Engines are required fuel economy for reduction of carbon-dioxide emission, and it is known that reduction of piston frictions is effective on fuel economy. However friction reduction of pistons sometimes causes an increase in engine oil consumption. Therefore reduction of engine oil consumption becomes important subject recently. The ultimate goal of this study is developing the estimation method of oil consumption, and the mechanism of oil upward transport at oil ring gap was investigated in this paper. Oil pressure under the oil ring lower rail was measured by newly developed apparatus. It was found that the piston slap motion and piston up and down motion affected oil pressure rise under the oil ring and oil was spouted through ring-gap by the pressure. The effect of the piston design on the oil pressure generation was also investigated.
Technical Paper

Frictional Characteristics of Ultrasonically Measured Lubricant Films in a Simulated Piston Ring Liner Contact

2011-04-12
2011-01-1400
An essential part of the total parasitic loss in an IC engine is due to the piston ring and liner friction. In this work, a piston ring-liner reciprocating test rig combined with ultrasonic film thickness measurement system was used to understand frictional characteristic of the lubricant that formed in the contact. Two test procedures were carried out for two lubricants with different viscosities. These procedures were a step load increment at a constant speed and a step speed increment at a constant load. The results showed that the piston ring-liner contact was in boundary lubrication regime for low operating speeds at high load. This was consistent with the oil film thickness data. However, mixed lubrication regime was observed for high operating speeds at low loads. The lubricant film thicknesses increased with speed and decreased with load.
Journal Article

Investigation into Light Duty Dieseline Fuelled Partially-Premixed Compression Ignition Engine

2011-04-12
2011-01-1411
Conventional diesel-fuelled Partially Premixed Compression Ignition (PPCI) engines have been investigated by many researchers previously. However, the ease of ignition and difficulty of vaporization of diesel fuel make it imperfect for PPCI combustion. In this study, dieseline (blending of diesel and gasoline) was looked into as the Partially Premixed Compression Ignition fuel for its combination of two fuel properties, ignition-delay-increasing characteristics and higher volatility, which make it more suitable for PPCI combustion compared to neat diesel. A series of tests were carried out on a Euro IV light-duty common-rail diesel engine, and different engine modes, from low speed/load to middle speed/load were all tested, under which fuel blend ratios, EGR rates, injection timings and quantities were varied. The emissions, fuel consumption and combustion stability of this dieseline-fuelled PPCI combustion were all investigated.
Technical Paper

Knock Detection and Estimation Based on Heat Release Strategies

2011-04-12
2011-01-1409
Engine knock has been studied extensively over the years. Its undesired effects on drivability, its potential to damage an engine, and its impact on limiting the compression ratio are the main reasons why it remains a current topic of research. This paper focuses on exploiting the connection between auto-ignition and knock. A new method based on the frequency analysis of the heat release traces is proposed to detect and estimate auto-ignition/knock robustly. Filtering the heat release signal with the appropriate bandwidth is crucial to avoid misdetection. The filter settings used in this paper are found using spectral analysis of the heat release signal. By using the proposed method, it is possible to detect auto-ignition/knock even under the presence of undesired sensor resonance effects and noise from mechanical and electrical sources.
Technical Paper

Use of Exhaust Valve Timing Advance for High Natural Gas Utilization in Low-Load Diesel Dual Fuel Operation

2011-08-30
2011-01-1767
The current study examined diesel dual fuel (DDF) operations in a four-cylinder turbocharged diesel engine under low load conditions. Experiments were performed to investigate effects of diesel injection timings and exhaust valve timing advance for DDF operations under high levels of natural gas utilization. Results showed that diesel injection timings played an important role in DDF combustion. Increasing the ratio of natural gas to total fuel resulted in greater amounts of HC and CO emissions. Advancing the exhaust valve timing increased the internal EGR, raised the in-cylinder temperature at IVC, and improved the combustion efficiency. To maximize the ratio of natural gas to total fuel, a combination of proper exhaust valve timing advance and a tuned timing of diesel injection should be employed to avoid excessive HC and CO emissions.
Journal Article

Analysis of Piston Friction - Effects of Cylinder Bore Temperature Distribution and Oil Temperature

2011-08-30
2011-01-1746
Hybrid vehicles (HVs) are becoming more widely used. Since HVs supplement engine drive with motor power, the lubricant oil temperature remains at a lower level than in a conventional gasoline vehicle. This study analyzed the effect of cylinder bore temperature and lubricant oil temperature on engine friction. The results showed that, although the lubricant oil temperature was not relevant, the bore temperature had significant effect on piston friction. It was found that raising the temperature of the middle section of the cylinder bore was the most effective way of reducing piston friction.
Technical Paper

An Analysis of Trends in Vehicle Technologies Based on Alternative Fuels: Battery Electric Vehicles and Fuel Cell Electric Vehicles

2011-08-30
2011-01-1743
The burgeoning energy and environmental crisis calls for a pressing need to develop alternative fuels which can replace fossil fuels in the near future. This paper enlists and reviews various vehicle programs based on alternative fuels, focusing mainly on battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs). Firstly we state prominent vehicle programs undertaken by different manufacturers worldwide in BEVs and FCEVs. This is followed by a comparison of vehicle specifications and features highlighting the evident improvements in their utility that have followed with time. A comprehensive analysis of the observed technological trends in the last two decades has been conducted by us. We discuss the patterns of development in the pivotal areas of BEV technology i.e. the battery and the motor in detail.
Journal Article

Smoothing HCCI Heat Release with Vaporization-Cooling-Induced Thermal Stratification using Ethanol

2011-08-30
2011-01-1760
Ethanol and ethanol/gasoline blends are being widely considered as alternative fuels for light-duty automotive applications. At the same time, HCCI combustion has the potential to provide high efficiency and ultra-low exhaust emissions. However, the application of HCCI is typically limited to low and moderate loads because of unacceptably high heat-release rates (HRR) at higher fueling rates. This work investigates the potential of lowering the HCCI HRR at high loads by using partial fuel stratification to increase the in-cylinder thermal stratification. This strategy is based on ethanol's high heat of vaporization combined with its true single-stage ignition characteristics. Using partial fuel stratification, the strong fuel-vaporization cooling produces thermal stratification due to variations in the amount of fuel vaporization in different parts of the combustion chamber.
Journal Article

The Prediction of Fuel Sloshing Noise Based on Fluid-Structure Interaction Analysis

2011-05-17
2011-01-1695
Fuel sloshing noise is involved with flow motion inside fuel tanks as well as structural characteristics of vehicles. Therefore it is necessary to introduce Fluid-Structure Interaction (FSI) analysis to predict sloshing noise phenomena more accurately. Purposes of this paper are to verify the reliability of the FSI method and suggest new CAE analysis processes to predict fuel sloshing noise. The vibration of floor panels induced by sloshing impact is evaluated through FSI analysis. A series of tests is carried out to validate simulation results. The numerical optimization of parameters is also carried out to reduce computation time. In addition, effects of sloshing noise factors are discussed based on simulation and test results. Lastly, a method to predict fuel sloshing noise by exerting sloshing load on a vehicle is suggested.
Technical Paper

Microkinetic Modelling for Propane Oxidation in Channel Flows of a Silver-Based Automotive Catalytic Converter

2011-08-30
2011-01-2094
Computational Fluid Dynamics (CFD) is used to simulate chemical reactions and transport phenomena occurring in a single channel of a honeycomb-type automotive catalytic converter under lean burn combustion. Microkinetic analysis is adopted to develop a detailed elementary reaction mechanism for propane oxidation on a silver catalyst. Activation energies are calculated based on the theory of the Unity Bond Index-Quadratic Exponential Potential (UBI-QEP) method. The order-of-magnitude of the pre-exponential factors is obtained from Transition State Theory (TST). Sensitivity analysis is applied to identify the important elementary steps and refine the pre-exponential factors of these reactions. These pre-exponential factors depend on inlet temperatures and propane concentration; therefore optimised pre-exponential factors are written in polynomial forms. The results of numerical simulations are validated by comparison with experimental data.
Technical Paper

Effect of Hydrotreated Vegetable Oil (HVO) on Particulate Filters of Diesel Cars

2011-08-30
2011-01-2096
When a new type of fuel is introduced, it is necessary to ensure that exhaust gas aftertreatment systems work properly with these fuels. Today diesel particulate filter (DPF) is an inherent part of current diesel engine's exhaust gas aftertreatment system due to stringent exhaust emission limits. The functioning of DPF depends on the composition of soot particulates of exhaust gas, whereas the type of soot depends on the fuel used. To avoid clogging, DPF has to be regenerated regularly. This regeneration is usually increasing fuel consumption, so the longer the regeneration interval is, the better is fuel economy. Fuel quality and engine-out particulate emissions are important factors affecting to the need of regeneration. Renewable fuels burn cleanly and produce less particulate emissions than ordinary diesel fuel. Therefore, the increase of exhaust backpressure is slower enabling longer regeneration frequency.
Technical Paper

Experimental Investigation of Applying Raw Fuel Injection Technique for Reducing Methane in Aftertreatment of Diesel Dual Fuel Engines Operating under Medium Load Conditions

2011-08-30
2011-01-2093
Towards the effort of using natural gas as an alternative fuel for a diesel engine, the concept of Diesel Dual Fuel (DDF) engine has been shown as a strong candidate. Typically, DDF's engine-out emission species such as soot and nitrogen oxides are decreased while carbon monoxide and hydrocarbons are increased. The aftertreatment system is required in order to reduce these pollutant emissions from DDF engines. Additionally, DDF engine exhaust has a wide temperature span and is rich in oxygen, which makes HC emissions, especially methane (CH₄), difficult to treat. Until now, it is widely accepted that the key parameter influencing methane oxidation in a catalytic converter is high exhaust temperature. However, a comprehensive understanding of what variables in real DDF engine exhausts most influencing a catalytic converter performance are yet to be explored.
Journal Article

Additive Formulation Technology for Fuel Economy Passenger Car Motor Oil and Development of Sequence VID Screener

2011-08-30
2011-01-2111
Fuel economy is one of the most essential performance requirements for Passenger Car Motor Oil because of fuel economy regulations in many countries and increasing fuel prices. The ILSAC GF-5 specification was issued on December 22, 2009 and requires better fuel economy performance based on the Sequence VID (Seq. VID) Test and higher weighted piston deposit merits based on the Sequence IIIG Test, compared to the ILSAC GF-4 specification. Fuel economy performance is affected by viscosity, friction modification and the lubricant additive chemistries. However, fuel economy engine tests under combustion mode introduce high variability into a fuel economy measurement. Screening by bench testing is complicated by the difficulty to reproduce friction conditions of all of engine parts. A motored friction torque test using an engine is one of the better solutions for fuel economy screening.
X