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When a vehicle with a partially filled fuel tank undergoes sudden acceleration, braking, turning or pitching motion, fuel sloshing is experienced. It is important to establish a CAE methodology to accurately predict slosh phenomenon. Fuel slosh can lead to many failure modes such as noise, erroneous fuel indication, irregular fuel supply at low fuel level and durability issues caused by high impact forces on tank surface and internal parts. This paper summarizes activities carried out by the fuel system team at Ford Motor Company to develop and validate such CAE methodology. In particular two methods are discussed here. The first method is Volume Of Fluid (VOF) based incompressible multiphase Eulerian transient CAE method. The CFD solvers used here are Star CD and Star CCM+. The second method incorporates Fluid-Structure interaction (FSI) using Arbitrary Lagrangian-Eulerian (ALE) formulation.

A new turbocharged 60° 2.7L 4V-V6 gasoline engine has been developed by Ford Motor Company for both pickup trucks and car applications. This engine was code named “Nano” due to its compact size; it features a 4-valves DOHC valvetrain, a CGI cylinder block, an Aluminum ladder, an integrated exhaust manifold and twin turbochargers. The goal of this engine is to deliver 120HP/L, ULEV70 emission, fuel efficiency improvements and leadership level NVH. This paper describes the upfront design and optimization process used for the NVH development of this engine. It showcases the use of analytical tools used to define the critical design features and discusses the NVH performance relative to competitive benchmarks.

The modeling of plastic fuel tank systems for crash safety applications has been very challenging. The major challenges include the prediction of fuel sloshing in high speed impact conditions, the modeling of multilayer thermoplastic fuel tanks with post-forming (non-uniform) material properties, and the modeling of tank straps with pre-tensions. Extensive studies can be found in the literature to improve the prediction of fuel sloshing. However, little research had been conducted to model the post-forming fuel tank and to address the tension between the fuel tank and the tank straps for crash safety simulations. Hoping to help improve the modeling of fuel systems, the authors made the first attempt to tackle these major challenges all at once in this study by dividing the modeling of the fuel tank into eight stages. An ALE (Arbitrary Lagrangian-Eulerian) method was adopted to simulate the interaction between the fuel and the tank.

Until now no results have been available regarding the composition of evaporative emissions in a SHED test. In particular, for alcohol containing fuels, it is important to assess the relative percentage of alcohols and hydrocarbons in view of their different environmental impacts. This paper presents the results of a study conducted to determine the composition of the emissions from a number of multilayer coextruded plastic fuel tanks soaked in IE10 and CM15 test fuels. These emissions were analyzed for composition using a gas chromatography analytical method which employs a vapor trap and desorb sampling technique. In the case of CM15, methanol was found to account for as much as 50% of the overall evaporative emissions. This speciation method also allows estimation of how leakage and permeation contribute separately to the overall emissions.

A simple set of equations has been developed to characterize automotive fuel behavior in fuel tanks, fuel vapor systems and fuel rails, particularly under hot weather conditions. The system of equations links the vapor pressure P, the temperature T, and the mass fraction evaporated Z. Parameters are determined empirically from laboratory vapor pressure and distillation tests. With appropriate values for heat capacity, heat of vaporization, and vapor composition, the equations can be used to estimate upper flammability limits, fuel weathering under hot fuel handling conditions, pressure rise in tanks, and evaporative vapor generation. The equations were developed as part of a larger fuel vapor system model.

The requirements to produce high specific power, a high torque across a broad engine speed range and very low emissions levels have been seen as mutually exclusive in a conventional normally aspirated SI engine. Ford Motor Co in association with Cosworth Technology Ltd. have developed a port injection SI engine which achieves in excess of 63kW/ltr, a peak torque in excess of 97Nm/ltr, 92Nm/ltr between 2500rpm and 6500rpm and meets European IV and North American LEV emissions levels for the Focus ST170 in Europe and the SVT Focus in the US. To achieve the required torque across the speed range the volumetric efficiency needed to be maximized at all engine speeds. This was done by fitting continuously variable inlet valve timing, variable length intake manifold and a tuned exhaust manifold. To meet the emissions requirements, the catalyst light off time must be kept to a minimum.

Validation of the Ford General Engine SIMulation program (GESIM) with measured firing data from a modified single cylinder Ricardo HYDRA research engine is described. GESIM predictions for peak cylinder pressure and burn duration are compared to test results at idle operating conditions over a wide range of valve overlap. The calibration of GESIM was determined using data from only one representative world-wide operating point and left unchanged for the remainder of the study. Valve overlap was varied by as much as 36° from its base setting. In most cases, agreement between model and data was within the accuracy of the measurements. A cycle simulation computer model provides the researcher with an invaluable tool for acquiring insight into the thermodynamic and fluid mechanical processes occurring in the cylinder of an internal combustion engine.

This paper reviews the design and development of a self-filling, in-tank fuel system reservoir intended for use in diesel engine vehicle applications. This new idea eliminates engine driveability concerns (stumbles, hesitations, stalling, etc.) associated with an inconsistent supply of fuel from the fuel tank to the engine, particularly during sudden vehicle maneuvers and with low fuel tank conditions.

Computational fluid dynamics (CFD) simulations of the thermal environment surrounding an underbody fuel tank in a passenger vehicle are presented. In this study, an orthogonally structured full vehicle CFD model was used to provide the necessary boundary conditions for a body-fitted unstructured CFD model of the underbody region containing the fuel tank surface. This method provides a timely approach to performing this type of simulation in support of rapidly changing vehicle development programs. The results for both idle and 30 mph conditions indicate that the major source of external fuel tank heating is the heat convected to the fuel tank surface from the underhood region of the vehicle. Comparisons of simulation results with test data from a similar vehicle shows a good correlation between the two.

A series of tests were conducted to determine the potential for reducing vehicle underhood temperatures by either 1) diverting the radiator fan air flow from the engine compartment or 2) by forced air cooling of the exhaust manifold in conjunction with shielding it or 3) by a combination of the two methods. The test vehicle was a Ford F-250 Light Truck with a 7.5L V-8 engine. The vehicle was tested in a dynamometer cell equipped with cell blowers to simulate road speed conditions. It was found that diverting the outlet air from the radiator will reduce underhood component temperatures when the vehicle is in motion and also at normal idle. However, if the vehicle is to be used for power takeoff applications requiring a “kicked” idle, then forced cooling of the exhaust manifolds is also required to maintain reduced underhood temperatures. A combination of these two techniques maximized the reduction of underhood temperatures for all operating conditions tested.

Evaporative emissions from automotive fuel systems have been recognized as one contributor to photochemical smog and ozone pollution, and so are subject to increasingly stringent regulation. An attractive strategy is to limit the amount of fuel vapor generated in the fuel system, thus easing the burden on the vehicle systems needed to store and eliminate vapor. High fuel tank temperature is a major contributor to vapor generation. Many efforts to reduce the temperature inside a fuel tank have been attempted such as mechanical or electrical returnless fuel systems. Even though these systems reduce vapor generation by about 80% compared to conventional return systems, further improvements may be possible. One way to identify possible improvements is to separately examine the vapor generation of fuel system components, such as fuel pumps, pressure regulators, and jet pumps. Most of these components have an orifice or a narrow flow path which generates low pressure.

A bi-fuel (Compressed Natural Gas [CNG] and gasoline) pickup truck has been developed using the Ford Alternative Fuel Qualified Vehicle Modifier (QVM) process. The base vehicle's 4.9L engine has been specially modified for improved durability on gaseous fuels. The base vehicle's configuration has been designed for conversion to bi-fuel CNG operation. A complete CNG fuel system has been designed and qualified, including fuel tanks, fuel system, and electrical interface. The completed vehicle has been safety and emission certified, demonstrating CARB Low Emission Vehicle (LEV) emissions in MY95. This paper details the design objectives, development process, CNG components, and integration of the two fuel systems.

This paper presents the experience of Ford Motor Company and Hitachi Metals Ltd., in the development and design of the exhaust manifolds for the new 1997 Ford 6.8L, Vl0 gasoline truck engine. Due to the high-exhaust temperature 1000 °C (1832 °F), heat-resisting nodular graphite irons, such as high-silicon molybdenum iron and austenitic iron with nickel cannot meet the durability requirements, mainly thermal fatigue evaluation. The joint effort by both companies include initial manifold design, prototype development, engine simulation bench testing, failure analysis, material selections (ferritic or austenitic cast steel), production processes (casting, machining) and final inspection. This experience can well be applied to the design and development of new cast stainless-steel exhaust manifolds in the future. This is valid due to the fact that US EPA is requiring all car manufacturers to meet the new Bag 6-Emission Standards which will result in increased exhaust gas temperature.

A vehicle's evaporative emission control system is continuously working, even when the vehicle is not running, due to generation of vapors from the fuel tank during ambient temperature variations. Diurnal temperature cycles cause the fuel tank to breathe the fuel vapor in and out, and thus the activated carbon canister is constantly loading and purging the hydrocarbon vapors. This paper discusses a study undertaken at Ford to evaluate the relationship between carbon canister condition and fuel tank vapor generation during diurnal cycles. The results of an extensive set of experiments are presented, and the data from these experiments are compared to the output of a fuel vapor system model also developed at Ford. Key parameters relating to the migration of hydrocarbons during the experimental conditions studied, including initial canister condition, canister volume, and canister geometry, are discussed.

With appropriate signal conditioning, it is possible to estimate Distance-to-Empty utilizing only fuel level and distance sensors. The relationship of speed of response to changing driving conditions and the accuracy of the calculated value is a function of fuel tank/fuel sensor design and driving conditions.

Operation of America's first factory built vehicles modified to operate on natural gas began in April, 1984, when Ford Motor Company delivered the first of 27 specially equipped 1984 Ranger pickup trucks to 25 major utility and natural gas related companies in the United States and Canada. In addition to the fuel system, modifications to these test vehicles include a 12.8:1 compression ratio engine and a unique distributor calibration to provide performance similar to the gasoline powered vehicle. The fuel tanks are significantly more expensive than gasoline tanks and remain one of the major cost issues with a natural gas powered vehicle. There are however, no unresolvable technological issues that would prevent motor vehicles from operating economically and efficiently on natural gas.

Liquid fuels and the fuel vapors in equilibrium with them typically differ in composition. These differences impact automotive fuel systems in several ways. Large compositional differences between liquid and vapor phases affect the composition of species taken up within the evaporative emission control canister, since the canister typically operates far from saturation and doesn't reach equilibrium with the fuel tank. Here we discuss how these differences may be used to diagnose the mode of emission from a sealed container, e.g., a fuel tank. Liquid or vapor leaks lead to particular compositions (reported here) that depend on the fuel components but are independent of the container material. Permeation leads to emissions whose composition depends on the container material. If information on the relative permeation rates of the different fuel components is available, the results given here provide a tool to decide whether leakage or permeation is the dominant mode of emission.

Automotive fuel vapor emissions that would otherwise evaporate into the atmosphere are being captured in activated carbon vapor storage canisters. Fuel vapor is loaded into the canisters via a direct connection to the fuel tank vapor dome. Hydrocarbons are desorbed from the activated carbon into the engine combustion cylinders using engine intake vacuum. The carbon canister capacity requirements have increased in recent years in order to meet both Enhanced Evaporative Emission regulations and the Clean Air Act emission requirements for On-board Refueling Vapor Recovery (ORVR). The higher capacity requirements have generated the need for larger volume canisters that can meet the emission requirements and still be designed within the space and packaging limits of the vehicle application. This paper describes the simultaneous engineering approach used at Ford Motor Company to design a large volume cylindrical shaped carbon canister.

The exhaust blowdown pulse from each cylinder of a multi-cylinder engine propagates through the exhaust manifold and can affect the in-cylinder pressure of other cylinders which have open exhaust valves. Depending on the firing interval between cylinders connected to the same exhaust manifold, this blowdown interference can affect the exhaust stroke pumping work and the exhaust pressure during overlap, which in turn affects the residual fraction in those cylinders. These blowdown interference effects are much greater for a turbocharged engine than for one which is naturally aspirated because the volume of the exhaust manifolds is minimized to improve turbocharger transient response and because the turbines restrict the flow out of the manifolds. The uneven firing order (intervals of 90°-180°-270°-180°) on each bank of a 90° V8 engine causes the blowdown interference effects to vary dramatically between cylinders.

The Ford GT is a high performance sports car designed to compete with the best that the global automotive industry has to offer. A critical enabler for the performance that a vehicle in this class must achieve is the stiffness and response of the frame structure to the numerous load inputs from the suspension, powertrain and occupants. The process of designing the Ford GT spaceframe started with a number of constraints and performance targets derived through vehicle dynamics CAE modeling, crash performance requirements, competitive benchmarking and the requirement to maintain the unique styling of the GT40 concept car. To achieve these goals, an aluminum spaceframe was designed incorporating 35 different extrusion cross-sections, 5 complex castings, 4 smaller node castings and numerous aluminum stampings.