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The current ability of the Virtual Aerodynamic/ Aeroacoustic Wind Tunnel to predict interior vehicle sound pressure levels is demonstrated using an automobile model which has variable windshield angles. This prediction method uses time-averaged flow solutions from a lattice gas CFD code coupled with wave number-frequency spectra for the various flow regimes to calculate the side window vibration from which the sound pressure level spectrum at the driver's ear is determined. These predictions are compared to experimental wind tunnel data. The results demonstrate the ability of this methodology to correctly predict wind noise spectral trends as well as the overall loudness at the driver's ear. A more sophisticated simulation method employing the same lattice gas code is investigated for prediction of the time-accurate flow field necessary to compute the actual side glass pressure spectra.

Acid rain in the U.S. is becoming a major environmental issue. This paper reviews the known information regarding pollution sources, impact on the environment and the role of the automobile in acid rain. Although natural sources of sulfur and nitrogen pollutants are equal to or greater than man-made sources on a global scale, many scientists believe man's activities are the major cause of high levels of acidity. Attempts to relate specific sources of SO2 to specific acid rain events in the northeastern U. S. have been unsuccessful. The roles of tall stacks, long range transport and dry vs. wet deposition are incompletely understood. Temporal and geographic trends in acidity are not well defined except for increased acidity in the southeast. About 30% of the acidity in rain in the northeast is due to HNO3. In the process of utilizing nitrates as a nutrient, plants partly neutralize the affect of HNO3 in the rain.

A laboratory wear test is used to evaluate the wear protection properties of new and used engine oils formulated for FFV service. Laboratory-blended mixtures of these oils with methanol and water have also been tested. The test consists of a steel ball rotating against three polished cast iron discs. Oil samples are obtained at periodic intervals from a fleet of 3.0L Taurus vehicles operating under controlled go-stop conditions. To account for the effects of fuel dilution, some oils are tested before and after a stripping procedure to eliminate gasoline, methanol and other volatile components. In addition to TAN and TBN measurements, a capillary electrophoresis technique is used to evaluate the formate content in the oils. The results suggest that wear properties of used FFV lubricants change significantly with their degree of usage.

A piezoelectrically driven vibrating cantilever blade is damped by a number of mechanisms including viscous damping in a still fluid and aerodynamic damping in a flow. By measuring the damping of devices operating at resonance in the 1 to 5 kHz region, one can measure such properties as mass flow, absolute pressure or the product of molecualar mass and viscosity. In the case of the mass flow measurement, the device offers a mechanical alternative to hotwire and hot film devices for the automotive application.

This paper explores the extent to which standard dilution tunnel measurements of motor vehicle exhaust particulate matter modify particle number and size. Steady state size distributions made directly at the tailpipe, using an ejector pump, are compared to dilution tunnel measurements for three configurations of transfer hose used to transport exhaust from the vehicle tailpipe to the dilution tunnel. For gasoline vehicles run at a steady 50 - 70 mph, ejector pump and dilution tunnel measurements give consistent results of particle size and number when using an uninsulated stainless steel transfer hose. Both methods show particles in the 10 - 100 nm range at tailpipe concentrations of the order of 104 particles/cm3.

Due to several indeterminate factors, the assessment of the durability performance of a vehicle body is traditionally accomplished using test methods. An analytical fatigue life prediction method (four-step durability process) that relies mainly on numerical techniques is described in this paper. The four steps comprising this process include the identification of high stress regions, recognizing the critical load types, determining the critical road events and calculation of fatigue life. In addition to utilizing a general purpose finite element analysis software for the application of the Inertia Relief technique and a previously developed fatigue analysis program, two customized programs have been developed to streamline the process into an integrated, user-friendly tool. The process is demonstrated using a full body, finite element model.

The purpose of this study was to determine the optimal location of the shoulder belts for a suspender style four-point safety belt system. This optimal location must satisfy two conditions. First, the shoulder belts must properly fit over the occupant’s shoulders for safety performance. Second, the shoulder belts location on the occupant’s body must be acceptable to the occupant. To determine the optimal acceptable location of the shoulder belts, forty-four subjects were recruited by height and tested in a reconfigurable test seat. The results showed that avoiding an interaction between the shoulder belts and the occupant’s neck improved the acceptability of the system. Variables that affected this interaction included the horizontal and vertical position of the shoulder belts and the occupant’s weight, clothing, and gender.

Locations of key body segments of Hybrid III dummies used in FMVSS 208 compliance tests and NCAP tests were measured and subjected to statistical analysis. Mean clearance dimensions and their standard deviations for selected body segments of driver and passenger occupants with respect to selected vehicle surfaces were determined for several classes of vehicles. These occupant locations were then investigated for correlation with impact responses measured in crash tests and by using a three dimensional human-dummy mathematical model in comparable settings. Based on these data, the importance of some of the clearance dimensions between the dummy and the vehicle surfaces was determined. The study also compares observed Hybrid III dummy positions within selected vehicles with real world occupant positions reported in published literature.

As vehicle tailpipe emission levels decrease with improvements in emission control technology and reformulation of gasolines, exhaust hydrocarbon levels begin to approach the levels in ambient air. Hydrocarbon speciation at these low levels requires high sensitivity capillary gas chromatography methods. In this study, a mixture of “synthetic” exhaust was prepared at two concentration levels (approximately 5 ppm C and 10 ppm C), and was analyzed by the widely-used Auto/Oil Air Quality Improvement Research Program (AQIRP) Phase II (gas chromatography) speciation method with a sensitivity of 0.005 ppm C for individual species. The mixture at each concentration level, along with a sample of ambient air, was analyzed a total of 20 times on 10 separate days over a 2½ week period. Concentrations of total hydrocarbons (HCs) and individual species (using the AQIRP library) were measured; averages and standard deviations were calculated.

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.

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 worldwide automotive industry is currently preparing for a market introduction of hydrogen-fueled powertrains. These powertrains in fuel cell electric vehicles (FCEVs) offer many advantages: high efficiency, zero tailpipe emissions, reduced greenhouse gas footprint, and use of domestic and renewable energy sources. To realize these benefits, hydrogen vehicles must be competitive with conventional vehicles with regards to fueling time and vehicle range. A key to maximizing the vehicle's driving range is to ensure that the fueling process achieves a complete fill to the rated Compressed Hydrogen Storage System (CHSS) capacity. An optimal process will safely transfer the maximum amount of hydrogen to the vehicle in the shortest amount of time, while staying within the prescribed pressure, temperature, and density limits. The SAE J2601 light duty vehicle fueling standard has been developed to meet these performance objectives under all practical conditions.

As part of a general EGR system model, an adiabatic thermodynamic vacuum EGR valve actuator model was developed and validated. The long term goal of the work is improved system operation by correctly specifying and allocating EGR system component requirements.

The internally programmed two-injection method for determining the dissolved air correction in the CCA-VP laboratory vapor pressure instrument (Grabner Instruments), while adequate for pure, single component liquids, can be in error for full boiling range automotive fuels. For these fuels, errors of up to 10 kPa (1.5 psi) in vapor pressure at 38°C (100°F) can occur due to the increase in vapor pressure between the first and second injection caused by decreasing vapor liquid ratio (V/L); this increase is interpreted by the instrument as additional dissolved air and results in overcorrection for this effect. A method is demonstrated for removing the V/L effect using two TV/L values for the subject fuel, either calculated or measured independently. The true air correction determined in this way is similar to values obtained for single component fuels and to values calculated directly from air solubility data.

The increased focus on occupant protection by automobile manufacturers combined with incessant consumer demand for safety features such as dual airbags has posed design engineers with major challenges in the field of Instrument Panel (IP) design. Typically, airbags are designed to deploy when the speed of the automobile is above 13 mph in a frontal impact. The airbag door should meet head impact requirements for unbelted occupants involved in low speed impacts (<15mph) when airbags are not deployed. This paper describes how computer aided engineering (CAE) simulation techniques were used in improving the design of the passenger airbag door of a full size van for head impact performance. Fewer tests were conducted primarily for validation, which resulted in significantly less prototypes, costs and time.

A novel non-phosphorus antiwear additive, NP-1, was evaluated as a partial substitute for zinc dialkyldithiophosphate (ZDTP). ZDTP, an antiwear/antioxidant engine oil additive may under certain conditions cause three way catalyst (TWC) deactivation due to formation of an amorphous zinc pyrophosphate, Zn2P2O7, glaze. Antiwear and antioxidant properties of NP-1 alone and in combination with ZDTP were compared with ZDTP only containing formulations. The effects of NP-1 on TWC activity during pulsator modulation and steady-state conditions showed that the TWC maintained good overall activity during 24,000 simulated miles.

During frontal and rear end type collisions, very large forces will be imparted to the passenger compartment by the collapse of either front or rear structures. NCAP tests conducted by NHTSA involve, among other things, a door openability test after barrier impact. This means that the plastic/irreversible deformations of door openings should be kept to a minimum. Thus, the structural members constituting the door opening must operate during frontal and rear impact near the elastic limit of the material. Increasing the size of a structural member, provided the packaging considerations permit it, may prove to be counter productive, since it may lead to premature local buckling and possible collapse of the member. With the current trend towards lighter vehicles, recourse to heavier gages is also counterproductive and therefore a determination of an optimum compartment structure may require a number of design iterations. In this article, FEA is used to simulate front side door behavior.

The feasibility of using experimentally determined flow fields at intake valve closing, IVC, as initial conditions for computing the in-cylinder flow dynamics during the compression stroke is demonstrated by means of a computer simulation of the overall approach. A commercial CFD code, STAR-CD, was used for this purpose. The study involved two steps. First, in order to establish a basis for comparison, the in-cylinder flow field throughout the intake and compression strokes, from intake valve opening, IVO, to top dead center, TDC, was computed for a simple engine geometry. Second, experimental initial conditions were simulated by randomly selecting and perturbing a set of velocity vectors from the computed flow field at IVC.

Automotive product development requires higher degree of quality upfront engineering, faster CAE turn-around, and integration with other functional requirements. Prediction of potential durability concerns using analytical methods for sheet metal structures subjected to road loads and other customer uses has become very important. A process has been developed to provide design direction based upon peak loads, simultaneous peak loads, and vehicle program analytical or measured loads. It identifies critical loads at each input location and load sets for multiple input locations, filters load time histories, selects critical areas and analyzes for fatigue life. Several case studies have been completed. The results show that the variations are consistent with the accuracies in finite element analysis, road load data acquisition, and fatigue calculation methods.

This paper compares the emissions performance of four ultra thin wall ceramic substrates with standard wall thickness product on a chassis dynamometer for two different substrate volumes. This comparison helps establish performance trends and provides useful information for selection of substrates in designing catalytic converter systems. This experimental study tests and compares four ultra thin wall products (400/4, 600/3, 600/4, and 900/2) with a standard wall product (400/6.5) at two different substrate volumes. Engine bench aging is used to simulate typical aged conditions. Temperature data as well as second by second and bag emissions data for hydrocarbons, carbon monoxide and oxides of nitrogen were used to evaluate the relative performances of the substrates. The US FTP and US06 driving cycles were used as protocols for the comparison. Results suggest that lower bulk density and higher geometric surface area interact to lead to lower emissions.