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Viewing 1 to 30 of 11558
2010-10-25
Journal Article
2010-01-2165
David Serrano, Olivier Laget, Dominique Soleri, Stephane Richard, Benoit Douailler, Frederic Ravet, Marc Moreau, Nathalie Dioc
The introduction of alternative fuels is crucial to limit greenhouse gases. CNG is regarded as one of the most promising clean fuels given its worldwide availability, its low price and its intrinsic properties (high knocking resistance, low carbon content...). One way to optimize dedicated natural gas engines is to improve the CNG slow burning velocity compared to gasoline fuel and allow lean burn combustion mode. Besides optimization of the combustion chamber design, hydrogen addition to CNG is a promising solution to boost the combustion thanks to its fast burning rate, its wide flammability limits and its low quenching gap. This paper presents an investigation of different methane/hydrogen blends between 0% and 40 vol. % hydrogen ratio for three different combustion modes: stoichiometric, lean-burn and stoichiometric with EGR.
2010-10-25
Technical Paper
2010-01-2183
Rafael Lugo, Vahid Ebrahimian, Catherine Lefebvre, Chawki Habchi, Jean-Charles de Hemptinne
The adequacy of the fuels with the engines has been often a major goal for the oil industry or car manufacturers. As the formulation of fuels becomes more complex, the use of numerical simulation provides an efficient way to understand and analyze the combustion process. These conclusions become increasingly true with the appearance of second generation biofuels. This paper describes a methodology for the representation of fuels and biofuels using a lumping procedure combined with adequate thermodynamic and thermophysical models. This procedure allows computing different thermodynamic and thermophysical properties for simulation purposes in internal combustion engines. The lumping approach involves reducing analytical data to a few pseudo-components characterized by their molecular weight, critical properties and acentric factor.
2010-10-25
Journal Article
2010-01-2193
Peter Hottenbach, Thorsten Brands, Gerd Grünefeld, Andreas Janssen, Martin Muether, Stefan Pischinger
The finite nature and instability of fossil fuel supply has led to an increasing and enduring investigation demand of alternative and regenerative fuels. An investigation program is carried out to explore the potential of tailor made fuels to reduce engine-out emissions while maintaining engine efficiency and an acceptable noise level. In this paper, fundamental results of the Diesel engine relevant combustion are presented. To enable optimum engine performance a range of different reference fuels have been investigated. The fundamental effects of different physical and chemical properties on emission formation and engine performance are investigated using a thermodynamic diesel single cylinder research engine and an optically-accessible combustion vessel. Depending on the chain length and molecular structure, fuel compounds vary in cetane number, boiling temperature etc. Therefore, different hydrocarbons including n-heptane, n-dodecane, and l-decanol were investigated.
2010-10-25
Technical Paper
2010-01-2209
K. Dean Edwards, Robert Wagner, Thomas Briggs
Modern diesel engines used in light-duty transportation applications have peak brake thermal efficiencies in the range of 40-42% for high-load operation with substantially lower efficiencies at realistic road-load conditions. Thermodynamic energy and exergy analysis reveals that the largest losses from these engines are due to combustion irreversibility and heat loss to the coolant, through the exhaust, and by direct convection and radiation to the environment. Substantial improvement in overall engine efficiency requires reducing or recovering these losses. Unfortunately, much of the heat transfer either occurs at relatively low temperatures resulting in large entropy generation (such as in the air-charge cooler), is transferred to low-exergy flow streams (such as the oil and engine coolant), or is radiated or convected directly to the environment.
2010-09-28
Journal Article
2010-32-0016
Giovanni Ferrara, Alessandro Bellissima, Marco Doveri, Francesco Balduzzi
The purpose of this work is to perform an analysis on the modifications necessary to convert a four-stroke engine into a non-conventional two-stroke engine. The first aim of this work is to reach the theoretical advantages of the two stroke engine (high torque values at lower rpm and working regularity) and, at the same time, to avoid the usual problems of the two stroke cycle (short-circuit of fresh air-fuel mixture and consequently pollutant emissions and high specific fuel consumption). The target is to develop a small engine with innovative solutions that allows to obtain high performance coupled with good mechanical and thermodynamic efficiency. The starting base engine is a 125cc four-stroke two-valves scooter engine equipped with a volumetric compressor. The idea is to convert it from four to two stroke cycle, using head valves and adding scavenge ports in the cylinder.
2010-09-28
Technical Paper
2010-32-0035
Dalibor Jajcevic, Matthias Fitl, Stephan Schmidt, Karl Glinsner, Raimund Almbauer
The exhaust system design has an important influence on the charge mass and the composition of the charge inside the cylinder, due to its gas dynamic behavior. Therefore the exhaust system determines the characteristics of the indicated mean effective pressure as well. The knowledge of the heat transfer and the post-combustion process of fuel losses inside the exhaust system are important for the thermodynamic analysis of the working process. However, the simulation of the heat transfer over the exhaust pipe wall is time consuming, due to the demand for a transient simulation of many revolutions until a cyclic steady condition is reached. Therefore, the exhaust pipe wall temperature is set to constant in the conventional CFD simulation of 2-stroke engines. This paper covers the discussion of a simulation strategy for the exhaust system of a 2-cylinder 2-stroke engine until cyclic steady condition including the heat transfer over the exhaust pipe wall.
2010-09-28
Technical Paper
2010-32-0069
Gustavo Fontana, Fabio Bozza, Enzo Galloni, Daniela Siano
In this paper, an experimental and numerical analysis of combustion process and knock occurrence in a small displacement spark-ignition engine is presented. A wide experimental campaign is preliminarily carried out in order to fully characterize the engine behavior in different operating conditions. In particular, the acquisition of a large number of consecutive pressure cycle is realized to analyze the Cyclic Variability (CV) effects in terms of Indicated Mean Effective Pressure (IMEP) Coefficient of Variation (CoV). The spark advance is also changed up to incipient knocking conditions, basing on a proper definition of a knock index. The latter is estimated through the decomposition and the FFT analysis of the instantaneous pressure cycles. Contemporary, a quasi-dimensional combustion and knock model, included within a whole engine one-dimensional (1D) modeling framework, are developed. Combustion and knock models are extended to include the CV effects, too.
2010-10-25
Technical Paper
2010-01-2110
Chris De Boer, Junseok Chang, Shreeram Shetty
Spark ignition gasoline engine efficiency is limited by a number of factors; these include the pumping losses that result from throttling for load control, spark ignition and the slow burn rates that result in poor combustion phasing and a compression ratio limited by detonation of fuel. A new combustion process has been developed based on the patented concept of injection-ignition known as Transonic Combustion or TSCi™; this combustion process is based on the direct injection of fuel into the cylinder as a supercritical fluid. Supercritical fuel achieves rapid mixing with the contents of the cylinder and after a short delay period spontaneous ignition occurs at multiple locations. Multiple ignition sites and rapid combustion combine to result in high rates of heat release and high cycle efficiency. The injection-ignition process is independent from the overall air/fuel ratio contained in the cylinder and thus allows the engine to operate un-throttled.
2010-10-25
Technical Paper
2010-01-2105
Klaus Siegfried Oppenauer, Daniel Alberer, Luigi del Re
This paper presents a detailed optical and thermodynamic analysis of effects which influences the soot formation and oxidation process during Diesel combustion. To measure the actual soot concentration over crank angle an optical sensor was installed on the engine. In combination with a thermodynamic engine process calculation, based on the measured cylinder pressure, several important effects are analyzed and described in detail. The main focus of the paper is to produce knowledge on how soot dynamics is influenced by changed engine control unit (ECU) calibration parameters. A modern 4 cylinder production car Diesel engine was used for the studies, which offers a lot of opportunities to influence combustion by varying injection timing and air path ECU parameters. As a consequence discussion is done on how the analyzed effects are treated by published 0-dimensional simulation models with focus on later control and optimization application.
2010-10-25
Journal Article
2010-01-2091
Michael J. Lance, C. Scott Sluder, Samuel Lewis, John Storey
Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with nitrogen oxides (NOx) emissions standards. In order to better understand fouling mechanisms, eleven field-aged EGR coolers provided by seven different engine manufacturers were characterized using a suite of techniques. Microstructures were characterized using scanning electron microscopy (SEM) and optical microscopy following mounting the samples in epoxy and polishing. Optical microscopy was able to discern the location of hydrocarbons in the polished cross-sections. Chemical compositions were measured using thermal gravimetric analysis (TGA), differential thermal analysis (DTA), gas chromatography-mass spectrometry (GC-MS), x-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD). Mass per unit area along the length of the coolers was also measured.
2010-10-25
Journal Article
2010-01-2090
Michael Marr, James S. Wallace, Silvio Memme, Sanjeev Chandra, Larry Pershin, Javad Mostaghimi
Surface temperature and heat flux were measured in a single cylinder SI engine piston when uncoated and with two different surface coatings: a metal TBC and YSZ. Average heat flux into the piston substrate was 33 % higher with the metal TBC and unchanged with the YSZ relative to the uncoated surface. The increase with the metal TBC was attributed to its surface roughness. However, the metal TBC and YSZ reduced peak heat flux into the substrate surface by 69 % and 77 %, respectively.
2010-10-25
Technical Paper
2010-01-2119
Andreas Janssen, Martin Muether, Andreas Kolbeck, Matthias Lamping, Stefan Pischinger
Within the Cluster of Excellence “Tailor-Made Fuels from Biomass” at RWTH Aachen University, the Institute for Combustion Engines carried out an investigation program to explore the potential of future biofuel components in Diesel blends. In this paper, thermodynamic single cylinder engine results of today's and future biofuel components are presented with respect to their engine-out emissions and engine efficiency. The investigations were divided into two phases: In the first phase, investigations were performed with rapeseed oil methyl ester (B100) and an Ethanol-Gasoline blend (E85). In order to analyze the impact of different fuel blends, mixtures with 10 vol-% of B100 or E85 and 90 vol-% of standardized EN590 Diesel were investigated. Due to the low cetane number of E85, it cannot be used purely in a Diesel engine.
2010-10-25
Technical Paper
2010-01-2264
Bogdan Radu, Dinu Fuiorescu
This paper study the case of a heavy-duty spark ignition engine fueled with LPG, for which it was demonstrated that the thermal effect of the pre-knock reactions in the end-gas occur in the presence of alkenes, one of the commercial LPG main component. In this sense, the engine was operated at full load, with different spark advances generating different levels of knock, which was characterized in terms of angle and intensity. It was developed a classical two zone thermodynamic combustion model for predicting the end-gas pressure and temperature levels, which are cycle-by-cycle variables. It was made the comparison between the cycles with knock and without and it was find that in the knocking cycles case the end-gas temperature is higher, this situation being attributed to the presence of alkenes in the fuel composition.
2010-04-12
Technical Paper
2010-01-0542
Marcel Skarohlid
This paper deals with the influence of CO, CO₂, N₂, H₂, C₂H₆, C₃H₈ and C₄H₁₀ content in fuel on basic engine integral parameters. The focus is on the influence of biogas fuel composition on engine thermodynamic features. The paper describes the iterative regression method evaluating the influence of individual gas mass fraction and engine operation parameters on cumulative heat release curve of SI engines. The parameters for recalculation of heat release patterns depending on individual gas mass fraction in fuel and operation parameters are derived. The modeled cumulative heat release patterns are converted into burned fuel fraction pattern. The particular outputs are generalized using GT-POWER-based model results.
2010-04-12
Technical Paper
2010-01-0543
Chen Huang, Valeri Golovitchev, Andrei Lipatnikov
A semi-detailed chemical mechanism for combustion of gasoline-ethanol blends, which is based on sub-mechanisms of gasoline surrogate and for ethanol is developed and validated aiming at CFD engine modeling. The gasoline surrogate is composed of iso-octane, toluene, and n-heptane in volumetric proportions of 55%:35%:10%, respectively. In this way, the hydrogen-carbon atomic ratio H/C, which is around 1.87 for real gasoline, is accurately reproduced as well as a mixture equivalence ratio that is important for Gasoline Direct Injection engine applications. The integrated mechanism for gasoline-ethanol blends includes 120 species participating in 677 reactions. The mechanism is tested against experimental data on ignition delay times and laminar flame speeds, obtained for various n-heptane/iso-octane/toluene/ethanol-air mixtures under various equivalence ratios, initial temperatures, and pressures. Chemical, thermodynamic and transport properties used in the calculations are discussed.
2010-04-12
Journal Article
2010-01-0548
Itsuhei Kohri, Yuji Kobayashi, Yukio Matsushima
The technology concerning thermo and fluid dynamics is one of the important fields which have made great progress along with rapid advance in computational resources. Especially, the CFD technology has been proved as successful contribution to the development of the engine cooling system. Therefore, this technology is widely used at early phase of the vehicle development. However, a serious problem has been remained that it does not always give practical precision. Particularly, the cooling fan is one of the primary components in the cooling system to determine the performance, while practical calculation method without depending on large resources has not established.
2010-04-12
Technical Paper
2010-01-0550
Devadatta Mukutmoni, Jaehoon Han, Ales Alejbegovic, Lionel Colibert, Mathieu Helene
Accurate simulation of long term transient thermal convection is critical to automotive related thermal and fluid flow applications. For instance, long term thermal transients are relevant to “key-off” situations in which a moving vehicle brought to a stop leads to a usual initial spike in temperature followed by a drop as the heat sources are turned off. Presented are simulations of a simple tube and plate configuration that captures the contribution of all heat transfer effects and complexities of a vehicle key-off process. The simulations were performed using a coupling between the flow solver and the thermal simulation package that includes conduction and radiation effects. The simulation results were compared with the test data for steady state forced convection cases and transient natural convection cases. Good agreement was observed for both steady and transient simulations.
2010-04-12
Technical Paper
2010-01-0549
Federico Brusiani, Gian Marco Bianchi, Alberto Bianchi D' Espinosa
The fluid dynamic of fully turbulent flows is characterized by several length scales bounded between the flow field dimension (large scales) and the diffusive action of the molecular viscosity (small scale). The large scales of motion are responsible of the main momentum transport while the small scales of motion are responsible of the energy dissipation into heat. In some cases the analysis of the large scales could be enough to explain the behaviour of the fluid dynamic system under investigation but, in other cases, the effect of all the turbulent scales have to be considered. A classic example of the latter working condition is the aerodynamic field where the efficiency is dictated by a fine equilibrium between mean flow conditions (driven by large turbulent scales) and laminar/turbulent boundary layer evolution (driven by small turbulent scales).
2010-04-12
Technical Paper
2010-01-0553
Peter Gullberg, Lennart Löfdahl, Peter Nilsson, Steven Adelman
The most common fan model to use in commercial CFD software today is the Multiple Reference Frame (MRF) model. This is at least valid for automotive under hood applications. Within the industry, for this typical application, this model is commonly known to under predict performance. This under prediction has been documented by the authors' of this paper in SAE paper 2009-01-0178 and VTMS paper 2009-01-3067. Furthermore has this been documented by S.Moreau from Valeo in “Numerical and Experimental Investigation of Rotor-Stator Interaction in Automotive Engine Cooling Fan Systems”, ETC, 7th European Conference on Turbomachinery, 2007. In preceding papers a specific methodology of use has been documented and it has been shown that the MRF model under predicts performance for the airflow in a cooling system commonly with 14% in volumetric flow rate. This is for a system dominated by inertial effects.
2010-04-12
Journal Article
2010-01-0552
Paul M. Rutkowski
Seat cooling systems are becoming more common as luxury features offered by original equipment manufacturers. Despite the extensive research & application of these systems, a thermal model and comfort requirements of the occupant/seat system have not been established. Without a model or thermal criteria for comfort, the seat temperature & humidity conditions required for optimal comfort can not be defined. A synopsis of the thermal comfort conditions required to achieve an occupant's subjective comfort as well as their comfort transition points are explained. In this context a model is designed specifically from a heat and mass transfer perspective between an occupant and a seat cooling system. Focus is given to the local conduction, convection, and evaporative cooling that takes place at the body to seat surface interface.
2010-04-12
Technical Paper
2010-01-0555
Ashok Patidar
This paper broadly describes two computational fluid dynamics (CFD) analysis methods to predict the de-icing phenomenon over the vehicle windshield and front side windows. 1 Solid Modeling Method: In this method, the windshield and window glasses are modeled as solid and 2 Shell Modeling Method: Here, windshield and side window glasses are modeled as shell elements and considered as wall with defined thickness as input condition to capture the correct heat transfer effect due to the conduction and convection from warm air to ice layer. The CFD analyses by both methods are done in two key-steps: a) First, steady state velocity distributions for several different defroster flow rates are calculated; b) Secondly, based on the pre calculated velocity fields, the defogging time is estimated. The solidification and melting model is used to simulate the ice melting process over the glasses available with commercial CFD software Fluent.
2010-04-12
Technical Paper
2010-01-0554
Felix Regin
The influence of environmental changes on underhood and underbody components of a vehicle is an important issue in new vehicle design as increased engine power, cabin comfort demands and package space limitations create an increasingly difficult problem to solve. Sufficient airflow needs to be available for adequate cooling of the underhood components. The amount of air mass flow depends on the underhood geometry details: positioning and size of the grilles, fan operation, and the positioning of the other underhood components. This paper describes a prediction methodology that significantly streamlines the process of passenger car underhood thermal management by utilizing state-of-the-art computer simulation of airflow. The methodology uses a complete 3-D CAD model of all pertinent underhood components of a passenger car with a general purpose Computational Fluid Dynamics (CFD) code to simulate underhood airflow.
2010-04-12
Technical Paper
2010-01-0462
Vassilios Charisis, George Vlachos, Warren Chan, Sachi Arafat
This paper presents the design and development of a prototype Head-Up Display (HUD) interface that offer early notification warnings of potential collisions under unfavourable weather and traffic conditions. In this work we particularly focus our effort in the embedment of traffic congestion and sharp turn visual warnings in a working prototype interface. In turn we present the results of a large scale evaluation of the system on a group of forty users, which contrasted the use of the proposed HUD against a typical HDD. Finally the paper offers suggestions for further research and a tentative plan for future work.
2010-04-12
Journal Article
2010-01-0428
Michael Fuqua, Shanshan Huo, Venkata S. Chevali, Chad A. Ulven
In this study, soy-based polyurethane foam was reinforced with random oriented flax fiber to create green composite paneling. This paneling can be used as replacement for plywood in mass transit flooring. To establish optimal material properties, the flax/foam composite's density was modified through manipulation of both fiber volume fraction and foam void content in order to determine processing modification upon mechanical performance. Both static flexural testing and dynamic low velocity impact was performed. Mechanical characterization was performed by both flexural testing and screw fastener pullout studies. Resultant properties demonstrate the feasibility of lower maintenance renewable composite materials as replacement for current transit flooring.
2011-04-12
Journal Article
2011-01-0323
Brian James Abels, Kelly Kissock
Compressed air storage is an important, but often misunderstood, component of compressed air systems. This paper discusses methods to properly size compressed air storage in load-unload systems to avoid short cycling and reduce system energy use. First, key equations relating storage, pressure, and compressed air flow are derived using fundamental thermodynamic relations. Next, these relations are used to calculate the relation between volume of storage and cycle time in load-unload compressors. It is shown that cycle time is minimized when compressed air demand is 50% of compressor capacity. The effect of pressure drop between compressor system and storage on cycle time is discussed. These relations are used to develop guidelines for compressed air storage that minimize energy consumption. These methods are demonstrated in two case study examples.
2011-04-12
Technical Paper
2011-01-0271
Rami Mansour, Douglas Romilly
Rear end collisions account for approximately $9 billion annually in the United States alone. These types of collisions account for nearly 30% of all vehicle impacts making them the most common type. Soft tissue injury to the neck (i.e. “whiplash”) is typically associated with this type of collision due to the occupant dynamics of the passengers in the struck vehicle. At low relative impact velocities, whiplash-type injuries are known to occur but are typically attributed to: 1) improper seat adjustment, 2) an “out-of-position” event, or 3) a low injury threshold due to age, gender, etc. In high impact collisions, both whiplash and occupant ejection can take place, the latter placing far greater risk of injury not only to the front seat occupant, but also to any rear seat passengers as well. The automobile seating system is the predominant safety device employed to protect the occupant during these types of collisions.
2011-04-12
Technical Paper
2011-01-0272
David C. Viano, Chantal Parenteau, Roger Burnett
Objective: This study analyzed available rear impact sled tests with Starcraft-type seats that use a diagonal belt behind the seatback. The study focused on neck responses for out-of-position (OOP) and in-position seated dummies. Methods: Thirteen rear sled tests were identified with out-of-position and in-position 5 th , 50 th and 95 th Hybrid III dummies in up to 47.6 mph rear delta Vs involving Starcraft-type seats. The tests were conducted at Ford, Exponent and CSE. Seven KARCO rear sled tests were found with in-position 5 th and 50 th Hybrid III dummies in 21.1-29.5 mph rear delta Vs involving Starcraft-type seats. In all of the in-position and one of the out-of-position series, comparable tests were run with production seats. Biomechanical responses of the dummies and test videos were analyzed.
2011-04-12
Technical Paper
2011-01-0270
Leigh Berger, Lisa Fallon, Michael G. Carpenter
This study documents a method developed for dynamically measuring occupant pocketing during various low-speed rear impact, or “whiplash” sled tests. This dynamic pocketing measurement can then be related to the various test parameters used to establish the performance rating or compliance results. Consumer metric and regulatory tests discussed within this paper as potential applications of this technique include, but are not limited to, the Insurance Institute for Highway Safety (IIHS) Low Speed Rear Impact (LSRI) rating, Federal Motor Vehicle Safety Standard (FMVSS) 202a, and European New Car Assessment Program (EURO-NCAP) whiplash rating. Example metrics are also described which may be used to assist in establishing the design position of the head restraint and optimize the balance between low-speed rear impact performance and customer comfort.
2011-04-12
Journal Article
2011-01-0273
Jeffrey Braganza, Massoud S. Tavakoli, Janet Brelin-Fornari
The rear seat occupant has been the subject of an increasing number of research efforts in recent years. However, the majority of the research has focused on frontal impact, while there are also a number of studies concerned with low to moderate delta-V rear impact. Very limited work exists regarding the fate of the rear seat occupant involved in high-severity rear impact, especially when utilizing the BioRID anthropomorphic test device (ATD). Furthermore, it is evident that the out of position rear occupant, as defined by leaning forward prior to rear impact, is also of relevance to this line of research. The objective of this study is to explore and compare the response of BioRID and 50 th percentile Hybrid III in conjunction with the effects of head restraint geometry and the occupant seating configuration (normal seating versus forward leaning) in high-severity rear impact tests.
2011-04-12
Technical Paper
2011-01-0274
David C. Viano
Purpose: This study presents cases of fracture-dislocation of the thoracic spine in extension during severe rear impacts. The mechanism of injury was investigated. Methods: Four crashes were investigated where a lap-shoulder-belted, front-seat occupant experienced fracture-dislocation of the thoracic spine and paraplegia in a severe rear impact. Police, investigator and medical records were reviewed, the vehicle was inspected and the seat detrimmed. Vehicle dynamics, occupant kinematics and injury mechanisms were determined in this case study. Results: Each case involved a lap-shoulder-belted occupant in a high retention seat with ≻1,700 Nm moment or ≻5.5 kN strength for rearward loading. The crashes were offset rear impacts with 40-56 km/h delta V involving under-ride or override by the impacting vehicle and yaw of the struck vehicle. In each case, the occupant's pelvis was restrained on the seat by the open perimeter frame of the seatback and lap belt.
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