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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.
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

Investigations of the impact of 10% ethanol blended fuels on performances of sold gasoline vehicles in the Japanese market already on the road in Japan

2011-08-30
2011-01-1987
The study of 10% ethanol blended gasoline (E10 gasoline) utilization has been conducted in the Japan Auto-Oil Program (JATOP). In order to clarify the impact of E10 gasoline on vehicle performances, exhaust emissions, evaporative emissions, driveability and material compatibility have been investigated by using domestic gasoline vehicles including mini motor vehicles which are particular to Japan. The test results reveal that E10 gasoline has no impact on exhaust emissions, engine startup time and acceleration period under the hot start condition, but a slight deterioration is observed in some test cases under the cold start condition using E10 gasolines with 50% distillation temperature (T50) level set to the upper limit of Japanese Industrial Standards (JIS) K 2202. Regarding evaporative emissions, the tested vehicles shows no remarkable increase in the hot soak loss (HSL), diurnal breathing loss (DBL) and running loss (RL) testing with E10 gasolines.
Technical Paper

Determination Of Mixture Of Methanol And Ethanol Blends In Gasoline Fuels Using A Miniaturized NIR Flex Fuel Sensor

2011-08-30
2011-01-1988
Based on their 25 world-wide years experience in refining and fuel formulation using Near Infrared technology, the SP3H team has developed an innovative and miniaturized optical fuel quality sensor. The sensor output is based on an HCP matrix (HydroCarbon Profilers) and provides information on the fine chemistry of fuels such as aromatics, olefins, isoparaffins and oxygenates content and information related to the lengths of the Carbon-Carbon Chain. The goal of this study is to answer the need for new flex-fuel sensors able to provide the rate and the type of oxygenates used in different mixtures of binary and ternary blends of methanol, ethanol and gasoline for the emerging markets. This paper presents the results of the models and the accuracy of the optical sensor for the determination and prediction of Methanol-Ethanol-gasoline mixtures based on the HCP approach.
Journal Article

Butanol Blending - a Promising Approach to Enhance the Thermodynamic Potential of Gasoline - Part 1

2011-08-30
2011-01-1990
Blending gasoline with oxygenates like ethanol, MTBE or ETBE has a proven potential to increase the thermodynamic efficiency by enhancing knock resistance. The present research focuses on assessing the capability of a 2- and tert-butanol mixture as a possible alternative to state-of-the-art oxygenates. The butanol mixture was blended into a non-oxygenated reference gasoline with a research octane number (RON) of 97. The butanol blending ratios were 15% and 30% by mass. Both the thermodynamic potential and the impact on emissions were investigated. Tests are performed on a highly boosted single-cylinder gasoline engine with high load capability and a direct injecting fuel system using a solenoid-actuated multi-hole injector. The engine is equipped with both intake and exhaust cam phasers. The engine has been chosen for the fuel investigation, as it represents the SI technology with a strongly increasing market share.
Journal Article

Effects of Ethanol Content on Gasohol PFI Engine Wide-Open-Throttle Operation

2009-06-15
2009-01-1907
The NOx emission and knock characteristics of a PFI engine operating on ethanol/gasoline mixtures were assessed at 1500 and 2000 rpm with λ =1 under Wide-Open-Throttle condition. There was no significant charge cooling due to fuel evaporation. The decrease in NOx emission and exhaust temperature could be explained by the change in adiabatic flame temperature of the mixture. The fuel knock resistance improved significantly with the gasohol so that ignition could be timed at a value much closer or at MBT timing. Changing from 0% to 100% ethanol in the fuel, this combustion phasing improvement led to a 20% increase in NIMEP and 8 percentage points in fuel conversion efficiency at 1500 rpm. At 2000 rpm, where knocking was less severe, the improvement was about half (10% increase in NIMEP and 4 percentage points in fuel conversion efficiency).
Journal Article

Development of a Direct Injection High Efficiency Liquid Phase LPG Spark Ignition Engine

2009-06-15
2009-01-1881
Direct Injection (DI) is believed to be one of the key strategies for maximizing the thermal efficiency of Spark Ignition (SI) engines and meet the ever-tightening emissions regulations. This paper explores the use of Liquefied Petroleum Gas (LPG) liquid phase fuel in a 1.5 liter SI four cylinder gasoline engine with double over head camshafts, four valves per cylinder, and centrally located DI injector. The DI injector is a high pressure, fast actuating injector enabling precise multiple injections of the finely atomized fuel sprays. With DI technology, the injection timing can be set to avoid fuel bypassing the engine during valve overlap into the exhaust system prior to combustion. The fuel vaporization associated with DI reduces combustion chamber and charge temperatures, thereby reducing the tendency for knocking. Fuel atomization quality supports an efficient combustion process.
Technical Paper

Simulation of Scavenging Process, Internal Mixture Preparation, and Combustion of a Gasoline Direct Injection Two-Cylinder Two-Stroke Engine

2009-11-03
2009-32-0046
The continuous improvement of the numerical methods together with the increase of computer power allows the simulation of more and more complex technical problems even for increasing calculation domains. In order to get effective and significant results for the two-stroke two-cylinder engine, the simulation of the complete geometry with both cylinders and the complete exhaust port is required. However, the simulation requires several revolutions until the gas dynamic inside the exhaust port achieves a steady state. Hence, the simulation of a two-cylinder two-stroke engine consumes a lot of calculation time; nevertheless it is still acceptable in the development process of a new engine. This paper covers the discussion of the simulation of a two-stroke two-cylinder high-performance engine using the commercial CFD Code Fluent 6.3.26. The used settings for the simulation, like the turbulence model, injection settings, combustion model and reduced reaction mechanism are presented.
Technical Paper

Spark ignition and spark-assisted controlled auto-ignition in an optical gasoline engine

2009-11-03
2009-32-0072
The results of an experimental study of the low speed and low load operation of an optical research engine are presented for spark-ignition (SI) and spark-assisted, controlled auto-ignition (SA-CAI). A direct injection gasoline engine was modified for optical access into the combustion chamber. At 1000 rpm and 3 bar NIMEP, stable SA-CAI combustion was achieved with predicted EGR rates in excess of 45%. The coefficient of variation (CoV) in NIMEP was 4.8% compared to 6.5% recorded in the SI case, with no EGR. Particle image velocimetry measurements of the airflow showed lower mean and turbulent velocities in the SA-CAI case at the end of the compression stroke. Planar Laser Induced Fluorescence (PLIF) measurements of the fuel vapour signal in the air-fuel-residual distribution were significantly lower than in the SI case. Indicating analysis showed that the main combustion burn duration was considerably greater in the SA-CAI case.
Technical Paper

Knocking Investigations in a small Two-Stroke SI Engine

2009-11-03
2009-32-0013
The trend of higher specific power and increased volumetric efficiency leads to unwanted combustion phenomenon such as knocking, pre-ignition and self-ignition. For four-stroke engines, the literature reports that knocking depends, to a large extent, on the ignition angle, the degree of enrichment and the volumetric efficiency. In recent research, knock investigations in two-stroke engines have only been carried out to a limited extent. This paper discusses an investigation of the influence of various parameters on the knock characteristics of a small, high-speed, two-stroke SI engine. In particular, the degree of enrichment, the volumetric efficiency and the ignition timing serve as the parameters.
Technical Paper

Improvement of Atomization Characteristics of a Micro Nozzle Array Type Gasoline Injector

2009-12-13
2009-28-0041
Atomization characteristics of an ultrasonic fuel injector using a micro nozzle array were improved by change of horn geometries. Micro nozzles whose exit diameter d = 3 µm are mounted on a thin metal film, and the number of micro nozzles was varied from 2.0 × 104 to 1.2 × 105. Gasoline is periodically pushed out from the micro nozzles at frequencies from 62 to 65 kHz. A disk type PZT (Lead zirconium titanate) is used as an ultrasonic oscillator, and the oscillation is amplified by an axi-symmetric step-type horn. The oscillation amplitude is proportional to the area ratio of the horn. The number of micro nozzles increases with the increase in the small end diameter of the horn, while the oscillation amplitude decreases at the same time. In order to increase the fuel flow rate, the horn small end diameter Ds was varied from 10.5 to 25 mm, while the large end diameter is fixed at 30 mm.
Technical Paper

Performance and Emissions of a Spark Ignition Engine Running on Gasoline Adulterated with Kerosene

2009-12-13
2009-28-0014
Fuel adulteration is becoming a widespread problem in South Asian countries, some forms of which are responsible for deterioration in performance and increase in emissions of spark ignition (SI) engines. A common form of adulteration is to blend gasoline with kerosene which is prevalent because of financial benefit resulting from the price difference between the two fuels. In addition to rendering the fuel more knock prone, based on previous studies it can be surmised that gasoline adulteration with kerosene would increase hydrocarbon (HC), particulate matter (PM) and polycyclic aromatic hydrocarbon (PAH) emissions from SI engines. However, detailed information about the emission effects with the extent of adulterant in the fuel is lacking. This paper elaborates on the effects of kerosene adulteration starting from change in the properties of the gasoline, including volatility and enthalpy of vaporization, to combustion characteristics of gasoline-kerosene blends in an SI engine.
Technical Paper

Investigation of Performance and Emissions with Low Level Ethanol-Gasoline Blends on a Passenger Car

2009-01-21
2009-26-0034
Ethanol blended gasoline has offered new opportunities in Indian automotive industry. Ethanol (5%) blending in gasoline is already commercially implemented in many states of India. The steep increase in crude oil prices and depleting oil resources has forced the government and Oil Marketing Companies (OMC) to look forward to the implementation of 10∼20% ethanol-gasoline blend in future. Before implementation of the 10% blend, the effect of ethanol-gasoline on vehicle performance and emissions are need to be studied. This paper investigates the performance of vehicle in terms of fuel economy, cold and hot start ability, power performance and emissions performance (Type-I and IV) of gasoline passenger car with 5% and 10% ethanol-gasoline blends.
Technical Paper

Effect of Improving the Gasoline Fuel Quality on Exhaust Emissions from in-use Vehicles - An Experimental Study

2009-01-21
2009-26-0016
In India, two and three-wheelers constitute about 70% of the total in-use vehicle population and consume about 2/3rd of the total gasoline, rest of the gasoline being consumed primarily by the passenger cars. This paper presents the findings of an experimental study carried out on in-use gasoline vehicles, including two and three- wheelers and passenger cars. The gasoline fuels used for the study were equivalent to Euro-II, Euro-III and Euro-IV fuel quality specifications. The study analyzes the effect of improving the gasoline fuel quality on exhaust emissions from in-use vehicles.
Technical Paper

Optimization of the Impulsiveness Performance of a Diesel Engine

2011-05-17
2011-01-1668
The interior sound quality of passenger cars has a big impact on the perceived comfort of the vehicle. With today's direct-injection diesel engines this fact gains importance, since the customers are more and more attracted by them due to their low fuel consumption and their good driving performance. In the course of the development of diesel technology, the typical impulsive noise of diesel combustion engines (the so-called “diesel knocking”) is less and less tolerated. Furthermore, the possibilities to tune the combustion with respect to noise are nowadays more limited due to the more stringent targets for CO2 and Euro 5/6 emissions. This possibly leads to a higher risk in not fulfilling exterior and interior sound quality targets like diesel knocking noise. The diesel knocking perceived inside the vehicle is influenced by various parameters.
Technical Paper

Z-type Schlieren Setup and its Application to High-Speed Imaging of Gasoline Sprays

2011-08-30
2011-01-1981
Schlieren and shadowgraph imaging have been used for many years to identify refractive index gradients in various applications. For evaporating fuel sprays, these techniques can differentiate the boundary between spray regions and background ambient gases. Valuable information such as the penetration rate, spreading angle, spray structure, and spray pattern can be obtained using schlieren diagnostics. In this study, we present details of a z-type schlieren system setup and its application to port-fuel-injection gasoline sprays. The schlieren high-speed movies were used to obtain time histories of the spray penetration and spreading angle. Later, these global parameters were compared to specifications provided by the injector manufacturer. Also, diagnostic parameters such as the proportion of light cut-off at the focal point and the orientation of knife-edge (schlieren-stop) used to achieve the cut-off were examined.
Technical Paper

Correlation of Chemical Compositions and Fuel Properties with Fuel Octane Rating of Gasoline Containing Ethanol

2011-08-30
2011-01-1986
With increasing use of ethanol in automotive fuel in recent years, which can be made from renewable feedstocks, the chemical composition of gasoline is changed. The compositional change results in many changes in fuel properties. One key property is the octane rating of gasoline. Market data has shown the shifts of octane rating (antiknock index or AKI) upward due to more penetration of E10 gasoline in the US market. However, the increase in research octane is more pronounced as compared to motor octane, therefore the increase in octane sensitivity in gasoline. Refineries have used the change in octane due to ethanol contribution by sending so called sub-grade gasoline to terminals expecting the final blend after mixing with ethanol to meet the market requirement in octane. Thus the octane rating of the final blend will largely depend on the sub-grade gasoline composition and ethanol.
Technical Paper

Evaporation of Gasoline-Like and Ethanol-Based Fuels in Hollow-Cone Sprays Investigated by Planar Laser-Induced Fluorescence and Mie Scattering

2011-08-30
2011-01-1889
The evaporation of different fuels and fuel components in hollow-cone sprays at conditions similar to those at stratified cold start has been investigated using a combination of planar laser-induced fluorescence (LIF) and Mie scattering. Ketones of different volatility were used as fluorescent tracers for different fuel components in gasoline-like model fuels and ethanol-based fuels. LIF and Mie images were compared to evaluate to what extent various fuel components had evaporated and obtained a spatial distribution different from that of the liquid drops, as a function of fuel temperature and time after start of injection. A selective and sequential evaporation of fuel components of different volatility was found.
Technical Paper

Evaluation of a 0D Phenomenological SI Combustion Model

2011-08-30
2011-01-1894
Powerful 1D engine simulation softwares are widely used in the automotive industry to model internal combustion engines. The gas-dynamics exchange process is often well modeled whereas the combustion process is accounted for as a Wiebe function. As the combustion description is a key parameter for engine efficiency evaluation, predictive 0D modeling of heat release seems to be the issue in order to reliably model the cylinder pressure. A 0D phenomenological SI combustion model is proposed in order to predictively describe the heat release rate, this model being developed with Matlab-Simulink and coupled to GT Power. The model is based on eddy burn up approach and takes into account the geometry of the combustion chamber, the turbulent intensity, the RBG effects. As turbulence is a key feature in SI combustion modeling with eddy burn up approach, at this stage of the study turbulent kinetic energy data resulting from 3D CFD computation was employed.
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