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With the increased interest in the use of ethanol as an alternative fuel to gasoline, Original Equipment Manufacturers (OEMs) have responded by adapting their current range of vehicles to be able to run on gasoline/ethanol blends. Flex fuel vehicles are defined are defined as those that are capable of running gasoline up to 100% ethanol. Other than changes to materials compatibility, to enable the required durability targets to be met when running on ethanol, very little in the way of changes are performed to take advantage of the properties of ethanol. Calibration changes are typically limited to changes in fueling requirements and ignition timing. The physical and chemical properties of ethanol/gasoline blends offer a mixture of advantages and disadvantages. Lower energy density in the form of lower heating value reduces vehicle range whilst higher octane ratings make these excellent fuels for boosted operation.

Both the automotive and truck industry are facing further regulated emissions legislation in the near future. Understanding the emissions and fuel consumption attributes of an engine/vehicle application during a drive cycle early in an engine development program is a critical step to steer the engine development program to a successful final product. The generally accepted approach is to calibrate an engine on a dynamometer and to adjust the operation of the engine to meet performance targets. With the current build and test approach, these adjustments may not be made until well into the development program, and this calibration is a costly and time consuming step in the engine development process.

In order to meet the legislated emissions levels, future diesel engines will likely utilize cooled exhaust gas re-circulation (EGR) to reduce emissions. The addition of the EGR cooler to the conventional vehicle coolant system creates several challenges. Firstly, the engine cooling system flow and heat rejection requirements both increase as it is likely that some EGR will be required at the rated power condition. This adversely affects packaging and fuel economy. The system design is further complicated by the fact that the peak duty of the EGR cooler occurs at part load, low speed conditions, whereas the cooling system is traditionally designed to handle maximum heat duties at the rated power condition of the engine. To address the system design challenges, Ricardo have undertaken an analytical study to evaluate the performance of different cooling system strategies which incorporate EGR coolers.

Tools for the design and evaluation of engine water pumps have been developed. These tools range from textbook calculations to 3-dimensional computational fluid dynamics methods. The choice of the tools or the combination of tools used is usually dependent upon production timelines, rather than technical merit. Therefore, the strengths and weaknesses of each of the tools must be understood, and each tool must be validated for its specific purpose, then used appropriately to aid in the design or development of a water pump suitable for production. This study was carried out to evaluate three approaches: a proprietary Ricardo approach based on 1-dimensional analysis and correlations, a 3-dimensional computational fluid dynamics approach, and a conventional prototype manufacture and test iteration approach. The analytical results were correlated to experimentally obtained pressure rise, mass flow rate, and impeller speed data.

A flow and heat transfer model of an engine lubrication system has been developed in order to predict sump oil temperature and study heat transfer mechanisms within the lubricating oil circuit. The objective was to develop the capability of simulating all the energy transfers between the oil and the combustion process, the engine coolant, and the engine bay air. The model developed in this study simulates a V8 spark ignited engine. Included in this simulation is a bearing model for friction heat generation, a combustion heat input model, and component models for each key heat transfer site in the lubricating oil circuit. The model predicts sump oil temperatures under different engine operating conditions and simulation results were compared to test data with good agreement. The sensitivity of oil temperature to engine speed, engine load, coolant temperature, piston friction, bearing heat energy generation, piston design, water jacket depth, and oil flow rate(s) was studied.

This paper demonstrates the effect of elastic deformation of the cylinder wall on the lubrication between the skirt and cylinder with simulation results of two realistic examples. The simulation methodology is described. Cylinder flexibility caused substantial changes in slap motion, average and peak wear loads on the skirt, friction, and power losses due to asperity contact and hydrodynamic friction. Cylinder deflection due to side loads was about ten percent of the skirt deflection due to side loads, and deformation due to cylinder gas pressure was substantial.

Engine tests were conducted on a production 2.5-liter V-6 engine to investigate the effects of spark plug tip designs on a 4-cycle SI engine of current technology. The data suggest that cyclic variation can increase when the ground electrode faces the primary intake port. Lean-operation limits were extended by the use of J-gap spark plugs as compared to surface-gap and ring-gap spark plugs at the conditions tested. The surface-gap type spark plugs lose some energy as the arc traverses the surface of the insulator. Voltage requirements decrease for reversed polarity at the part load conditions tested but increase at wide open throttle.

AISI-4140H steel has been used as articulated piston crown material in heavy-duty engines. With the driving force for reducing manufacturing cost, microalloyed steel (MAS) was identified as a low-cost material to replace 4140H steel. In order to determine the feasibility of using MAS to replace 4140H steel, a test program was initiated to fully evaluate the material properties of MAS and to compare them to those of the baseline 4140H steel. The physical and mechanical properties of both materials from room temperature to 550°C were evaluated. The effect of long term thermal exposure on the material properties was also studied. Some engine tests were also conducted to evaluate the performance of the articulated pistons made with both materials. The inherently lower strength of MAS as compared to 4140H steel, requires a total re-design of the piston for the utilization of MAS as a low-cost replacement material for 4140H steel.

The NVH characteristics of a modern, aluminum block, V-6 engine were shown to be nearly equivalent when a cast ductile iron crankshaft with multi-mode damper was substituted for the production, forged steel crankshaft with conventional, single torsional mode damper. This result contradicts the traditional thinking that suggests forged steel crankshafts produce better NVH characteristics than ductile iron crankshafts. Also, a lightweight, cast ductile iron crankshaft with multi-mode damper showed only slightly inferior NVH characteristics than the production, forged steel crankshaft with single torsional mode damper. The substitution of cast ductile iron for forged steel can also result in significant cost and weight savings.

This paper discusses a new approach to the finite element analysis of cylinder head gaskets. The new method is based on a feature of the ABAQUS® finite element solver which allows the user complete freedom to define unique material properties. This is an attractive option for cylinder head gasket analysis because the user has the freedom to describe materials which are non-linear and anisotropic. There is also the possibility of specifying independent loading and unloading characteristics. To ensure repeatability and avoid errors, the new method includes a user-friendly program to automate the input deck preparation procedure. In addition to offering new capabilities, the new method was found to converge more quickly than the current gasket analysis method.

A novel mechanism using a moving rocker pivot has been developed by Motive Engineering. The chosen approach offers variation of lift, duration, and phase. A compact, robust proof-of-concept mechanism has been designed, and fabricated. It was fitted to the intake valvetrain of a production SOHC four-cylinder engine. The operation of the mechanism is described. A longer-duration, higher-lift camshaft was designed to explore the potential benefits of the concept throughout the speed and load range. Dynamometer testing has been done to explore possible benefits to power, fuel economy, and exhaust emissions.

A dynamic simulation of a school bus powertrain has been constructed for the purpose of assisting in the development of engine control strategies. With some extensions, this model can also be used as a first approximation to support the development of transmission shift control strategies, predict vehicle performance and drivability as well as estimate transient loads on the powertrain components. The simulation was constructed using the Matlab* computing environment along with the Simulink* toolbox, a package for the graphical development of dynamic simulation models. The vehicle model was validated against test data measured in the target vehicle powered by a natural gas engine to ensure that the simulation model yielded sensible predictions of the dynamic powertrain behavior. Equipped with a validated model, the control engineer can now use the simulation tool to assist in algorithm development. Sample applications are illustrated.

Inter-ring gas pressure and piston ring motion are considered important for the control of oil consumption, particulate emissions, and reduced friction. For this reason, inter-ring gas pressure was measured on a diesel engine. Two different ring pack configurations were tested (positive and negative twist second rings). A significant difference in measured inter-ring pressure was observed. The measurements were compared to the predictions of a cylinder kit model with favorable results. Predictions showed that the observed difference between measured inter-ring pressures is caused by a significant difference in ring motion. The reasons for these differences are explained in this paper.

The paper presents the latest research results on the piston ring free shape. A new free shape measurement method with optical gauging was developed. Three numerical models to compute the contact force distribution of piston ring were developed using finite element analysis (FEA). These numerical methods have been compared each other, and validated with the experimental results of ring deformation in a ring gage. The contact force distribution of a piston ring at working condition was also studied. It consists of the ring thermal boundary conditions (RTBC) validation, 3-D FEA thermal analysis and thermal contact force computation based on validated wire-cable element model. The RTBC for heavy duty diesel engine has been validated for the first time using a CUMMINS L10 engine test. Three different free shapes have been tested. The wear band measurements of tested rings all show tremendous improvements over the standard top ring.

A new telemetry system has been developed for temperature or strain measurements on a spherical joint piston. The system includes a piston mounted signal multiplexer and transmitter. A patented, piston mounted power generator operates in conjunction witii a modified cylinder liner. The telemetry system is robust, having high inertia load capability and high environmental temperature operating capability. The telemetry system was installed and operated on an engine motoring test rig. Temperature signals were transmitted at engine speeds from 400 rpm to 2100 rpm. Over 100 hours of high engine speed testing with oil sump temperatures up to 122°C were completed.

Measurements have been made to determine the effect of piston crown surface properties on combustion. Back-to-back engine tests were conducted to compare surface modified pistons to a production piston. Each modified piston was found to prolong combustion duration. Porous coatings and a non porous, roughened piston were observed to increase fuel consumption. Increase in fuel consumption was determined to be the result of increased heat release duration. The data show surface roughness alone affects the duration of heat release. The shift in magnitude of the centroid of heat release was similar to the shift observed in insulated engine experiments.

Data have been gathered to compare the performance of steel crown pistons coated with yttria stabilized zirconia or mullite to an uncoated piston. The effect of coated pistons on in-cylinder heat transfer was determined from curves of ISFC versus centroid of heat release. Error analysis of the measurements showed uncertainty of ± 3% in ISFC and ± 2 crank angle degrees in the centroid of heat release could be expected for the data. Particulate emissions increased at advanced injection timings with the mullite coated piston while the zirconia coated piston showed an increase in particulate and NOx at advanced timings.

Recent engine design trends towards increasing power, reducing weight, advancing of injection timing and increasing of injection rate and pressure could result in increased incidence of liner pitting. Liner pitting due to coolant cavitation is a complex function of many engine design parameters and operating conditions as described in reference [1]*. Traditionally, liner cavitation problems were not detected early in the development cycle. Traditional liner vibration and coolant pressure measurements in conjunction with a numerous amount of expensive engine endurance tests were then needed to resolve cavitation problems. A method newly developed by the author and described in reference [2] for cavitation intensity measurements was successfully utilized to map out engine operating condition and develop limit curves. This method could also be applied in a non intrusive fashion.

Cavitation corrosion is a very complex phenomenon that is governed by a formidable amount of factors and parameters. The phenomenon is a multi-disciplinary one which involves several aspects of physical sciences and engineering. This process is a slow progressive phenomenon with its detrimental effects being felt after severe damage has already occurred. A real time detection method for the severity of fluid cavitation and bubble collapse is described. The results are correlated to dynamic instantaneous pressure fluctuation measurements. The method is fast, reliable, and less restrictive of the sensing location. It has been tested and verified through a specially designed cavitation test rig and instrumentation setup. The method can be used for cavitation studies on ultrasonic bench rig tests and for cavitation measurements on running engines. The method was used to shed some light on characteristic cavitation differences between water and glycol which is used in engine coolants.

Previous work on the cooling jackets of the Cummins L10 engine revealed flow separation, and low coolant velocities in several critical regions of the cylinder head. The current study involved the use of detailed cooling jacket temperature measurements, and finite element heat transfer analysis to attempt the identification of regions of pure convection, nucleate boiling, and film boiling. Although difficult to detect with certainty, both the measurements and analysis pointed strongly to the presence of nucleate boiling in several regions. Little or no evidence of film boiling was seen, even under very high operating loads. It was thus concluded that the regions of seemingly inadequate coolant flow remained quite effective in controlling cylinder head temperatures. The Cummins L10 upon which this study has focused is an in-line six cylinder, four-stroke direct injection diesel engine, with a displacement of 10 liters.