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Technical Paper

Comparison of Numerical and System Dynamics Methods for Modeling Wave Propagation in the Intake Manifold of a Single-Cylinder Engine

The automotive industry is striving to adopt model-based engine design and optimization procedures to reduce development time and costs. In this scenario, first-principles gas dynamic models predicting the mass, energy and momentum transport in the engine air path system with high accuracy and low computation effort are extremely important today for performance prediction, optimization and cylinder charge estimation and control. This paper presents a comparative study of two different modeling approaches to predict the one-dimensional unsteady compressible flow in the engine air path system. The first approach is based on a quasi-3D finite volume method, which relies on a geometrical reconstruction of the calculation domain using networks of zero-dimensional elements. The second approach is based on a model-order reduction procedure that projects the nonlinear hyperbolic partial differential equations describing the 1D unsteady flow in engine manifolds onto a predefined basis.
Technical Paper

Multi-Dimensional Modeling of Gas Exchange and Fuel-Air Mixing Processes in a Direct-Injection, Gas Fueled Engine

Direct-injection technology represents today a very interesting solution to the typical problems that are generally encountered in SI, gas-fueled engines such as reduced volumetric efficiency, backfire and knock. However, development of suitable injection systems and combustion chamber geometry is necessary to optimize the fuel-air mixing and combustion processes. To this end, CFD models are widely applied even if the influence of the mesh structure, numerical and turbulence models on the computed results are still matter of investigation. In this work, a numerical methodology for the simulation of the gas exchange and injection processes in gas-fueled engines was developed within the Lib-ICE framework, which is a set of libraries and applications for IC engine modeling developed using the OpenFOAM® technology. The gas exchange and fuel injection processes were simulated into a four-valve, pent-roof hydrogen-fueled engine with optical access.
Technical Paper

Development of Fully-Automatic Parallel Algorithms for Mesh Handling in the OpenFOAM®-2.2.x Technology

The current development to set up an automatic procedure for automatic mesh generation and automatic mesh motion for internal combustion engine simulation in OpenFOAM®-2.2.x is here described. In order to automatically generate high-quality meshes of cylinder geometries, some technical issues need to be addressed: 1) automatic mesh generation should be able to control anisotropy and directionality of the grid; 2) during piston and valve motion, cells and faces must be introduced and removed without varying the overall area and volume of the cells, to avoid conservation errors. In particular, interpolation between discrete fields is frequent in computational physics: the use of adaptive and non-conformal meshes necessitates the interpolation of fields between different mesh regions. Interpolation problems also arise in areas such as model coupling, model initialization and visualisation.
Technical Paper

Direct Evaluation of Turbine Isentropic Efficiency in Turbochargers: CFD Assisted Design of an Innovative Measuring Technique

Turbocharging is playing today a fundamental role not only to improve automotive engine performance, but also to reduce fuel consumption and exhaust emissions for both Spark Ignition and Diesel engines. Dedicated experimental investigations on turbochargers are therefore necessary to assess a better understanding of its performance. The availability of experimental information on turbocharger steady flow performance is an essential requirement to optimize the engine-turbocharger matching, which is usually achieved by means of simulation models. This aspect is even more important when referred to the turbine efficiency, since its swallowing capacity can be accurately evaluated through the measurement of mass flow rate, inlet temperature and pressure ratio across the machine.
Technical Paper

Numerical Investigation of PPCI Combustion at Low and High Charge Stratification Levels

Partially premixed compression ignition combustion is one of the low temperature combustion techniques which is being actively investigated. This approach provides a significant reduction of both soot and NOx emissions. Comparing to the homogeneous charge compression ignition mode, PPCI combustion provides better control on ignition timing and noise reduction through air-fuel mixture stratification which lowers heat release rate compared to other advanced combustion modes. In this work, CFD simulations were conducted for a low and a high air-fuel mixture stratification cases on a light-duty optical engine operating in PPCI mode. Such conditions for PRF70 as fuel were experimentally achieved by injection timing and spray targeting at similar thermodynamic conditions.
Technical Paper

The Evolution of Plastics in Automotive Applications

There have been plastics in automobiles almost as long as there have been plastics. This paper deals with plastic molded parts from the 1930’s through 1970. These parts include steering wheels, tail light lenses, knobs, electrical connectors, fasteners, speedometer wheels, distributor caps, water pump impellers, dials, and various decorative ornaments.
Technical Paper

Ball-on-Cylinder Testing for Aviation Fuel Lubricity

Of the many research approaches investigated over the years to measure the lubrication properties of aviation turbine fuels, the Ball-on-Cylinder Lubricity Evaluator (BOCLE) has emerged as the most significant test. BOCLE was originally a lubricant research device modified for low viscosity jet fuel when the Air Force encountered fuel control problems in 1965 with JP-4. It proved to be capable of detecting the presence of additives such as corrosion inhibitors which improve boundary lubrication properties and also the absence of natural lubricity agents in highly refined jet fuel. The Coordinating Research Council carried out several programs to investigate test variables such as cylinder type, humidity control and load. A semi-automated version using Falex test rings has now been commercialized and is being used to test fuels from aircraft experiencing abnormal pump wear and fuel control hang-up.
Technical Paper

Kinetic Modelling Study of Octane Number and Sensitivity of Hydrocarbon Mixtures in CFR Engines

Aim of this work is to present and discuss the possibility and the limits of two zone models for spark-ignition engines using a detailed kinetic scheme for the characterization of the evolution of the air-fuel mixture, while an equilibrium approach is used for the burnt zone. Simple experimental measurements of knocking tendency of different fuels in ideal reactors, such as rapid compression machines and shock tube reactors, cannot be directly used for the analysis of octane numbers and sensitivity of hydrocarbon mixtures. Thus a careful investigation is very useful, not only of the combustion chamber behavior, including the modelling of the turbulent flame front propagation, but also of the fluid dynamic behavior of the intake and exhaust system, accounting for the volumetric efficiency of the engine.
Technical Paper

Effect of Spray-Wall Interaction on Air Entrainment in a Transient Diesel Spray

The influence of spray-wall interaction on air entrainment in an unsteady non-evaporating diesel spray was studied using laser Doppler anemometry. The spray was injected into confined quiescent air at ambient pressure and temperature and made to impact on a flat wall. The air velocity component normal to a cylindrical surface surrounding the spray was measured during the entire injection period, allowing to evaluate the time history of the entrained air mass flow rate. The influence of wall distance and spray impingement angle on air entrainment characteristics has been investigated and the results indicate that the presence of a wall increases the entrained mass flow rate in the region close to the surface, during the main injection period. Normal impingement appears to produce stronger effects than oblique incidence at 30 and 45 deg. A qualitative explanation of the results is also proposed, based on the drop-gas momentum exchange mechanism.
Technical Paper

Experimental Evaluation of Wind Noise Sources: A Case Study

Several of the authors have recently developed procedures to efficiently evaluate experimentally the relative contributions of various wind noise paths and sources. These procedures are described and, as a case study, results are provided for the noise in the interior of a production automobile subjected to wind tunnel airflow. The present measurements and analysis indicate that for the tested vehicle significant contributions to interior noise are provided by underbody and wheel well flows, radiation from the roof and seal aspiration. A significant tone associated with vortex shedding from the radio antenna was also noted.
Technical Paper

Filtration of Coolants for Heavy Duty Engines

Coolant filters have been used for over 30 years by heavy duty engine builders but little has been published in the technical literature documenting their performance. In heavy duty cooling systems a supplemental additive package is periodically added to the system (usually at the oil drain) to prevent the coolant from becoming corrosive and to stop the build-up of deposits which cut down on heat transfer. Not only is the coolant filter the most convenient and reliable method to deliver the supplemental additive to the cooling system, it removes debris from the coolant which can cause deposits and wear, aggrevate corrosion, and even plug heat exchangers. Additionally, the used coolant filter serves as a diagnostic trouble shooting tool. The results of extensive lab and field evaluations are reported documenting the benefits of coolant filtration.
Technical Paper

Diesel Fumigation Partial Premixing for Reducing Ignition Delay and Amplitude of Pressure Fluctuations

The results of an experimental study in a DI Diesel engine are presented which shows that partial premixing, using direct diesel fumigation of the inlet air, achieved a reduction in the ignition delay, the magnitude of high frequency rapid pressure fluctuations, the maximum rate of pressure rise and the amplitude of the rate of the high frequency pressure oscillations. Two methods of diesel fumigation were investigated. The difference between these two methods was the degree of premixing of diesel fuel with the inlet air. The first technique used a fine (5 micron) diesel spray onto a glow plug and the second technique used prevaporised diesel. A Perkins 4-236 engine was run both with and without fumigation at two different steady state speeds roughly covering both city and highway running conditions.
Journal Article

Brake Based Torque Vectoring for Sport Vehicle Performance Improvement

The most common automotive drivelines transmit the engine torque to the driven axle through a differential. Semi-active versions of this device ([4], [5], [6]) have been recently conceived to improve vehicle handling at limit and under particular conditions; these differentials are based on the structural scheme of the passive one but they try to manipulate the vehicle dynamics by controlling the distribution of the driving torque on the wheels of the same axle thus generating a yaw moment. Unfortunately a semi-active differential is not able to perform a complete yaw control since the torque can only be transferred from the faster wheel to the slower one; on the other hand, active differentials ([11], [12], [13]) allow to generate the most appropriate yaw moment controlling both the amount of transferred torque and its direction.
Technical Paper

A Comparative Study of Automotive Side Window Occupant Containment Characteristics for Tempered and Laminated Glass

This study investigates occupant containment characteristics of tempered and laminated automotive moveable side glass in rollover collisions. FMVSS 216 test protocols were used to induce roof damage or sheet metal damage around the window opening in Lincoln Navigators equipped with tempered and laminated side glass. Dummy-drop tests were then performed to investigate relative containment. The results demonstrate that, for rollovers in which the window structure is compromised, tempered side glass and laminated side glass perform comparably relative to occupant containment. Also discussed are the general strength characteristics of different types of glass construction, the availability of laminated side glass in recent model U.S. vehicles, and anecdotal data supporting the conclusions of testing.
Technical Paper

The Hydrocycle Rocket Free-Piston Instant-Conversion Adiabatic Engine and One-Range, Infinitely Variable Hydrostatic Transmission System

The ideal internal-combustion crankshaft engine would burn all the fuel near top center without detonation, then expand the whole charge until exhaust Both events are impossible with current piston engines. The Hydrocycle Rocket Piston Engine concept employs a free piston in the head of a two-stroke-cycle engine. Combustion between the crank piston and the free piston allows direct conversion of combustion fluid expansion to hydrostatic fluid flow and accumulator gas compression with perfect timing and minimum thermal and mechanical losses. An infinitely variable, radial hydrostatic motor gives the driver smooth, gas-cushioned acceleration and stepless performance. Maximum economy is attained since the driver is forced to run the engine at optimum minimum speed to match road load oadin all traffic conditions.
Technical Paper

Progress in Diesel HCCI Combustion Within the European SPACE LIGHT Project

The purpose of the European « SPACE LIGHT » (Whole SPACE combustion for LIGHT duty diesel vehicles) 3-year project launched in 2001 is to research and develop an innovative Homogeneous internal mixture Charged Compression Ignition (HCCI) for passenger cars diesel engine where the combustion process can take place simultaneously in the whole SPACE of the combustion chamber while providing almost no NOx and particulates emissions. This paper presents the whole project with the main R&D tasks necessary to comply with the industrial and technical objectives of the project. The research approach adopted is briefly described. It is then followed by a detailed description of the most recent progress achieved during the tasks recently undertaken. The methodology adopted starts from the research study of the in-cylinder combustion specifications necessary to achieve HCCI combustion from experimental single cylinder engines testing in premixed charged conditions.
Technical Paper

Future General Aviation Piston Engines and Fuels - An Integrated Approach

The continued availability of leaded specialty aviation gasolines remains as an item of crucial importance in the near-term future of general aviation; however, the development of new piston engines capable of operation with other transportation fuels available in large pools is considered an indispensable element in the long-range survival of the industry. This paper offers a road map that while allowing the continued utilization of the current fleet of piston aircraft, sets the stage for a transition to new piston powerplants and associated aircraft, compatible with widely available transportation fuels such as motor gasoline based aviation fuels for the lower and some medium performance aircraft, and aviation turbine fuels for the balance of medium and high performance airplanes.
Technical Paper

Flame Quenching in the Micro-Chamber Passages of I .C. Engines with Regular-Symmetric Sonex Piston Geometry

Both physical experiments and detailed chemical kinetics studies establish that Sonex micro-chambers imbedded in the walls of the piston bowl of an I.C. engine generate highly reactive intermediate chemical species and radicals- which, when allowed to mix with the fresh charge of the next cycle in the main chamber, substantially alter the chemical kinetics of main chamber combustion. A much more stable overall combustion process is observed, requiring substantially leaner air-fuel ratios than normal, and with much lower ignition temperatures. The net result, without any efficiency penalty, is an engine with an “ultra-clean” exhaust and with a greater tolerance to a wider range of fuels. Crucial to this process is the quenching of the flame in the passages connecting the micro-chambers to the piston bowl. It is flame quenching which enables the incomplete combustion of the charge trapped in the micro-chamber cavities.
Technical Paper

NOx Reduction Kinetics Mechanisms and Radical-Induced Autoignition Potential of EGR in I.C. Engines Using Methanol and Hydrogen

This numerical study examines the chemical-kinetics mechanism responsible for EGR NOx reduction in standard engines. Also, it investigates the feasibility of using EGR alone in hydrogen-air and methanol-air combustion to help generate and retain the same radicals previously found to be responsible for the inducement of the autoignition (in such mixtures) in IC engines with the SONEX Combustion System (SCS) piston micro-chamber. The analysis is based on a detailed chemical kinetics mechanism (for each fuel) that includes NOx production. The mechanism for H-air-NOx combustion makes use of 19 species and 58 reactions while the methanol-air-NOx mechanism is based on the use of 49 species and 227 reactions. It was earlier postulated that the combination of thermal control and charge dilution provided by the EGR produces an alteration in the combustion mechanisms (for both the hydrogen and methanol cases) that lowers peak cycle temperatures-thus greatly reducing the production of NOx.
Technical Paper

Design and Evaluation of the ELEVATE Two-stroke Automotive Engine

ELEVATE (European Low Emission V4 Automotive Two-stroke Engine) was a research project part funded by the European Commission to design and develop a compact and efficient gasoline two-stroke automotive engine. Five partners were involved in the project, IFP (Institut Français Du Pétrole) who were the project leaders, Lotus, Opcon (Autorotor and SEM), Politecnico di Milano and Queen's University Belfast. The general project targets were to achieve Euro 3 emissions compliance without DeNOx catalisation, and a power output of 120 kW at 5000 rev/min with maximum torque of 250 Nm at 2000 rev/min. Specific targets were a 15% reduction in fuel consumption compared to its four-stroke counterpart and a size and weight advantage over the four-stroke diesel with significant reduction in particulate and NOx emissions. This paper describes the design philosophy of the engine as well as the application of the various partner technologies used.