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Vehicle designers make use of vehicle performance programs such as RAPTOR™ to predict the performance of concept vehicles over ranges of industry standard drive cycles. However, the accuracy of such predictions may be greatly influenced by factors requiring more specialist simulation capabilities. For example, fuel economy prediction will be heavily influenced by the performance of the engine cooling system and its impact on the vehicle's aerodynamic drag, and the load from the air-conditioning system. To improve the predictions, specialist simulation capabilities need to be applied to these aspects, and brought together with the vehicle performance calculations through co-simulation. This paper describes the approach used to enable this cosimulation and the benefits achieved by the vehicle designer.

This paper describes the development of a generic test cell software designed to overcome many vehicle-component testing difficulties by introducing modern, real-time control and simulation capabilities directly to laboratory test environments. Successfully demonstrated in a transmission test cell system, this software eliminated the need for internal combustion engines (ICE) and test-track vehicles. It incorporated the control of an advanced AC induction motor that electrically simulated the ICE and a DC dynamometer that electrically replicated vehicle loads. Engine behaviors controlled by the software included not only the average crankshaft torque production but also engine inertia and firing pulses, particularly during shifts. Vehicle loads included rolling resistance, aerodynamic drag, grade, and more importantly, vehicle inertia corresponding to sport utility, light truck, or passenger cars.

A computer-controlled body panel testing machine has been used to quantify stiffness and dent resistance of body panels at Chrysler. The influence of yield strength and local reinforcement on the mechanical behavior of automotive door panels has been investigated. Medium strength steels in the range of 210 -240 MPa yield strength have produced significant improvements in dent resistance over a 160 MPa yield strength steel. Considerable improvements in dent resistance can also be attributed to the use of local, adhesively attached, glass fiber reinforcement patches. The effects of boundary conditions and panel shape on stiffness and dent resistance are illustrated in this application.

The engine intake process governs many aspects of the flow within the cylinder. The inlet valve is the minimum area, so gas velocities at the valve are the highest velocities seen. Geometric configuration of the inlet ports and valves, and the opening schedule create organized large scale motions in the cylinder known as swirl and tumble. Good charge motion within the cylinder will produce high turbulence levels at the end of the compression stroke. As the turbulence resulting from the conversion energy of the inlet jet decays fast, the strategy is to encapsulate some of the inlet jet in the organized motions. In this work the baseline port of a 2.0 L gasoline engine was modified by inserting a tumble plate. The work was done in support of an experimental study for which a new single-cylinder research engine was set up to allow combustion system parameters to be varied in steps over an extensive range. Tumble flow was one such parameter.

Tests were conducted on a variety of commercially available spark plugs to determine the influence of igniter design on initial kernel formation and overall performance. Flame kernel formation was investigated using high-speed schlieren visualization. The flame growth rate was quantified using the area of the burned gas region. The results showed that kernel growth rate was heavily influenced by electrode geometry and configuration. The igniters were also tested in a bomb calorimeter to determine the levels of supplied and delivered energy. The typical ratio of supplied to delivered energy was 20% and igniters with a higher internal resistance delivered more energy and had faster kernel formation rates. The exception was plugs with large amounts of conductive mass near the electrodes, which had very slow kernel formation rates despite relatively high delivered energy levels.

The composition of natural gas delivered through the pipeline varies with time and location around the USA. These variations are known to affect engine performance and emissions through changes in fuel metering characteristics and knock resistance of the fuel. High output, low emissions natural gas engines are being developed that take advantage of the high knock resistance of natural gas. These optimized engines are operated close to knock-limited power where changes in fuel knock resistance can cause operational problems. Octane tests were conducted on natural gas blend fuels using a CFR octane rating engine. Two relationships between motor octane number and fuel composition were established. A correlation for motor octane number versus the reactive hydrogen-carbon ratio was developed, and octane weighting factors, which used the molar composition of the fuel to predict motor octane number, were also found.

The optical spark plug probe and ionization head gasket probe developed at Sandia Laboratories were applied to one cylinder of a production multicylinder automotive gasoline engine. The purpose of this application is to eventually study combustion phenomena leading to high emissions under cold start and cold idle conditions. As a first step in studying cold start combustion and emissions issues, diagnostic instrumentation was simultaneously applied to a production engine under steady state idle, road load and an intermediate load-speed condition. The preliminary application of such instrumentation is the subject of the present paper. The spark plug probe was redesigned for ease of use in production engines and to provide a more robust design. The two probes were geometrically oriented to obtain radial line-up between the optical windows and ionization probes. Data were taken simultaneously with both probes at the three load-speed conditions mentioned above.

Resistance to dents and dings, caused by plant handling and in-service use, is generally recognized as an important performance requirement for automotive outer body panels. This paper examines the dent resistance improvements that can be achieved by maximizing surface stretch, through adjustments to the press settings, and substitution of a higher strength steel grade. Initially, the stamping process was optimized using the steel supplied for production: a Ti/Nb-stabilized, ultra low carbon (ULC) grade. The stamping process was subsequently optimized with a Nb-stabilized, rephosphorized ULC steel, at various thicknesses. The formed panels were evaluated for percent surface stretch, percent thinning, in-panel yield strength after forming, and dent performance. The results showed that dent resistance can be significantly improved, even at a reduced steel thickness, thus demonstrating a potential for weight savings.

Fastener failure due to hydrogen embrittlement is of significant concern in the automotive industry. These types of failures occur unexpectedly. They may be very costly to the automotive company and fastener supplier, not only monetarily, but also in terms of customer satisfaction and safety. This paper is an overview of a program which one automotive company initiated to minimize hydrogen embrittlement in fasteners. The objectives of the program were two-fold. One was to obtain a better understanding of the hydrogen embrittlement phenomena as it relates to automotive fastener materials and processes. The second and most important objective, was to eliminate hydrogen embrittlement failures in vehicles. Early program efforts concentrated on a review of fastener applications and corrosion protection systems to optimize coated fasteners for hydrogen embrittlement resistance.

Emission performance of a late model vehicle equipped with an electrically-heated catalytic converter (EHC) system was evaluated after extended vehicle soak periods that ranged from 30 to 180 minutes. As soak periods lengthened, NMHC and CO emissions measured in hot transient driving cycles increased by 125 percent and 345 percent, respectively. These tests were baseline operations which had no resistance heating or secondary air injection to the converter system. Sources of increased NMHC and CO emissions as a function of vehicle soak time were both the converter system cool-down characteristics and engine restart calibration strategy. For soak periods of 30 and 60 minutes, EHC resistance heating without secondary air injection resulted in large improvements in NMHC and CO emission performance (i.e., 74 percent and 54 percent lower NMHC emissions versus no heat, no air operation after a 30- and 60-minute period, respectively).

A better understanding of turbulent kinetic energy is important for improvement of fuel-air mixing, which can lead to lower emissions and reduced fuel consumption. An in-cylinder flow study was conducted using 1548 Laser Doppler Velocimetry (LDV) measurements inside one cylinder of a 3.5L four-valve engine. The measurement method, which simultaneously collects three-dimensional velocity data through a quartz cylinder, allowed a volumetric evaluation of turbulent kinetic energy (TKE) inside an automotive engine. The results were animated on a UNIX workstation, using a 3D wireframe model. The data visualization software allowed the computation of TKE isosurfaces, and identified regions of higher turbulence within the cylinder. The mean velocity fields created complex flow patterns with symmetries about the center plane between the two intake valves. High levels of TKE were found in regions of high shear flow, attributed to the collisions of intake flows.

In recent years, strict weight reduction targets have pushed auto manufacturers to use lighter gauge sheet steels in all areas of the vehicle including exterior body panels. As sheet metal thicknesses are reduced, dentability of body panels becomes of increasing concern. Thus, the goal becomes one of reducing sheet metal thickness while maintaining acceptable dent resistance. Most prior work in this area has focused on quasi-static loading conditions. In this study, both quasi-static and dynamic dent tests are evaluated. Fully assembled doors made from mild, medium strength bake hardenable and non-bake hardenable steels are examined. The quasi-static dent test is run at a test speed of 0.1 m/minute while the dynamic dent test is run at a test speed of 26.8 m/minute. Dynamic dent testing is of interest because it more closely approximates real life denting conditions such as in-plant handling and transit damage, and parking lot damage from car door and shopping cart impact.

The purpose of this paper is to present numerical solution for three-dimensional flow about rotating short cylinders using the computer program AIRFLO3D. The flow Reynolds number was kept at 106 for all computations. The drag forces on the cylinder were obtained for different rotational speeds. Predictions were obtained for both an isolated cylinder and a cylinder on a moving ground. The standard k-ε model was employed to model the turbulence. Computed drag coefficients agreed well with the previous experimental data up to a spin ratio (=rω/V) of 1.5.

The aerodynamic features of the race version of the Charger Daytona, an aerodynamically modified 1970 Charger, are discussed. Effects of major specific modifications are evaluated individually and as a total package. Wind tunnel techniques and philosophy employed in the Daytona Development Program are also discussed.

One solution to the problem of spiraling automotive weights is the substitution of thinner high strength steels or thicker aluminum alloy outer body panels. In doing so the dent resistance of these panels must not be sacrificed. This study investigates the dent resistance of doubly curved rectangular panels in various steels and aluminum alloys. Dent depth on the order of magnitude of the panel thickness was studied. An empirical equation is developed that relates dent resistance to the yield strengths, metal thickness, and panel geometry.

AS a basis for the analyses of this symposium, a hypothetical car has been used to evaluate the engine power distribution in performance. Effects of fuel,-engine accessories, and certain car accessories are evaluated. The role of the transmission in making engine power useful at normal car speeds is also discussed. Variables encountered in wind and rolling resistance determinations are reevaluated by improved test techniques. Net horsepower of the car in terms of acceleration, passing ability and grade capability are also summarized.

THIS paper outlines tests made to verify the SAE recommended practice for estimating truck ability performance described in TR-82. The author has collected data on four vehicles and compares it with the results computed in TR-82 and with a Method X. The data includes information on air and rolling resistance, effect of wind velocity, chassis friction power, grade ability, and the like. The author concludes that the SAE method of TR-82 is at the present time the most reliable method for computing truck ability.

The heater air flow rate is a function not only of the heater itself but also of the size and location of the heater system air inlets, the car body air outlets, and the body surface pressure at these inlets and outlets. Favorable pressure conditions generally exist at the typical top cowl heater air inlet; however, the aerodynamics of each particular vehicle should be studied to confirm the existence of these conditions. Little consideration has been given to body air outlet pressure conditions since body leakage paths have generally served as adequate air outlets; but, as body leakage is reduced, specific air outlets must be considered and a knowledge of aerodynamics is essential to the achieving of appropriately sized and appropriately located air outlets.

Small engines may require soundproofing to eliminate one or more of the following effects: hearing loss, speech interference, community annoyance, detectability, and psychological disorientation. Detectability criteria are frequently associated with military applications and may require the use of a soundproof enclosure in addition to other engine treatments. Acoustical noise sources are conveniently classed as either aerodynamic or mechanical. Aerodynamic sources are predominant on small engines. Treatment of exhaust noise by individual components, e.g., muffler, is inadequate; a system approach, through the use of an electro-acoustic analog computer, has proved to be a much more satisfactory procedure.

Since 1968, vehicle weight increases and emissions controls have reduced fuel economy substantially. Additional losses in economy and acceleration will be experienced through 1976. Recommendations are made to lessen the impact of the predicted losses. Factors influencing fuel economy and acceleration are examined for an intermediate car. Changes in engine efficiency and displacement, compression ratio, torque converter, transmission, axle ratio, aerodynamic drag, tires, accessories, vehicle weight, and emissions controls are examined. When practical, the effects of 10% changes are analyzed. Comparisons are also made with a subcompact and a luxury vehicle.