bluuebunny/crossref_metadata_2025 huggingface dataset:
Detailed Heat Transfer Measurements in a Model of an Integrally Cast Cooling Passage
Authors: Ieronymidis Ioannis , Gillespie David R. H. , Ireland Peter T. , Kingston Robert
Published: September 2008

Detailed measurements of the heat transfer coefficient distributions on the internal surfaces of a novel gas turbine blade cooling configuration were carried out using a transient liquid crystal technique. The cooling geometry, in which a series of racetrack passages are connected to a central plenum, provides high heat transfer coefficients in regions of the blade in good thermal contact with the outer blade surface. The Reynolds number changes along its length because of the ejection of fluid through a series of 19 transfer holes in a staggered arrangement, which are used to connect ceramic cores during the casting process. Heat transfer coefficient distributions on this holes surface are particularly important in the prediction of blade life, as are heat transfer coefficients within the hole. Results at passage inlet Reynolds numbers of 21667, 45596 and 69959 are presented along with in-hole htc distributions at Rehole = 5930, 12479, 19147 and suction ratios of 0.98, 1.31, 2.08, 18.67. All values are engine representative. The results were compared to predictions made using the commercial CFD package Fluent. Characteristic regions of high heat transfer downstream of the transfer holes were observed with enhancement of up to 92% over the Dittus-Boelter level. Within the transfer holes, the average htc level was strongly affected by the crossflow at the hole entrance. Htc levels were low in these short (l/d = 1.5) holes fed from regions of developed boundary layer.
The Use of High Blockage Ribs to Enhance Heat Transfer Coefficient Distributions in a Model of an Integrally Cast Cooling Manifold
Authors: Ieronymidis Ioannis , Gillespie David R. H. , Ireland Peter T. , Kingston Robert
Published: September 2008

In this paper detailed experimental measurements and computational predictions of heat transfer coefficient distributions in a large scale perspex model of a novel integrally cast blade cooling geometry are reported. In a gas turbine blade, the cooling passage investigated is integrally cast into the blade wall, providing good thermal contact with the outer surface of the turbine blade. Flow enters the racetrack passage through the root of the blade and exits to a central plenum through a series of nineteen transfer holes equally spaced in a staggered arrangement across the span of the blade. The Reynolds number changes continuously along the passage length because of the continuous ejection of fluid through a series of 19 transfer holes to the plenum. The smooth passage surface opposite is in closest proximity to the external surface, and this investigation has characterised the heat transfer coefficient on this surface at a range of engine representative inlet Reynolds numbers using a hybrid transient liquid crystal technique. The ability of three different rib configurations to enhance the heat transfer on this surface was also determined. Because the passage at engine scale is necessarily small, the rib height in all cases was 32.5% of the passage height. As the entire passage wetted surface is able to contribute to the blade cooling, and knowledge of the heat transfer coefficient distribution on the holed surfaces is crucial to prediction of blade life, a commercial CFD package, Fluent, was used to predict the heat transfer coefficient distributions on the holed surface, where there was no optical access during these tests. This also allowed investigation of additional rib configurations, and comparison of the pressure penalty associated with each design. The study showed that the turbulator configuration used allows the position and maximum level of heat transfer coefficient enhancement to be chosen by the engine designer. For the configurations tested heat transfer coefficient enhancement of up to 32% and 51% could be achieved on the holed surface and the ribbed surface respectively. For minimum additional pressure drop 45° ribs should be used.
Robust Kalman Filter Thrust Estimation in a Turbofan Engine
Authors: Henriksson Mattias , Ring Dan
Published: September 2008

This article will present that a robust Kalman filter design has a favorable property, when applied on thrust estimation on a low bypass turbofan gas turbine engine, compared to the regular Kalman filter design. This property is a larger operation range in parameters around the linearization point. On the other hand, the robust Kalman filter has marginally lower accuracy at the linearization point. This paper will present a method for describing the uncertainties in the engine model for use in the design of a robust Kalman filter. Both a regular Kalman filter and a robust Kalman filters are evaluated through simulations around a linearization point by using simulations of a nonlinear military turbofan engine.
Passive Shroud Cooling Concepts for HP Turbines: Experimental Investigations
Authors: Kanjirakkad Vasudevan , Thomas Richard , Hodson Howard , Janke Erik , Haselbach Frank , Whitney Chris
Published: September 2008

The cooling of rotor shrouds in the first stage of a high-pressure turbine requires special attention as flatter turbine inlet temperature profiles and more highly loaded blades result in increased thermal and mechanical stresses. The use of film cooling and/or internal convective cooling makes the rotor shroud heavier and oversized, restricting the maximum rotational speed. Alternative methods are therefore sought to achieve improved cooling of the shroud. This paper discusses the low speed experimental investigation of two ‘passive’ cooling concepts known as ‘rail cooling’ and ‘platform cooling’. It has been shown experimentally that the modified cooling method, namely the platform cooling, substantially improves the rotor shroud coolant distribution in the critical areas whilst employing significantly lower amounts of coolant.
Thrust Control for a Turbofan Engine Using Estimation
Authors: Ring Dan , Henriksson Mattias
Published: September 2008

A thrust control concept for a military turbofan engine is evaluated at sea level and static operation. Most of the design is performed in the linear domain and most validations are done by simulations of nonlinear models. The thrust control is included as an add-on to a robust and multivariable control concept. The presented methods are also applicable for control of other estimated properties. The thrust in this concept is estimated from engine measurements and engine control inputs and both a linear and a nonlinear estimator are presented. The simulation results are promising and the design methods are straight forward. For the estimator a Kalman filter is designed and the thrust control loop are simplified to a single input single output system with the estimator included, which allows standard design methods to be applied. For the operating regime the linear designs have also shown to be applicable to the nonlinear system.
Robust Control of a Gas Turbine With Variable Power Offtake
Authors: Mahmood Shahid , Griffin Ian A. , Fleming Peter J.
Published: September 2008

The conventional approach to Rolls-Royce Inverse Model closed loop fuel control is to represent the inverse high-pressure (HP) spool dynamics within the controller. In this paper, the options of configuring the controller to represent either the intermediate (IP) or the low pressure (LP) dynamics of a 3-spool engine are also analysed. Control performance is assessed as the engine is subjected to step changes in power offtake. For each controller, power offtake is extracted from each of the three shafts in turn giving a total of 9 engine/controller configurations. For any given power offtake configuration applied to the engine, the results suggest that the controller based upon LP or IP dynamics offers more robustness measured in terms of phase margins and improved performance with regard to power offtake disturbance rejection.
Effect of Jet Pulsing on Film Cooling: Part 1— Effectiveness and Flowfield Temperature Results
Authors: Coulthard Sarah M. , Volino Ralph J. , Flack Karen A.
Published: September 2008

Pulsed film cooling was studied experimentally to determine its effect on film cooling effectiveness. The film cooling jets were pulsed using solenoid valves in the supply air line. Cases with a single row of cylindrical film cooling holes inclined at 35 degrees to the surface of a flat plate were considered at blowing ratios of 0.25, 0.5, 1.0, and 1.5 for a variety of pulsing frequencies and duty cycles. Temperature measurements were made using an infrared camera, thermocouples, and cold wire anemometry. Hot wire anemometry was used for velocity measurements. The local film cooling effectiveness was calculated based on the measured temperatures and the results were compared to baseline cases with continuous blowing. Phase locked flow temperature fields were determined from cold wire surveys. Pulsing at high frequencies helped to improve film cooling effectiveness in some cases by reducing overall jet liftoff. At lower frequencies, pulsing tended to have the opposite effect. With the present geometry and a steady mainflow, pulsing did not provide an overall benefit. The highest overall effectiveness was achieved with continuous jets and a blowing ratio of 0.5. The present results may prove useful for understanding film cooling behavior in engines, where mainflow unsteadiness causes film cooling jet pulsation.
Challenges, Issues, and Lessons Learned Implementing Prognostics for Propulsion Systems
Authors: Hess Andrew , Frith Peter , Suarez Eva
Published: September 2008

The desire and need for real predictive prognostics capabilities have been around for as long as man has operated complex and expensive machinery. There has been a long history of developing and implementing various degrees of prognostic and predictive useful life remaining capabilities. Stringent Diagnostic, Prognostic, and Health Management capability requirements are being placed on many of the new platform applications. While life usage accounting and fault detection / isolation effectiveness, with low false alarm rates, continue to improve on these new applications; prognostics requirements are even more ambitious and present very significant challenges to the system design teams. Though advanced life prediction and prognostic capabilities are being addressed for many mechanical and electronic systems; there are some unique challenges and issues associated with modern propulsion system applications. This paper will explore some of these design challenges and issues; discuss the various degrees of prognostic capabilities; address potential development methodologies; and draw heavily on lessons learned from previous prognostic development efforts.
Large-Eddy Simulation of a Swirl-Stabilized, Lean Direct Injection Spray Combustor
Authors: Kırtas¸ Mehmet , Patel Nayan , Sankaran Vaidyanathan , Menon Suresh
Published: September 2008

Large-eddy simulation (LES) of a lean-direct injection (LDI) combustor is reported in this paper. The full combustor and all the six swirl vanes are resolved and both cold and reacting flow simulations are performed. Cold flow predictions with LES indicate the presence of a broad central recirculation zone due to vortex breakdown phenomenon near the dump plane and two corner recirculation zones at the top and bottom corner of the combustor. These predicted features compare well with the experimental non-reacting data. Reacting case simulated a liquid Jet-A fuel spray using a Lagrangian approach. A three-step kinetics model that included CO and NO is used for the chemistry. Comparison of mean velocity field predicted in the reacting LES with experiments shows reasonable agreement. Comparison with the non-reacting case shows that the centerline recirculation bubble is shorter but more intense in the reacting case.
Global Energy Market: Past, Present and Future
Authors: Bhargava R. K.
Published: September 2008

The three fossil fuels, coal, oil and natural gas, are the major and depletable energy resources of the world. By end of the twentieth century, approximately 85% of the total primary energy consumed globally came from the three fossil fuels. In the last two years or so oil prices have almost doubled, whereas, price of natural gas has also increased at a faster rate. Indications and predictions are that these prices will stay for years to come because of imbalance in supply and demand and political instability in the Middle East and Africa regions. In such a dynamic energy market, companies dealing with energy resources, energy related equipment suppliers and service providers will face a stiffer competition. This paper provides a comprehensive overview of the global energy market emphasizing the following key issues: the status of proven fossil fuels reserves which are recoverable with the today’s technology; trends of production and consumption of major fuels; trends of electric power generation and industrial gas turbine market for power generation; and emissions related issues. A brief discussion on gas monetization and IGCC (Integrated Gasification and Combined Cycle) technology is also included. In addition to presenting an in-depth analysis of the energy related data for the last 2–3 decades, projections are provided for the next two decades (until 2025). The presented data will be useful in identifying world’s areas and countries where potentials for energy related businesses are expected to grow in the coming years. The presented study is a timely topic of discussion in presence of a highly volatile energy market and companion to the theme of the Turbo Expo 2006 “The Global Market and Cooperative Ventures”.
A Slow-Speed Rotating Test Facility for Characterising the Stiffness of Brush Seals
Authors: Franceschini Gervas , Morgan Jonathan J. , Jones Terry V. , Gillespie David R. H.
Published: September 2008

An appreciation of the importance of bristle stiffening and hysteresis in brush seals has led to the development of a test facility capable of making stiffness measurements at different seal pressures. Engine scale seals are tested under engine representative differential pressures and eccentric movements in the test facility. To cover current and future sealing requirements the facility is capable of up to 12,5 bar differential pressures across the seal and eccentric rotor to casing movements of 2,5 mm. A slow-speed rotating rotor allows the dynamic friction directions of the contacting seal elements to be matched with the engine application. Both the eccentric cycle through which the seal is driven and the low-speed rotation of the central shaft are computer controlled to ensure known conditions are obtained and experimental repeatability. It has not been necessary to simulate engine temperatures, rotor speeds and radial growth between the engine and test facility. In this paper the test facility is fully described. Experimental results, showing torque, flow and stiffness characteristics from a typical prototype engine brush seal are reported, with full details of the experimental uncertainties. The effects of bristle stiffening, seal hysteresis, and bristle blow-down on the quantities above are detailed in the results.
The Use of Biogas in Internal Combustion Engines: A Review
Authors: Mustafi Nirendra N. , Raine Robert R. , Bansal Pradeep K.
Published: September 2008

Biogas derived from organic waste materials is a promising alternative and renewable gaseous fuel for internal combustion (IC) engines and could substitute for conventional fossil fuels. The aims of this study are to review the past researches on biogas fuelled IC engines and from this review, to identify current research needs. A detailed analysis of the previous results of biogas fueling on the emissions and performance of spark ignition (SI) and dual fuel compression ignition (CI) engines is presented. The literature review reveals that the published research on biogas fueled IC engines are not rich in number and the scenario of biogas-diesel dual fuel engines is even worse. According to the analysis, biogas fueling in IC engines causes lower power output compared to natural gas, irrespective of the engine operating conditions. However, the use of biogas allows exhaust nitrogen oxides (NOx) emissions to be reduced substantially. Both experimental and computational analyses have been done in the case of SI engines. However, there are needs to investigate the exhaust emissions for the biogas-diesel dual fuel engines both experimentally and computationally. Also the effect of H2S on engine emissions and life/durability, which is neglected very often in the literature, needs to be investigated.
The Geislinger Steel Spring Coupling to Lower Torsional Vibrations
Authors: Ro¨ßler D. I. Franz
Published: September 2008

Steel spring couplings for applications such as drive lines, gear drives etc. are installed between two shafts to transmit torque from one shaft to another while influencing the torsional vibrations and accommodating misalignments between the shafts. The main focus is to control the torsional vibrations both by moving the critical resonances out of the operating speed range and damping the remaining vibrations to acceptable levels. The market offers various coupling designs, one of them is the Geislinger Steel Spring Coupling. The stiffness of the coupling leaf springs can be precisely tuned to isolate or move harmful natural resonance frequencies. In addition Geislinger Couplings provide a unique hydrodynamic damping via oil displacement, which effectively absorbs torsional vibrations. The Steel Spring Coupling concept meets not only the demands of any type and size of internal combustion engine, but also the demands of a variety of other machinery systems. Applications for pumps and compressors are typical ones. This paper will present design features, analysis parameters as well as examples of actual applications in order to show how the coupling design is able to meet the torsional requirements.
Effect of Blower and Injector Cutout on Performance and Emissions of an EMD 16-645E Engine
Authors: Hedrick John C. , Fritz Steven G. , Stewart Ted E.
Published: September 2008

The 1,500 kW EMD 16-645E engine is popular in switcher and shunter locomotive applications for railroads in North America. These locomotives are typically lightly loaded with extended periods of idle operation, and usually operate in large urban areas. With the advent of EPA emissions standards, and increasing fuel costs, many in the railroad industry are looking at replacing these locomotives with hybrid locomotives, installing APU systems or automatic start stops systems, repowering with newer engines, or using new technology to reduce emissions and improve fuel consumption. This paper documents results of research into ways to improve idle and low power emissions and fuel consumption from these roots-blown two-cycle EMD 645E engines. Specifically, this research looked at disabling one bank of injectors to simulate skip fire operation, and the stopping the rotation of one of the two roots-type blowers used to supply boost air to the uni-flow, two-cycle, diesel engine. The results of this work demonstrated that the EMD 16-645E engine did not respond positively when the injectors of one cylinder bank were disabled (simulating bank to bank skip fire operation). However, the engine did demonstrate both a reduction of NOx emissions and brake specific fuel consumption, over the US-EPA switcher and line haul emissions cycles, while operating on only one of the two blowers at idle and light loads. Additionally this concept of blower cut-out allows for reduced mass flow and higher exhaust temperatures at light loads, which could be beneficial for future application of exhaust aftertreatment. However, there is an associated increase in particulate matter emissions.
NOx Emissions Reduction of a Natural Gas SI Engine Under Lean Conditions: Comparison of the EGR and RGR Concepts
Authors: Le Corre Olivier , Pirotais Fre´de´ric
Published: September 2008

In natural gas SI engines under lean conditions, NOx emissions reduction can be realized by injecting an additional mass flow rate to inlet gases. It can be easily done in situ using two techniques: EGR (Exhaust Gas Recirculation) or RGR (Reformed Gas Recirculation) which is an improvement of the usual EGR configuration. Exhaust gases are catalyzed before being reintroduced at the engine inlet. Reformed gases contain carbon monoxide and hydrogen in addition to carbon dioxide, steam and nitrogen dioxide that compose usual recirculated gases. In order to compare EGR and RGR concepts, the study is divided in three stages. Firstly, a “two-zone” thermodynamic model has been developed and validated on a large open chamber SI engine (18L CHP plant engine, fuelled by natural gas and equipped with data acquisition). Both in-cylinder pressure and NOx emissions have been compared between numerical results and experimental data. A good agreement is obtained, the error is less than 3%. Secondly, a widespread model of steam reforming on a Ni/MgOAl2O3 catalyst has been used to compute in particular CO and H2 concentrations. Numerical results lead to a good concordance with experimental data from literature. Finally, SI engine and reformer models have been linked. RGR and EGR configurations have been numerically compared considering the same recirculation mass flow rate. According to the results, RGR is the best way to decrease significantly nitrous oxide emissions, while keeping good engine performance.
An Analysis of Ring Temperature, Oil Film Temperature, Oil Film Thickness and Heat Transfer on a Piston Ring of an IC Engine in Consideration of Ring Movement in a Cycle
Authors: Ishijima Takashi , Shimada Akiko , Harigaya Yasuo , Suzuki Michiyoshi , Takiguchi Masaaki
Published: September 2008

An unsteady and two-dimensional thermohydrodynamic lubrication model in consideration of the ring movement and the heat flow from ring groove to piston ring was developed. The piston ring temperature in an internal combustion engine was analyzed by using the unsteady and two-dimensional form heat-conduction equation in consideration of axial movement of ring and heat flow from ring groove to ring during a cycle. The oil film temperature, oil film thickness and heat transfer between ring and liner surfaces were analyzed by using the calculated ring temperature taking into consideration cycle variation. The results are as follows. The heat flow rate around ring changes greatly with the ring movement and the ring sliding face temperature changes about 6 °C in a cycle. Then, the cycle mean temperature of ring sliding face becomes lower than the ring sliding face temperature calculated by the ring groove and liner surface temperatures under 2800 rpm and full load conditions. Therefore, the oil film viscosity is higher than that of the conventional viscosity model in which the viscosity was based on a constant ring sliding face temperature in a cycle. The oil film thickness predicted by the present method is thicker than that calculated by our previous method.
Correlation of Single-Cylinder to Multi-Cylinder Performance for a Medium Speed Diesel Engine
Authors: Topinka Jennifer A. , Hibshman Joell R. , Glenn W. Douglas
Published: September 2008

Single-cylinder research engines are valuable tools in the development of multi-cylinder reciprocating engines. The financial advantages of single-cylinder testing increases with engine size offering even larger benefits for medium-speed engines than light-duty automotive or heavy-duty truck engines. While testing on a single-cylinder engine provides a number of economic and technical advantages [1], careful planning and setup are required to maximize the usefulness of single-cylinder results as predictive of multi-cylinder performance. This paper describes the methodology used to set up and operate a single-cylinder medium speed diesel engine for combustion performance testing. An overview of the test cell design, infrastructure and instrumentation is provided, along with detailed specifications of the engine. There is good correlation between the single-cylinder and multi-cylinder performance when the gas-exchange-and frictional loss differences are taken into account. The strategy and results for this correlation effort are presented and discussed. The apparent rate of heat release was very consistent between the MCE and the SCE for the same load and injection timing. For other parameters, it was found that the single-cylinder engine contains biases relative to the absolute values observed from a full multi-cylinder engine, but the single-cylinder results are very useful in identifying relative performance trends and in performing in-cylinder optimization.
An Experimental Analysis of Flow Through Annular Diffuser With and Without Struts
Authors: Prakash R. , Sudhakar P. , Mahalakshmi N. V.
Published: September 2008

This paper presents the static pressure development and the effect of struts on the performance of an annular diffuser. A typical exhaust diffuser of an industrial gas turbine is annular with structural members, called struts, which extend radially from the inner to the outer annulus wall. An annular diffuser model, primarily intended for fundamental research, has been tested on a wind tunnel. Similar conditions that prevail in an industrial gas turbine have been generated in the diffuser. Measurements were made using a five holed Pitot probe. The research had been carried out to make a detailed investigation on the effect of struts and to advance computational and design tools for gas turbine exhaust diffusers.
Numerical-Experimental Study and Solutions to Reduce the Dwell Time Threshold for Fusion-Free Consecutive Injections in a Multijet Solenoid-Type C.R. System
Authors: Catania Andrea Emilio , Ferrari Alessandro , Spessa Ezio
Published: September 2008

In ‘Multijet’ Common Rail (C.R.) diesel injection systems, when two consecutive injection current-pulses are approached to each other, the fusion of the two injections can occur. This causes undesired excessive amount of injected fuel, which leads to worsening of particulate emissions and fuel consumption. In order to avoid such a phenomenon, lower limits to the values of dwell time are introduced in the control unit maps, by means of a conservatively overestimated threshold, limiting the flexible management of multiple injections and C.R. system capability to perform a larger number of injection shots. The reason of the injection fusion is mainly due to the time delay between the electrical signal to the solenoid and the needle lift at both valve opening and closure. In particular, the dwell-time range inside of which injection fusion occurs was shown to decrease by reducing the nozzle closure delay. Experimental tests were carried out on a high-performance Moehwald-Bosch MEP2000/CA4000 test bench for determining the functional dependence of nozzle closure and opening delays on solenoid energizing time and nominal rail pressure. Besides, a mathematical relation between the solenoid energizing time and the injection time interval was determined. A Multijet C.R. injection system mathematical model, that was previously developed, including thermodynamics of liquids, fluid dynamics, subsystem mechanics, and electromagnetism equations, was applied to better understand the cause and effect relationships for nozzle opening and closure delays. In particular, numerical results on the time histories of delivery- and control-chamber pressures, pilot- and needle-valve lifts, mass flow rates through Z and A holes, were obtained and analyzed in order to highlight the dependence of nozzle opening and closure delays on electro-injector internal geometric features and on the needle dynamics. For all the considered operating conditions, the model predictions were compared to the experimental injection flow-rate patterns and to the pressure data taken at the injector inlet, for assessment. The nozzle closure delay was shown to strongly depend on the needle dynamics. Parametric tests were carried out with the numerical code by changing needle and control plunger mass, needle spring preload and stiffness, maximum needle stroke, in order to identify configurations useful for minimizing the nozzle closure delay. On the basis of the indications derived from these numerical tests, a modified version of the commercial electro-injector was realized so as to achieve effectively reduced nozzle closure delays and very close sequential injections without any fusion between them.
Application of an Improved Model for the Determination of Acoustic Resonances in Indicator Passages for Combustion Pressure Measurements
Authors: Gosweiller Christoph , Willson Bryan , Walter Thomas
Published: September 2008

The acoustic resonances in indicator passages are often modeled using either a Helmholtz or a so called organ pipe acoustical model. However, in practice these models often indicate natural frequencies which are too high. This paper proposes the Bergh and Tijdeman model [1] which is more accurate and which was originally developed for pressure measurements in turbomachinery. This paper presents the theoretical basis for the Berg / Tijdeman model and then uses it to explore signal distortion from a variety of indicator passage geometries. In order to validate the approach, a flush-mounted water-cooled Kistler reference transducer was used to measure accurate in-cylinder combustion data in an automotive Diesel engine. An additional sensor was recess mounted with passages of different geometries. The Bergh Tijdeman model was then applied to investigate the acoustic distortion of the indicator passages. The results show excellent agreement with the experimental data, which are much closer than using the Helmholtz or the organ pipe model. Further the Bergh and Tijdeman model is applied to complex indicator passage geometries with multiple cavities. Again, for comparison, a flush-mounted Kistler reference transducer was used to measure accurate in-cylinder combustion data in a large-bore natural gas engine. Three additional sensors were mounted using different indicator passage geometries. The engine was operated under base line and knocking combustion conditions. The Bergh Tijdeman model was then applied to model the acoustic distortion of the three indicator passages and again showed good agreement with the experimental data. Finally, the paper proposes simple rules for implementing indicator passages in large gas engines.
Combustion Characteristics of Rice Bran Oil Derived Biodiesel in a Transportation Diesel Engine
Authors: Sinha Shailendra , Agarwal Avinash Kumar
Published: September 2008

The methyl esters of vegetable oils, known as biodiesel are becoming increasingly popular because of their low environmental impact and potential as a green alternative fuel for diesel engines. They do not require significant modification in existing engine hardware. Methyl ester of rice bran oil (ROME) is prepared through the process of transesterification. Previous research has shown that ROME has comparable performance, lower bsfc in comparison to diesel. There was reduction in the emissions of CO, HC, and smoke but NOx emissions increased. In the present research, experimental investigations have been carried out to examine the combustion characteristics of a direct injection transportation diesel engine running with diesel, and 20% blend of ROME with diesel. A four-stroke, four-cylinder, direct-injection transportation diesel engine (MDI 3000) was fully instrumented for the measurement of combustion pressure, rate of pressure rise and other combustion parameters such as instantaneous heat release rate, cumulative heat release rate, mass fraction burned etc. Tests were performed at different loads ranging from no load to 100%, at constant engine speed. No engine hardware modification was carried out for the present study. A careful analysis of combustion and heat release parameters has been carried out, which gives precise information about the in-cylinder combustion of rice bran oil based biodiesel vis-a`-vis mineral diesel.
Optical Analysis and Simulation of Diesel Sprays in a High Pressure and High Temperature Spray Box
Authors: Fimml Wolfgang , Fuchs Christian , Jauk Thomas , Wimmer Andreas
Published: September 2008

The characterization of diesel sprays for the simulation-based optimization of injection strategies and combustion chamber geometries is of particular importance to reach future targets concerning performance, fuel consumption and emissions. The prediction quality of this simulation process depends largely upon the adequate calibration of the spray models used. This paper aims to present the experimental setup of a spray box, the applied optical visualization techniques and the results. Furthermore, it will show the adjustment and the validation of the simulation models based on the experimental analysis.
Fuzzy Controller Without Feed-Forward for the Air System of a Diesel Engine
Authors: Arnold J. F. , Tremouliere G. , Langlois N. , Chafouk H.
Published: September 2008

A new strategy based on a fuzzy multi-variable controller is proposed to regulate both the fresh airflow and the intake manifold pressure. The air system controller requires neither an internal model nor certain feed-forward maps. Taking only into account standard engine measurements, it is intrinsically robust and very easy to tune with respect to strategies proposed in literature. The results obtained with this controller are compared to those of current embedded controllers.
Laser Spark Ignition of a Blended Hydrogen-Natural Gas Fueled Single Cylinder Engine
Authors: Richardson Steven W. , McMillian Michael H. , Woodruff Steven D. , Worstell Todd , McIntyre Dustin L.
Published: September 2008

Charge dilution, due to the reduced combustion temperatures that it brings about, has long been proven as effective means of reducing Nitrogen Oxides (NOx) emissions in reciprocating engines. The extent of this dilution is practically bounded on the lean side of stoichiometric conditions by engine misfire or the point at which the combustion process is no longer sufficiently reliable to sustain engine operation within some specified limit. Extending this misfire limit of an engine becomes a worth while goal as it brings about further reductions in NOx emissions. Much work has been dedicated to reaching this end and several techniques have proven viable in natural gas fueled engines. This work explores potential synergies between two proven techniques for NOx reductions in lean-burn natural gas fueled engines, hydrogen enrichment of the natural gas fuel and application of laser spark ignition. Independently both techniques have been shown to provide significant NOx emissions reductions through lean limit extension in spark ignited gaseous fueled reciprocating engines [1–11, 13–15]. Here hydrogen is blended with natural gas at five different levels ranging from 0% to 40% by volume in a single cylinder engine. The mixtures are fired using a conventional spark plug based ignition system and then again with an open beam path laser induced breakdown spark ignition system. NOx emissions measurements were made at different levels including misfire conditions for each level of hydrogen enrichment with both ignition systems. Data are presented and the emissions and engine performance of two configurations are compared to determine realizable benefits that arise from combining the two techniques.
Hydrogen-Enhanced Gasoline Stratified Combustion in SI-DI Engines
Authors: Conte Enrico , Boulouchos Konstantinos
Published: September 2008

Experimental investigations were carried out to assess the use of hydrogen in a Gasoline Direct Injection (GDI) engine. Injection of small amounts of hydrogen (up to 27% on energy basis) in the intake port creates a reactive homogeneous background for the direct injection of gasoline in the cylinder. In this way, it is possible to operate the engine with high EGR rates and, in certain conditions, to delay the ignition timing as compared to standard GDI operation, in order to reduce NOx and HC emissions to very low levels and possibly soot emissions. The results confirmed that high EGR rates can be achieved and NOx and HC emissions reduced, showed significant advantage in terms of combustion efficiency and gave unexpected results relative to the delaying of ignition, which only partly confirmed the expected behavior. A realistic application would make use of hydrogen-containing reformer gas produced on board the vehicle, but safety restrictions did not allow using carbon monoxide in the test facility. Thus pure hydrogen was used for a best-case investigation. The expected difference in the use of the two gases is briefly discussed.
Modeling of Mixed Lubrication Conditions in a Heavy Duty Piston Pin Joint
Authors: Fridman Vladimir , Piraner Ilya , Clark Kent
Published: September 2008

A piston pin joint in a modern diesel engine operates under extreme loading and lubrication conditions. High load in combination with low relative surface velocities and limited lubrication makes this joint prone to localized wear and sudden failure. The analysis of this joint is also complicated with the pin motion, which defines surface velocities in the pin bore to pin and the pin to connecting rod interfaces. Therefore, the entire joint needs to be analyzed as a system of two bearings. Also, the hydrodynamic pressure in this joint at times may not be sufficient to balance the force applied to the joint and has to be complemented by the asperity contact pressure. The latter causes an additional deformation of the bearing. To address this problem a mixed lubrication model has been developed based on spectral EHD and nonlinear Greenwood and Trip statistical asperity contact formulation. Contact pressure distributions calculated with this model showed a pattern similar to the wear pattern in the bushing after production test. Analysis of the heat generated in the bearing was found to be a good indicator for the severity of the regime. Analysis of the bushing and piston bore with different geometry showed that asperity contact pressure and heat generated in the joint can be significantly reduced by modifications in local shape of the contacting surfaces.
The Effect of Engine Exhaust Temperature Modulations on the Performance of Automotive Catalytic Converters
Authors: Shamim Tariq
Published: September 2008

This paper presents a computational investigation of the effect of exhaust temperature modulations on an automotive catalytic converter. The objective is to develop a better fundamental understanding of the converter’s performance under transient driving conditions. Such an understanding will be beneficial in devising improved emission control methodologies. The study employs a single-channel based, one-dimensional, non-adiabatic model. The transient conditions are imposed by varying the exhaust gas temperature sinusoidally. The results show that temperature 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 operating conditions and the modulating gas composition and flow rates (space velocity) have substantial influence on catalyst behavior.
Coupling Codes for Nozzle Flow Modelling in Diesel Injection System
Authors: Chiavola O. , Palmieri F.
Published: September 2008

This paper deals with a numerical investigation of a single cylinder diesel engine equipped with mechanical fuel direct injection system and focuses on the fuel injection system modelling with the aim of predicting the performance of the entire injection system, the spray characteristics, the interaction among spray-cones, combustion chamber flows and geometry. In the simulations, two different codes have been used. With the former one, AMESim code, the complete injection system has been analysed and the single components have been selected and modelled. The results obtained from the injection system simulation, in terms of injection needle lift, injection flow rate, pressure time evolution, have been used to initialize the latter computation tool, FIRE code, in which 3D flow numerical investigation of the internal injector flow has been performed. Since such a flow is directly linked to the spray modelling, the primary break-up effects have been taken into account. The details of the adopted modelling strategy have been shown and the results of each simulation step have been presented. In order to highlight the relationship among the nozzle flow condition and the spray formation-vaporization characteristics, a comparison between two different calculation setups has been shown. Moreover, a qualitative comparison among predictions and experimental data has been discussed.
Numerical Simulation of Soot Deposition in Diesel Particulate Filters
Authors: Chiavola O. , Falcucci G.
Published: September 2008

The present work treats the problems and phenomena related to the soot deposition inside a modern Diesel particulate filter, in order to realize a numerical model able to analyze how particulate matter lays down and grows over the porous walls inside a non-catalyzed diesel particulate filter. The geometry of a commercial device has been imported in a 3D CFD code and the phenomena related to the fluid while it passes through the porous media of the filter have been viewed upon with an unsteady approach for different values of engine power and torque. The obtained velocity fields have been used to calculate the profile of deposited soot after a chosen operation period and the geometry of the filter has been then refreshed for the subsequent quasi-steady simulation. The backpressure due to the growing of the soot layer has been calculated.
Solutions for Improving Spark Plug Life in High Efficiency, High Power Density, Natural Gas Engines
Authors: McCoole Maria-Emmanuella , Tozzi Luigi , Tribble Daniel L.
Published: September 2008

Short spark plug life, resulting in increased engine downtime and operating costs, is the primary factor limiting the power density and thermal efficiency in lean burn natural gas engines. Fundamentally, as engine power density increases, spark plug life decreases. Common approaches to increasing spark plug life include use of high melting temperature electrode materials and increased electrode surface area. However, future targets for engine efficiency and power density require more effective system solutions. In order to achieve these system solutions, work has been focused on developing an empirically derived electrode erosion model. This model quantifies spark plug life as a function of spark discharge characteristics, spark plug electrode design, and flow fields in the vicinity of the spark plug gap for different engine power densities. Furthermore, quenching effects resulting from large surface electrodes and smaller spark gaps have been included to verify ignitability for given in-cylinder charge density and air/fuel ratio conditions. A good agreement between experimental data and model predictions has been demonstrated. Finally, a solution for extending spark plug life in high efficiency, high power density, natural gas engines has been proposed. This solution combines high spark power with a spark plug design consisting of small electrode gap, large electrode surface, and with enhanced flow fields at the electrode gap.
Low Noise Engine Development
Authors: Alt Norbert , Steffens Christoph , Nussmann Christof
Published: September 2008

Nowadays power trains face an increased customer expectation regarding noise and vibration. This trend requires the use of simulation tools beginning in early phases of the development process to ensure a ‘low noise engine’ at the end of the development process. Therefore FEV is using virtual development methods for NVH optimization of power trains for more than ten years. Fully parameterized simulation models allow the utilization in all phases of the development. Depending on the current design status of the development the detailing of the simulation models can be adapted. Based on comparative simple rigid body models in the beginning decisions regarding engine global data like bore, stroke cylinder distance and positioning of balancer shafts can be made. Later on, when more design parameters are fixed the depth of simulation models is increased until a fully flexible model allows the prediction of the NVH behavior of the complete power train. Such a simulation is performed using a hybrid simulation approach based on Finite-Element and Multi-Body simulation. The FE model of the power train is loaded with excitation forces calculated with MBS in order to calculate surface velocity. Based on these results further simulation allows the simulation of the airborne noise radiation. Here, the simulated airborne noise simulation is combined with the so called virtual interior noise simulation (VINS) developed by FEV. This method allows a target-oriented engine development with focus on an excellent vehicle interior noise behavior. Within the scope of this paper the above described procedure is applied to a development of a gasoline inline four cylinder engine. The simulation methods are verified in each step of the development.
Virtual Cooling System Development
Authors: Barthel Ralf , Dohmen Ju¨rgen
Published: September 2008

The cooling system of today’s engines has to fulfill certain requirements which results from fuel consumption reduction, efficiency increase and tightened emission legislation. Additionally the warm-up behavior especially of the passenger cabin and the resulting heater performance requirement leads to controversial targets. Beside these aspects the main function of the cooling system, the limitation of fluid and material temperatures has to be guaranteed. Following the trend that one engine will be integrated in a few different vehicles, with different vehicle-sided cooling system components, the cooling system development gets more and more complex with the result of an increase of the necessary testing effort to develop the system to series status. With focus on this trend, FEV has extended the well proven 1-dimensional thermal management simulation model to a complete closed loop development approach starting from the engine internal coolant flow distribution in the early engine concept phase up to the virtual testing model, which allows to simulate common vehicle test rows on the climate chamber or at hot ambient conditions at rod tests.