bluuebunny/crossref_metadata_2025 huggingface dataset:
Macroscopic Spray Parameters in Automotive Diesel Injector Nozzles With Different Hole Shape
Authors: Dongiovanni Claudio , Negri Claudio , Pisoni Davide
Published: February 2009

The sprays generated from three nozzles for automotive diesel engines have been compared. The nozzles were characterized by the same stationary flux and they were designed for the same engine, but with holes of different shape: cylindrical, conical and with different internal edge finishing. The nozzles have been mounted on an injection system test bench in order to characterize their hydraulic behaviour at practical test conditions for the engine on which the nozzles have to be installed. Then, the injector has been mounted on a test chamber and sprays were generated at the test conditions previously defined. Digital images of every spray plume were acquired at the same optical and injector operative conditions. An automatic digital image procedure was defined in order to evaluate the macroscopic spray characteristics: penetration and dispersion angle. This procedure was based on the Karhunen-Loeve decomposition in order to choose the appropriate threshold level for each image. The effect of the intensity threshold level on the image analysis was analysed in terms of macroscopic spray characteristics. The temporal evolutions of the sprays generated by the three nozzles were compared with one-another and the effects of practical injection timing on spray penetration were analysed. A dimensionless spray penetration correlation was developed in order to take into account the effects of the injection rate profiles on the penetration.
Service Methane Number as a Means to Avoid Knock in Natural Gas Fuelled Spark Ignition Engines
Authors: Brecq Guillaume , Rahmouni Camal , Taouri Abdellilah , Tazerout Mohand , Le Corre Olivier
Published: February 2009

Experimental investigations on the knock rating of gaseous fuels were carried out on a single cylinder SI engine of Lister-Petter make. The Service Methane Number (SMN) of different gas compositions is measured and then compared to the standard Methane Number (MN), calculated by the AVL software. Effects of engine parameters, by mean of the Methane Number Requirement (MNR) are also highlighted. A linear correlation, between the SMN and the MN, has been obtained with a maximum absolute deviation lower than 2 MN units. A prediction correlation giving the MNR from engine parameters has finally been deduced from experimental data with a good accuracy (mean absolute deviation of 0.5 MNR unit).
Methodology in the Development Process of Large Gaseous Fuelled Engines
Authors: Kogler Gerhard , Wimmer Andreas , Eichlseder Helmut , Schnessl Eduard , Winter Hubert
Published: February 2009

High demands are placed on large gaseous-fuelled engines regarding performance, fuel consumption and emissions. Because of the different applications of gaseous-fuelled engines (block-type thermal power stations, generation of electric power in a stand alone plant, etc.) and the use of different kinds of gases (natural gas, wood gas, pyrolysis gas, dump gas, etc.), the optimization process can be seen as a very complex task. Today engines have already reached a high level of development and further improvements can only be realized with very high expenditures. Experience has shown that a purely experimental approach is no longer sufficient and therefore the application of modern simulation tools is necessary. In this paper a combined development process is described consisting of simulation, experimental investigations on a single cylinder research engine and transfer on a full scale engine as an example for the optimization of a gas-purched prechamber concept.
Unified Approach to Generate Crankshaft Dynamic Models for 3D and Torsional Vibration Analyses
Authors: Parikyan Tigran
Published: February 2009

The paper considers two kinds of crankshaft dynamic models which can be used to analyze cranktrain dynamics: structured model, consisting of mass nodes connected by binary elastic elements — for 3D dynamic simulation, and equivalent torsional model — for torsional vibration analysis. A methodology of automatic generation of both models, sharing the same data in form of CAD model, is presented. The dynamic equivalence of both models is demonstrated, and their correlation with the original volumetric FE model is discussed. The main advantage of the method is a significant reduction of effort to generate the structured and torsional models.
3-Way Catalyst Testing at VTT Energy
Authors: Sartain John , Newburry Don , Pitkanen Mikko , Ikonen Markku
Published: February 2009

Emissions regulations on stationary, natural gas fired reciprocating engines are becoming increasingly tighter throughout the United States. In addition to lower NOx, CO and hydrocarbon limits, regulation of HAP (Hazardous Air Pollutant) emissions has become more prevalent. Rich burn (stoichiometric) natural gas engines are widely used in the oil and gas industry, as well as in distributed power generation. Due to the low oxygen content in the exhaust, these engines are suitable for 3-Way catalyst, which simultaneously reduces NOx and oxidizes CO and hydrocarbons. A series of 3-Way catalyst tests were conducted on a small natural gas engine at the VTT Technical Research Centre in Espoo, Finland. The overall goals of the testing were to determine the ability of various 3-Way catalysts to meet California emissions regulations and to gather data on HAPs emission reductions. The testing was carried out in two phases. In phase 1, several fresh catalysts were tested at the NOx/CO crossover point (i.e., the point where CO and NOx reduction percent is approximately equal) by using an air/fuel ratio controller to keep the exhaust oxygen level constant. Detailed emissions measurements of both regulated and unregulated emissions were taken. The measurements included NOx, CO, hydrocarbon species, CH2O, N2O, NH3, and H2. In phase 2, the effects of exhaust lambda variation on NOx and CO were studied in more detail, with aged catalyst. Also, different engine loads were tested to vary the space velocity and temperature. This paper describes the testing in more detail and presents some of the resulting data.
The Use of a Three-Zone Combustion Model to Determine Nitric Oxide Emissions From a Homogeneous-Charge, Spark-Ignited Engine
Authors: Caton Jerald A.
Published: February 2009

Nitric oxide emissions were estimated for a homogeneous-charge, spark-ignited automotive engine using a cycle simulation which employed three zones for the combustion process: (1) unburned gas, (2) adiabatic core region, and (3) boundary-layer gas. The use of the adiabatic core region has been shown to be especially necessary to capture the production of nitric oxides which are highly temperature dependent. The effects of major engine parameters such as equivalence ratio, spark timing, inlet manifold pressure, and engine speed on nitric oxide emissions are examined. In particular, the detail reasons for the effects of these engine parameters on the nitric oxide emissions are presented. Comparisons are completed between the computed values and a set of published measurements for the nitric oxide concentrations. Although not all engine parameters were known, reasonable agreement is demonstrated for most cases. In particular, the variations of nitric oxide concentrations as engine speed increased were duplicated. As an example, four operating conditions are examined in detail to help explain the measured results. Nitric oxide emissions are shown to be mainly the net result of gas temperatures, oxygen concentrations, and residence times.
Cost Effective Engine Strategies for Future Off-Highway Emissions Limits
Authors: Freeman H. D. , Sharman G. G. , Such C. H. , Nicol A. J. , Weller G. B.
Published: February 2009

This paper reviews the options available to the engine manufacturer to comply with US off-highway Tier 3 emissions limits and beyond. The most cost-effective solutions are considered and discussed. Possible technical scenarios for the longer-term development of off-highway engines are reviewed.   NOTE: This paper was presented at the ASME 2003 Internal Combustion Engine Division Spring Technical Conference but was printed in the ASME 2003 Internal Combustion Engine and Rail Transportation Divisions Fall Technical Conference proceedings, pages 419–426. It should appear under the Application and Operation heading.
Advanced Bearing Design for Gas- and Alternative Fuel Engines
Authors: Ga¨rtner Walter , Aufsicher Rainer , Humer Johannes , Rumpf Thomas
Published: February 2009

Gas engine development moves progressively forward not only in direction of fuel efficiency and power density but also in using alternative gases and fuels. For bearings and bushings this means that they will experience more severe operating conditions with respect to load, cavitation, corrosion and wear. According to the demand for increased performance, bearings with hard surfaces — with sputtered overlays — have been installed and have now served for several thousand hours of operation. These bearing types offer not only high load carrying capability and wear resistance but in addition show increased corrosion and cavitation stability which results in an extraordinary life expectancy.
Exhaust Emissions of an Off-Road Diesel Engine Driven With a Blend of Diesel Fuel and Mustard Seed Oil
Authors: Niemi Seppo A. , Tyrva¨inen Juha M. , Laure´n Mika J. , Laiho Va¨ino¨ O. K.
Published: February 2009

In the near future, crude oil based fuels must little by little be replaced by biofuels both in the region of the European Union (EU) and in the United States. Bearing this in mind, a Finnish-made off-road diesel engine was tested with a biofuel-diesel fuel blend in the Internal Combustion Engine (ICE) Laboratory of Turku Polytechnic, Finland. The biofuel was cold-pressed mustard seed oil (MSO). The engine operation, performance and exhaust emissions were investigated using a blend of 30 mass-% MSO and 70 mass-% diesel fuel oil (DFO). The injection timing of the engine was retarded considerably in order to reduce NOx emissions drastically. The main target was then to find out, whether the blended oxygen containing MSO would speed up the combustion so that the particulate matter (PM) emissions would remain unchanged or even decrease despite the injection retardation. As secondary tasks of the study, the NOx readings of the CLD and FTIR analyzers were compared, and exhaust contents of unregulated compounds were determined. Retarding the injection timing resulted in a significant decrease of NOx emissions, but in an increase in smoke, as expected. At retarded timing, the NOx emissions remained almost unchanged, but the amount of smoke decreased when the engine was run with the fuel blend instead of DFO. At retarded timing at rated speed, the number of ultra-fine particles decreased, but the amount of large particles increased with DFO at full load. At 10% load, however, the particle number increased in the entire particle size range due to retardation. At both loads, the use of the fuel blend slightly reduced larger particles, whereas the number of small particles somewhat increased. At full load at an intermediate speed of 1500 rpm, the PM results were very similar to those obtained at rated speed. At 10% load with DFO, however, the injection retardation led to a higher number of larger particles, the smaller particles being at almost an unchanged level. With the fuel blend, the particle number was now higher within almost the whole particle diameter range than with DFO. Considerably higher NO2 contents were usually detected with FTIR than with CLD. The shape of the NOx result curves were rather similar independent of which one of the analyzers was used for measurements. The NOx contents were, however, generally some ten ppms higher with FTIR. The exhaust contents of unregulated compounds were usually low.
Laser Ignition of Methane-Air Mixtures at High Pressures and Diagnostics
Authors: Kopecek Herbert , Charareh Soren , Lackner Max , Forsich Christian , Winter Franz , Klausner Johann , Herdin Gu¨nther , Wintner Ernst
Published: February 2009

Methane-air mixtures at high fill pressures up to 30 bar and high temperatures up to 200 °C were ignited in a high pressure chamber with automated fill control by a 5 ns pulsed Nd:YAG laser at 1064 nm wavelength. Both, the minimum input laser pulse energy for ignition and the transmitted fraction of energy through the generated plasma were measured as a function of the air/fuel-equivalence ratio (λ). The lean side ignition limit of methane-air mixtures was found to be λ = 2.4. However, only λ < 2.2 seems to be practically usable. As a comparison, the limit for conventional spark plug ignition of commercial natural gas engines is λ = 1.8. Only with excessive efforts λ = 2.0 can be spark-ignited. The transmitted pulse shape through the laser-generated plasma was determined temporally as well as its dependence on input laser energy and properties of the specific gases interacting. For a first demonstration of the practical applicability of laser ignition, one cylinder of a 1 MW natural gas engine was ignited by a similar 5 ns pulsed Nd:YAG laser at 1064 nm. The engine worked successfully at λ = 1.8 for a first test period of 100 hours without any interruption due to window fouling and other disturbances. Lowest values for NOx emission were achieved at λ = 2.05 (NOx = 0.22 g/KWh). Three parameters obtained from accompanying spectroscopic measurements, namely water absorbance, flame emission and the gas inhomogeneity index have proven to be a powerful tool to judge laser-induced ignition of methane-air mixtures. The following effects were determined by the absorption spectroscopic technique: formation of water in the vicinity of the laser spark (semi-quantitative); characterization of ignition (ignition delay, incomplete ignition, failed ignition); homogeneity of the gas phase in the vicinity of the ignition and the progress of combustion.
Application of Process Calculation of the Internal Combustion Engine for the Analysis of Torsional Vibrations in Marine Drives
Authors: Gold P. W. , Philipp Torsten , Schelenz Ralf , Buehren Michael
Published: February 2009

Regarding driving units with combustion engines, it is primarily the torsional vibrations caused by the unsymetrical gas forces, inertial forces and out-of-balance forces which may cause harm to the driveline. The program DRESP was developed at the Institute of Machine Elements and Machine Design (IME) of the RWTH Aachen in order to simulate such nonlinear torsional vibration systems. The program has been established as an efficient simulation tool in numerous companies for driveline analysis. Fourier series of gas pressure moments are used for the simulation of torsional vibrations in order to simulate the periodic excitation of combustion engines. But this is only applicable at a certain stationary operation point of the engine. To avoid this disadvantage, a simulation model based on a combustion process calculation can be used instead. It computes the gas and mass excitation forces by modeling the combustion process and the kinematic of the crank drive for every cylinder. The theoretical basis is the so called One Zone Model according to Vibe which is a simplified thermodynamic model of the cylinder. The presentation shows a DRESP-simulation using the example of a modern marine drive with a two-stroke diesel engine. It shows the dynamic behavior of the power-train during an engine-startup process from zero to nominal speed.
Methods for Specific Emission Evaluation in SI Engines Based on Calculation Procedures of Air-Fuel Ratio: Development, Assessment and Critical Comparison
Authors: d’Ambrosio Stefano , Spessa Ezio , Vassallo Alberto
Published: February 2009

New computational procedures are proposed for evaluating the exhaust brake specific mass emissions of each pollutant species in IC engines. The procedures start from the chemical reaction of fuel with combustion air and, basing on the measured exhaust raw emissions THC, CH4, NOx, CO, O2, CO2, calculate the volume fractions of the compounds in the exhaust gases, including those that are not usually measured, such as water, nitrogen and hydrogen. The method also takes the effects of various fuel and combustion air compositions into account, with particular reference to different natural gas blends as well as to the presence of water vapor, CO2, Ar and He in the combustion air. The molecular mass of the exhaust gases is then evaluated and the brake specific emissions can be obtained if the exhaust flow rate and the engine power output are measured. The methods stem from the extension of the different procedures that are used in the literature to evaluate α from measured raw volume emissions of IC engines running on conventional fuels. In the present study, a new algorithm is developed so as to generalize and refine all the mentioned α evaluation procedures, keeping conventional and alternative fuel compositions into account. First, the algorithm is applied to the evaluation of α in an automotive bi-fuel SI engine running on gasoline and CNG under a wide range of operating conditions. The α evaluation tests were carried out with a carefully controlled multipoint sequential injection system for both gasoline and CNG fueling. The results are compared to those obtained from the directly measured air and fuel mass flow rates as well as from more conventional UEGO sensor data. The algorithm is then applied to the evaluation of the brake specific mass emission of each pollutant species under gasoline and CNG engine operations for different steady-state working conditions. The sensitivity of results to the main engine working parameters, the influence of environmental conditions (in particular the effect of air humidity on NOx formation) and the experimental uncertainties are determined. The specific emissions calculated from the proposed algorithm are finally compared to those obtained by applying SAE and ISO recommended practices.
Advanced Screw Pumps for Heavy Fuel Oil Conditioning Systems
Authors: Schneider Christoph K. , Naucke Hans-J. , Wolf Ju¨rgen M.
Published: February 2009

Failures of screw pumps in marine fuel oil conditioning systems are some of the most frequent incidents affecting a ship’s availability. In order to identify the possible reasons a systematic investigation was initiated. The result makes obvious that most of the defects are related to shaft seal failures. The respective scenarios of seal defects are discussed in detail as well as possible counter measures. However, the results finally have revealed that pump designs with mechanical shaft seals will always incur a distinct risk of breakdown. A decisive step forward in solving this problem is to completely avoid the shaft seal. The alternative technology of hermetically sealed pumps with magnetic coupling will be presented in its current state of the art.
Numerical Simulation of Heat and Fluid Flow Behavior in a Pipe Flow With Sinusoidal Boundary Condition
Authors: Shojaee Fard M. H. , Noorpoor A. R.
Published: February 2009

In this investigation a two-dimensional airflow and heat transfer with sinusoidal boundary condition analysis was conducted. Both laminar and turbulent sinusoidal pipe flows were investigated numerically for Remax = 2000, 10000, 20000 and 60000. The results are compared with experimental results of previous investigators [2], [5]. Comparing non-dimensional velocity amplitudes also checks predictions of the flow regime on present sinusoidal flow conditions. A high Reynolds number RNG k-ε turbulence model was used for turbulent flows. An available code, which is basis on finite volume and can solve Nervier-stokes equations on the structured grids, is used. After discrete equations on the control volume, physical properties flux on the control volume by means of first-order upwind difference scheme is calculated. Then, to solve algebraic equations the SIMPLE method is used. Computational results are presented and discussed for velocity, pressure drop, wall shear, temperature, heat flux, and convection coefficient.
A Generic Simulation Model for Cylinder Kit Vibro-Acoustics: Part I — Piston Slap in Mixed Lubrication Regime
Authors: Herbst Hubert M. , Offner Gu¨nter , Priebsch Hans H.
Published: February 2009

Precise models for the numerical simulation of contacting engine parts cause conflicting demands in efficiency and accuracy. This is particularly valid for the cylinder kit of combustion engines. Here impacts of piston and liner surfaces via the oil film effect friction, wear and vibro-acoustic excitation. As the first of parts, this contribution describes a mixed lubrication model for the cylinder kit considering effects of mass, elasticity, surface roughness and hydrodynamics. The model is used to predict the impact between piston and liner and the resulting vibration excitation near FTDC of a running four cylinder diesel engine. The calculated results are validated by means of measurements. The significant effects of specific model parameters are discussed, e.g. oil filling between running shapes of the contacting structures.
Adaptive Control of the Idle Speed
Authors: Wendeker Miroslaw , Czarnigowski Jacek
Published: February 2009

Idle speed control of an spark ignition automotive engine based on adaptive techniques has been presented. In the paper the ignition advance control was activated to stabilise the idle speed. The adaptation of the spark advance angle requires defining an adaptive coefficient, which is a compromise between operation speed and estimation accuracy. The adaptive coefficient design was evaluated through engine testing, and the performance was compared with an up-to-date tuned PID controller. The success of the adaptive controller was demonstrated in engine testing. The controller tracks not only the set point speed but also shows robustness to the load torque disturbances.
Characterization of the Viscosity of Blends of Dimethyl Ether With Various Fuels and Additives
Authors: Bhide Shirish , Morris David , Leroux Jonathan , Wain Kimberly S. , Perez Joseph M. , Boehman Andre´ L.
Published: February 2009

Dimethyl ether (DME) is a potential ultra clean diesel fuel. Dimethyl ether burns without producing the smoke associated with diesel combustion and can be manufactured from synthesis gas or methanol. However, DME has a low viscosity compared to diesel fuel and has insufficient lubricity to prevent exc essive wear in fuel injection systems. One strategy to utilize DME is to blend it with diesel fuel to obtain cleaner burning fuels that retain satisfactory fuel properties. In the present work, the viscosity of blends of DME and various fuels and additives was characterized, including a federal low sulfur fuel, soybean oil, biodiesel and various lubricity additives, over a range of blend ratios. A methodology was developed to utilize a high pressure capillary viscometer to measure the viscosity of pure DME and blends of DME and other compounds in varying proportions and at pressures up to 3500 psig. While DME is miscible in diesel fuel at any mixture fraction when the blend is held under pressures of 75 psi or above, the viscosity of the blends is below the ASTM diesel fuel specification for even a 25 wt.% blend of DME in diesel fuel. None of the additives or fuels provides adequate viscosity when blended with DME unless the blend contains less than 50% DME. Viscosity, rather than lubricity, may be the limiting factor in utilizing DME.
A Modified Combustion Model to Simulate CNG Heavy Duty Fuelled by Using KIVA 3 Code
Authors: Andreassi Luca , Cordiner Stefano , Mulone Vincenzo , Rocco Vittorio
Published: February 2009

The use of CNG as a fuel for SI engines represents a feasible solution to improve engine fuel economy (so reducing also CO2 emissions) and to face with short term urban pollution. To full exploit its potential is, however, necessary to tailor engine characteristics to this gaseous fuel in order to optimize its performances. Numerical simulation of these engines plays an important role in the design procedure, but specific problems related to CNG combustion have to be solved. In the present paper this task is performed by means of a modified version of KIVA-3 with respect to the combustion model formulation. The modified combustion model formulation is based on flamelet hypothesis, and constitutes an extension of the classical BML concept. Its formulation avoids any explicit dependence on turbulent time (different from the traditional approach based on “characteristic times”), by modeling length scales on the basis of laminar flames properties. The numerical results have been compared with the experimental ones carried out at the CNR Istituto Motori of Naples under different engine loads, engine speeds and air/fuel mixture conditions. The results obtained are really encouraging, even under lean conditions when the interaction between turbulent flow field and the involved combustion phenomena becomes more complex.
Flow Simulation in Port and Cylinder of a Small Motorcycle Engine With Inclined Valve
Authors: Luo Ma-Ji , Huang Zhen , Chen Guo-Hua , Ma Yuan-Hao
Published: February 2009

The in-cylinder flow of an internal combustion engine has great effect on the major engine performance characteristics. To understand the complex intake phenomena in a small high-speed two-valve-per-cylinder motorcycle engine, a numerical analytic model based on the KIVA-3 code is developed for the three-dimensional transient intake flow, including a moving piston and a moving inclined intake valve. The valve model adopts the body-fitted technique and the dynamic grids induced by the moving valve are automatically generated by the grid remeshing method. Turbulence is represented by k-ε model. Comparison with the measured engine cylinder pressure shows that the simulation result is generally in good agreement with the experiment. The calculated results reveal the formation of the in-cylinder tumble motion, the variation of tumble ratios, turbulence kinetic energy and the cylinder pressure. The effects of engine speeds on the intake process are also investigated. The simulation results provide important information for the design of engine intake system.
Dynamic Response of Automotive Catalytic Converters to Modulations in Engine Exhaust Compositions
Authors: Shamim Tariq
Published: February 2009

This paper presents a computational investigation of the effect of composition modulations on an automotive catalytic converter. The objective is to develop a better fundamental understanding of the converter’s performance under actual driving conditions. Such an understanding will be beneficial in devising improved emission control methodologies by exploiting the catalyst transient behavior. The study employs a single-channel based, one-dimensional, non-adiabatic model. Two types of imposed transients (sinusoidal and step changes) are considered. The results show that composition modulations cause a significant departure in the catalyst behavior from its steady behavior, and modulations have both favorable and harmful effects on pollutant conversion. The departure is relatively significant for catalyst CO and HC conversion performance. The operating conditions and the modulating gas composition have substantial influence on catalyst behavior. Near stoichiometric condition, modulations of HC concentration have relatively greater effect and result in increased CO and HC conversions. Modulations of CO, on the other hand, result in a decrease of CO conversion. The effect of CO modulations on HC conversion is slightly positive. For the conditions studied, NO modulations generally do not result in any significant change in catalyst performance.
Eddy Current Brake Control for Test Cycles Simulation
Authors: Corti Enrico
Published: February 2009

On-vehicle (rolls dynamometer or road) tests are usually more expensive and time-consuming than test bench ones. Furthermore, sometimes results would be useful during vehicles design phase. The paper aim is to present a methodology that allows simulating the vehicle on an engine test cell, by properly controlling the bench actuators. Engine operating conditions mainly depend on speed and load, which are determined by the vehicle driving conditions: the speed-time trend assigned for the vehicle must be converted into equivalent speed-time and load-time trends for the engine, and used for feedback control of brake and accelerator actuators. To evaluate the engine load torque it is necessary to know vehicle characteristics (mass, gear ratios, wheels radius, drag coefficient, frontal area, etc.) and driving conditions: the real vehicle can thus be substituted with a virtual vehicle. The methodology has been applied to simulate an ECE-EUDC driving cycle, which is usually carried out on the rolls dynamometer, as imposed by regulations. During such test the vehicle has to follow an assigned speed-time trajectory, while road load and vehicle inertia are simulated and calibrated using a standard procedure. The test is subject to human error, since the driver does not follow exactly the theoretical speed trend, while using robot-drivers increases the setup cost. The same test has been reproduced on a standard engine bench. This setup would be useful to tune the engine correctly and to study the effects of vehicle characteristics variation, thus allowing to determine the correct strategy for emissions reduction, or to estimate the vehicle emission performance, before it is available for chassis dynamometer tests. The same system could be used for real time implementation of control strategies involving both the vehicle and the engine, such as traction control algorithms. Furthermore driving conditions simulations, executed by electronically controlling engine speed and load trajectories, would be more repeatable than human driving on the chassis dynamometer, and their cost would be substantially smaller. The paper shows how the vehicle speed trend can be converted into engine speed and load trends with a physical system model, and then used to control the bench using a real time control system, thus performing a vehicle driving cycle simulation.
Multiple Misfire: Detection and Cylinder Isolation Based on Engine Speed Measurement
Authors: Cavina Nicolo`
Published: February 2009

The diagnosis of misfire events (or missing combustions) is enforced by On-Board Diagnostics regulations (such as CARB OBD II or European OBD) over the whole engine operating range, for all vehicles equipped with spark ignition engines. Such regulations define both the minimum misfire frequency that is to be detected (related to catalyst damage and/or increased hydrocarbons emissions), and the various misfire patterns that the diagnostic algorithm should be able to detect. In particular, single (no more than one missing combustion per engine cycle) and multiple (more than one misfiring cylinder within the same engine cycle) misfire patterns are to be diagnosed, and the cylinder in which the misfire took place is to be isolated only when single misfires take place (cylinder identification is still not mandatory for multiple misfires). Various single misfire detection methodologies have been successfully developed in recent years (mostly based on the engine speed signal), and this type of misfire diagnosis is still challenging for engines with a high number of cylinders, especially during operating conditions characterized by high engine speed and low load. On the other hand, the detection of multiple misfires is still difficult even for the typical four cylinder engine, since their effects on the engine speed trend have not yet been clarified. In fact, a misfire occurrence is characterized by a sudden engine speed decrease and a subsequent damped torsional vibration. In case of multiple misfires, the engine speed oscillation induced by the first misfiring cylinder may still be present when the second missing combustion takes place, and the resulting engine speed waveform may be erroneously interpreted by the diagnostic algorithm, thus resulting in the improper cylinder being identified or missed detection of a misfiring cylinder. This paper deals with the identification of a specific pattern in the instantaneous engine speed trend, induced by a missing combustion and characteristic of the system under study, that allows performing the desired multiple misfire detection. The methodology has been designed in order to be run on-board, thus requiring low computational power and memory allocation. Its implementation has shown that false alarms can be avoided and correct cylinder isolation is possible, also in presence of multiple misfires. Experimental tests have been performed on a 1.2 liter spark ignition engine mounted in a test cell. Various multiple misfire patterns have been induced by controlling ignition and injection of the various cylinders. In-cylinder pressure signals have been acquired together with the instantaneous engine speed, in order to verify the capability of the methodology.
Benefits With Common Rail Injection for Medium Speed Engines
Authors: Schlemmer-Kelling Udo , Montag Thomas
Published: February 2009

The NOx emission of sea going ships is limited by the IMO. The black smoke emission is in the focus of the port authorities and the ship owners. More stringent limits are expected for the near future. Caterpillar Motoren decided to be pro active and to start an emission reduction program in the mid of the nineties. Inside the engine technology like: higher compression ratio, Miller Cycle, injection tuning and internal exhaust gas recirculation were investigated to reduce the NOx Emission. To lower the soot emission a Common Rail system was implemented. The effects of Pre-, Post- and Split injections were optimized for further emission reductions. A special trim of the injection characteristic can improve the transient load acceptance of the engine. A low emission strategy was defined.   NOTE: This paper was presented at the ASME 2003 Internal Combustion Engine Division Spring Technical Conference but was printed in the ASME 2003 Internal Combustion Engine and Rail Transportation Divisions Fall Technical Conference proceedings, pages 443–454. It should appear under the CIMAC heading.
Improving the Performance of Gas Engine Oils: A New Generation of Geo-Specific Additive Systems
Authors: Chambard Laurent , Smythe John
Published: February 2009

Additive technologies able to successfully lubricate gas engines have been available for many years, but in recent years the acceleration of both commercial and technical demands placed on gas engine lubricants has highlighted the performance limits of traditional additive solutions. One of these limits is the ability to reach long and very long oil drains, required by an increasing number of operators. Since traditional additive chemistries on conventional base oil systems have reached their limits in that respect, focus has been increasingly placed on using higher performance base oils so that longer oil drains can be reached. However, traditional additive chemistries have often proved to struggle in these higher performance base oils, particularly in the aspect of deposit control — demonstrating that a new generation of additive systems for the formulation of gas engine oils is needed. The authors present one such generation of additive systems, developed around off-the-beaten-track detergent technology; providing superior control of oxidation and deposits. Such additive systems can be used either in conventional base oil systems with improved drain interval, or in high performance base oil systems with very long drain interval and excellent control of deposits. Besides the description of the chemistry involved, the authors also present a methodology of performance evaluation in the laboratory, and compare this methodology with the performance perceived in the field.
NOx Emissions From Oceangoing Ships: Calculation and Evaluation
Authors: Koehler Horst W.
Published: February 2009

Currently available global inventories of nitrogen oxides (NOx) and other pollutant emissions from merchant ships are based, at least partly, on data published by international marine bunker fuel suppliers. However, the uncertainty of such data seems to be quite high, because the figures released by bunker fuel companies might be incomplete or based, for example, on data collected from only the largest ports. Besides, all similar other studies conducted so far were based on simplified average emission and fuel consumption characteristics of diesel engines and did not take into account variations with engine type, size, engine load and engine speed, as well as only being valid for new state-of-the-art diesel engines as supplied by the industry today. Furthermore, fuel consumption rates of the auxiliary engine equipment onboard vessels were neglected. The author therefore adopted a different approach by calculating the actual bunker amount and the fleet’s 2001 NOx emissions in order to reduce uncertainty in existing inventories and to assist in achieving a better modeling of the effects of ships’ pollutants on atmospheric chemistry. For this study, all ships of 100 gross tonnage (gt) and above were taken into account. This methodology resulted in a significantly higher world fleet fuel consumption, and, consequently, much higher oceangoing ships’ NOx emissions than known or anticipated so far. In spite of the fleet’s high NOx emission rate in absolute figures this paper shows, that when emissions are based on the annual seaborne trade, merchant shipping is an environmentally efficient mode of transportation of freight.
Experimental Modal Analysis of a 750 kW Wind Turbine for Structural Model Validation
Authors: Molenaar David-P.
Published: February 2009

In this paper the systematic structural modeling approach implemented in DAWIDUM is validated by experimental modal test data. The data were collected from an instrumented Lagerwey LW-50/750 wind turbine. Pre-test analysis was performed on two DAWIDUM models describing the structural dynamics of the Lagerwey LW-50/750, in order to be able to determine the frequency range of interest, the required input force magnitude, the driving point on the tower, and the accelerometer locations. The mechanical structure of the turbine is excited by applying a static load to the tower top of the wind turbine, and suddenly releasing this load via a quick release mechanism. The turbine was parked during all testing. The structure was instrumented with one force transducer in-line with the cable to measure the applied load, and 19 accelerometers on both the tower and the three rotor blades to measure the resulting response. The first results show that it is possible to derive accurate dynamic wind turbine models from design data using the presented modeling approach.
Investigation of the IEC Safety Standard for Small Wind Turbine Design Through Modeling and Testing
Authors: Jonkman Jason , van Dam Jeroen , Forsyth Trudy , Davis Dean
Published: February 2009

Since 1999, the International Electrotechnical Commission (IEC) Maintenance Team 2 (MT2) has been working on a revision of the IEC 61400–2 standard on the safety, quality, integrity, and design requirements of small wind turbines (SWTs). During this effort, a study was conducted to evaluate the quality of the structural design criteria specified by the original –2 standard. Test measurements and aeroelastic predictions of loads were gathered for a collection of SWTs and evaluated against the simplified load models and load cases specified in the standard. The collection of turbines included variations in rotor size, blade number, rotor location (upwind / downwind), hub type (rigid / teetered), yaw mechanism (free / active), and others. In general, the comparison of load measurements and model predictions exemplified the inaccuracy of the design load levels in the original –2 standard and suggested methods of improvement. Revisions being made to the standard include enhanced load models, new load cases, and improved safety factors. This work should culminate in a revised IEC 61400–2 standard that has a higher degree of applicability and dependability than the original.
Numerical Investigations of Nacelle Anemometry for Horizontal Axis Wind Turbines
Authors: Smai¨li Arezki , Masson Christian
Published: February 2009

This paper presents a numerical method for investigating nacelle anemometry of an horizontal axis wind turbine. The flowfield around the turbine and nacelle is described by the Reynolds averaged Navier-Stokes equations. The k–ε model has been chosen for the closure of time-averaged turbulent flow equations. The turbine is modeled using the actuator disk concept. Most of the nacelle region is represented by it real geometrical shape as wall boundary, except for the cooling system (radiator) of the electric generator which is modeled as a permeable surface with some prescribed pressure jump. The main purpose of this paper is to establish the relationship between the nacelle wind speed and free stream wind speed for an isolated turbine, in order to assess the impacts of the variation of some operational parameters (e.g. blade pitch angle changes), as well as atmospheric turbulence, on this relationship. The simulation results have been compared with the experimental data (from a typical stall-controlled wind turbine rated more than 600kW and comercially available). In general, good qualitative agreements have been found proving the validity of the proposed method. However, the level of accuracy is still insufficient for use in power performance testing. On the other hand, the numerical method might be a useful tool for locating nacelle anemometers.
A Parallel h-Adaptive Finite Element Model for Wind Energy Assessment in Nevada
Authors: Pepper Darrell W. , Chen Yitung , Lombardo Joseph M.
Published: February 2009

A Petrov-Galerkin finite element model that employs local mesh adaptation is being developed to determine potential wind energy sites within the state of Nevada. Meteorological data collected from various private, county, city, and government agencies are used to generate diagnostic flow fields, which subsequently provide initial conditions for the prognostic solution of the time-dependent equations of motion and species transport. The model runs on a multiprocessor SGI Onyx 3800. Results of the data collection, including wind energy site forecasts, will be made available on the web when the assessment for the entire state is completed.
Naval and Non-Naval WARP™ Offshore Wind Power Systems With Integral Fuel Cells
Authors: Weisbrich Alfred L. , Smith William , Weisbrich Gu¨nther J.
Published: February 2009

Environmentally clean and green energy is becoming increasingly a requirement of electric power delivery systems. The focus on energy security and terrorism makes an indigenous, sustainable and distributed energy resource increasingly attractive. Distributed wind power has been shown to be a good and economic means for generating clean power in good wind sites, even on an intermittent basis. However, the best wind sites are located offshore where deeper water makes current large bladed windmills uneconomic. A low cost and patently unique modular wind power technology, designated a Wind Amplified Rotor Platform (WARP™) system technology, has been investigated which projects attractive technical and economic benefits when tension leg deployed in deeper water sites where big rotor windmills are impractical. Under marine offshore use these designated e-Sea WARP™ units may include integral gas turbines or fuel cells. The latter may cogenerate with WARP windpower generated hydrogen fuel stored in onboard buoyancy tanks to supply ondemand electric energy which may be shown to be under $.02/kWhr to under $.04/kWhr. Electrical loads from electric utilities, military facilities or on-board naval operations may be serviced. Large environmental, economic, and strategic benefits may be realized by use of this technology for commercial and/or naval/coast guard sentry operations. In essence, e-Sea WARP™ systems may provide sustainable ultra-clean on-demand electricity to onboard naval systems or to nearby energy demand centers on shore by submarine cable from normally excellent wind sites miles from shore at sea.
Roughness Sensitivity Considerations for Thick Rotor Blade Airfoils
Authors: van Rooij R. P. J. O. M. , Timmer W. A.
Published: February 2009

In modern wind turbine blades airfoils of more than 25% thickness can be found at mid-span and inboard locations. In particular at mid-span aerodynamic requirements dominate, demanding a high lift-to-drag ratio, moderate to high lift and low roughness sensitivity. Towards the root srtuctural requirements become more important. In this paper the performance for the airfoil series DU, FFA, S8xx, AH, Riso̸ and NACA are reviewed. For the 25% and 30% thick airfoils the best performing airfoils can be recognized by a restricted upper surface thickness and a S-shaped lower surface for aft-loading. Differences in performance of the DU 91-W2-250 (25%), S814 (24%) and Riso̸-A1-24 (24%) airfoil are small. For a 30% thickness the DU 97-W-300 meets the requirements best. At inboard locations the influence of rotation can be significant and 2d wind tunnel tests do not represent the characteristics well. The RFOIL code is believed to be capable of approximating the rotational effect. In particular the change in lift characteristics in the case of leading edge roughness for the 35% and 40% thick DU airfoils, respectively DU 00-W-350 and DU 00-W–401, is remarkable. Due to the strong reduction of roughness sensitivity the design for inboard airfoils could primarily focus on high lift and structural demands.
Yaw Aerodynamics Analyzed With Three Codes in Comparison With Experiment
Authors: Madsen Helge Aagaard , So̸rensen Niels N. , Schreck Scott
Published: February 2009

Yaw aerodynamics were computed with three codes of different complexity; 1) The 3D Navier Stokes solver Ellipsys3D using 5–8 million grid points; 2) HAWC3D which is a 3D actuator disc model coupled to a blade element model and using 20–30.000 grid points and 3) HAWC, a finite element based aeroelastic code using The Blade Element Momentum (BEM) model for the aerodynamics. Simulations were performed for two experiments. The first is the field rotor measurements on a 100 kW turbine at Risoe where local flow angle (LFA) and local relative velocity (LRV) at one radial station have been measured in a yaw angle interval of ±60°. The other experiment is the NREL measurements on a 10 m rotor in the NASA Ames 80 ft × 120 ft wind tunnel. LFA were measured at five radial stations and data for the 45° yaw case were analyzed. The measured changes in LFA caused by the yawing were used as the main parameter in the comparison with the models. In general a good correlation was found comparing the Ellipsys3D results with the LFA measured on the NREL rotor whereas a systematic underestimation of the amplitude in LFA as function of azimuth was observed for the two other models. This could possibly be ascribed to upwash influence on the measured LFA.
Structures and Interactions Underlying Rotational Augmentation of Blade Aerodynamic Response
Authors: Schreck S. , Robinson M.
Published: February 2009

Blade rotation routinely and significantly augments aerodynamic forces during zero yaw HAWT operation. To better understand the flow physics underlying this phenomenon, time dependent blade surface pressure data were acquired from the NREL Unsteady Aerodynamics Experiment, a full-scale HAWT tested in the NASA Ames 80 ft × 120 Ft wind tunnel. Time records of surface pressures and normal force were processed to obtain means and standard deviations. Surface pressure means and standard deviations were analyzed to identify boundary layer separation and reattachment locations. Separation and reattachment kinematics were then correlated with normal force behavior. Results showed that rotational augmentation was linked to specific separation and reattachment behaviors, and to associated three-dimensionality in surface pressure distributions.