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Aerodynamic had played a primary role in high performance car since the late 1960s, when introduction of the first inverted wings appeared in some formulas. Race car aerodynamic optimisation is one of the most important reason behind the car performance. Moreover, for high performance car using naturally aspired engine, car aerodynamic has a strong influence also on engine performance by its influence on the engine airbox. To improve engine performance, a detailed fluid dynamic analysis of the car/airbox interaction is highly recommended. To design an airbox geometry, a wide range of aspects must be considered because its geometry influences both car chassis design and whole car aerodynamic efficiency. To study the unsteady fluid dynamic phenomena inside an airbox, numerical approach could be considered as the best way to reach a complete integration between chassis, car aerodynamic design, and airbox design.

A realistic modeling of the wall heat transfer is essential for an accurate analysis and simulation of the working cycle of internal combustion engines. Empirical heat transfer formulations still dominate the application in engine process simulations because of their simplicity. However, experiments have shown that existing correlations do not provide satisfactory results for all the possible operation modes of hydrogen internal combustion engines. This paper describes the application of a flow field-based heat transfer model according to Schubert et al. [1]. The models strength is a more realistic description of the required characteristic velocity; considering the influence of the injection on the global turbulence and on the in-cylinder flow field results in a better prediction of the wall heat transfer during the compression stroke and for operations with multiple injections. Further an empirical hypothesis on the turbulence generation during combustion is presented.

In this work, a quasi-dimensional, multi-zone combustion model is analytically presented, for the prediction of performance and nitric oxide (NO) emissions of a homogeneous charge spark ignition (SI) engine, fueled with biogas-H2 blends of variable composition. The combustion model is incorporated into a closed cycle simulation code, which is also fully described. Combustion is modeled on the basis of turbulent entrainment theory and flame stretch concepts. In this context, the entrainment speed, by which unburned gas enters the flame region, is simulated by the turbulent burning velocity of a flamelet model. A flame stretch submodel is also included, in order to assess the flame response on the combined effects of curvature, turbulent strain and nonunity Lewis number mixture. As far as the burned gas is concerned, this is treated using a multi-zone thermodynamic formulation, to account for the spatial distribution of temperature and NO concentration inside the burned volume.

A numerical investigation on a series of Diesel spray experiments in constant-volume vessels is proposed. Non reacting conditions were used to assess the spray models and to determine the grid size required to correctly predict the fuel-air mixture formation process. To this end, not only computed liquid and vapor penetrations were compared with experimental data, but also a detailed comparison between computed and experimental mixture fraction distributions was performed at different distances from the injector. Grid dependency was reduced by introducing an Adaptive Local Mesh Refinement technique (ALMR) with an arbitrary level of refinement. Once the capabilities of the current implemented spray models have been assessed, reacting conditions at different ambient densities and temperatures were considered. A Perfectly Stirred Reactor (PSR) combustion model, based on a direct integration of complex chemistry mechanisms over a homogenous cell, was adopted.

The acoustic impedance of a circular, confined, side branch orifice subjected to grazing flow is studied. Two geometries are tested. In both geometries, the side branch dimension is of the same order as that of the main duct. The system is viewed as an acoustic three-port, whose passive properties are described by a system matrix. The impedance is studied with the acoustic field incident at different ports, which is shown to influence the results significantly. When excited from the leading edge or from the side branch, an interaction of the hydrodynamic and acoustic fields is triggered, while excitation from the trailing edge does not trigger such an interaction. For both the resistance and the reactance (here expressed as an end correction) the results vary in the three possible excitation cases. In the quasi-stationary limit the resistance is given by a loss coefficient times the Mach number, and the end correction collapses to a single value.

The investigation of the flow through the metering section of hydraulic components plays a fundamental role in the design and optimization processes. In this paper the flow through a closed center directional control valve for load -sensing application is studied by means of a multidimensional CFD approach. In the analysis, an open source fluid-dynamics code is used and both cavitation and turbulence are accounted for in the modeling. A cavitation model based on a barotropic equation of state and homogeneous equilibrium assumption, including gas absorption and dissolution in the liquid medium, is adopted and coupled to a two equation turbulence approach. Both direct and inverse flows through the metering section of the control valve are investigated, and the differences in terms of fluid - dynamics behavior are addressed In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated and compared.

Brake judder is about oscillations excited by brake application, which are generated in the contact area between brake pad and brake disc and are transmitted by the elements of the suspension to body and steering system. The driver perceives these perturbations as brake pedal pulsations, steering wheel rotational and body vibrations. The evaluation of a suspension concerning brake judder often takes place for the first time in road tests, since established simulation processes with a high significance concerning ride comfort are missing. At such a late moment necessary modifications in the development process are only hardly possible and very expensive. For avoiding brake judder a systematic development process is needed for brake and suspension. Each one can separately be improved in measurably borders so that their assembly is free of cold brake judder. The present paper shows appropriate test and simulation methods to achieve this.

Scope of the DRESS project is to research, develop and validate a distributed and redundant electrical steering system technology for an aircraft nose landing gear. The new system aims to: • reduce system weight at aircraft level, replacing the current hydraulic actuation system with an electric one. • improve aircraft safety, achieving higher system redundancy levels compared to the current technology capabilities. This paper presents an outline of different activities occurring in the DRESS project and also shows preliminary results of the new system performance.

Patents granted recently to Mr. Rode have changed the industry capability to adjust and verify wheel-end bearings on trucks. Until now it was believed1 that there was nothing available to confirm or verify the most desirable settings of preload on these bearings. The new, breakthrough invention is a tool and spindle-locking nut that permit quick and accurate wheel bearing adjustment by utilizing direct reading force measurement. Bearings can be set to either SAE recommended preloads or specific endplay settings. The author has been working on bearing adjustment methods for industrial applications for over forty years, and considers these inventions to be his most important breakthrough for solving this elusive bearing adjustment problem. Consistent wheel bearing preload adjustment was not possible before, even though it was widely known to achieve the best wheel performance as noted in SAE specification J2535 and re-affirmed in 2006 by the SAE Truck and Bus Wheel Subcommittee.

A heavy truck wind tunnel test program is currently underway at the Langley Full Scale Tunnel (LFST). Seven passive drag reducing device configurations have been evaluated on a heavy truck model with the objective of understanding the practical limits to drag reduction achievable on a modern tractor trailer through add-on devices. The configurations tested include side skirts of varying length, a full gap seal, and tapered rear panels. All configurations were evaluated over a nominal 15 degree yaw sweep to establish wind averaged drag coefficients over a broad speed range using SAE J1252. The tests were conducted by first quantifying the benefit of each individual treatment and finally looking at the combined benefit of an ideal fully treated vehicle. Results show a maximum achievable gain in wind averaged drag coefficient (65 mph) of about 31 percent for the modern conventional-cab tractor-trailer.

The timing and associated levels of braking between initial brake pedal application and actual maximum braking at the wheels for a tractor-semitrailer are important parameters in understanding vehicle performance and response. This paper presents detailed brake timing information obtained from full scale instrumented testing of a tractor-semitrailer under various conditions of load and speed. Brake timing at steer, drive and semitrailer brake positions is analyzed for each of the tested conditions. The study further seeks to compare the full scale test data to predicted response from detailed heavy truck computer vehicle dynamics simulation models available in commercial software packages in order to validate the model's brake timing parameters. The brake timing data was collected during several days of full scale instrumented testing of a tractor-semitrailer performed at the Transportation Research Center, in East Liberty, Ohio.

A series hydraulic hybrid concept (SHHV) has been explored as a potential pathway to an ultra-efficient city vehicle. Intended markets would be congested metropolitan areas, particularly in developing countries. The target fuel economy was ~100 mpg or 2.4 l/100km in city driving. Such an ambitious target requires multiple measures, i.e. low mass, favorable aerodynamics and ultra-efficient powertrain. The series hydraulic hybrid powertrain has been designed and analyzed for the selected light and aerodynamic platform with the expectation that (i) series configuration will maximize opportunities for regeneration and optimization of engine operation, (ii) inherent high power density of hydraulic propulsion and storage components will yield small, low-cost components, and (iii) high efficiency and high power limits for accumulator charging/discharging will enable very effective regeneration.

Today, high performance race car efficiency is based on a very fine equilibrium between aerodynamic efficiency, engine performance, and chassis behaviour. In particular, from the engine point of view, one way to increase the performance is to increase its volumetric efficiency. The aim of this paper is to present the application of the Large Eddy Simulation (LES) approach for the fluid dynamic analysis of a high performance race car airbox geometry. For a naturally aspired engine, the fluid dynamic optimisation of the airbox geometry means to optimise the energy conversion (from dynamic to static pressure) inside the airbox itself, therefore to increase the flow energy on the engine trumpet sections. The LES approach seems to be the best candidate to investigate such a flow since flow unsteadiness are expected to affect airbox efficiency in terms of pressure recovery. The airbox simulations were performed by using the commercial CFD code Fluent v6.3.

Japanese Experiment Module (JEM) called KIBO is the first manned space structure in Japan. Among several high technologies of JEM development, achievement of the air ventilation (AV) under the micro gravity was challenging because the requirements were very difficult to meet. The verification test in the module level under the operation of the flight hardware had a serious problem by the natural convection owing to the heat generation by the flight hardware. The analysis had problems how to verify its own validity because the turbulent flow around diffuser exits in addition to the laminar flowfield where the velocity is extremely small. This paper describes the solution of these problems in the analytical and testing verification points of view. As a result, we found our analysis applied to the AV performance could provide the complicated flowfield in low velocity with the effects of turbulent flow as well as natural convection.

The paper presents linear and non-linear driveline models for Heavy Goods Vehicles (HGVs) in order to evaluate the main parameters for optimal tuning, when considering the drivability. The implemented models consider the linear and non-linear driveline dynamics, including the effect of the engine inertia, the clutch damper, the driveshaft, the half-shafts and the tires. Sensitivity analyses are carried out for each driveline component during tip-in maneuvers. The paper also analyses the overall frequency response using Bode diagrams and natural frequencies. It is demonstrated that the most basic model capable of taking into account the first order dynamics of the driveline must consider the moments of inertia of the engine, the transmission and the wheels, the stiffness and the damping properties of the clutch damper, driveshaft and half-shafts, and the tires (which link the wheel to the equivalent inertia of the vehicle).

Scuffing is a common source of failure for many mechanical components in automobiles. 8625 alloy steel is commonly used in camshafts, gears, piston pins, shafts, and splines. The purpose of the research is to study the scuffing resistance of non-treated, carburized, nitrocarburized, and carbonitrided 8625 alloy steels. The scuffing resistance of the 8625 alloy steels was determined through pin-on-disk tests. The hardness and microstructure of the disks were analyzed using electron microscopy to determine wear mechanisms for each surface treated steel. The wear mechanisms were then related to the scuff resistance of the various materials.

Recently Michelin has been developing a new airless, integrated tire and wheel combination called the Tweel® tire. The Tweel tire aims at performance levels beyond those possible with conventional pneumatic technology because of its shear band design, added suspension, and potentially decreased rolling resistance. In this paper, we will focus on the environmental impact of the Tweel tire during its life-cycle from manufacturing, through use and disposal. Since the Tweel tire is currently still in the research phase and is not manufactured and used on a large scale, there are uncertainties with respect to end-of-life scenarios and rolling resistance estimates that will affect the LCA. Nevertheless, some preliminary conclusions of the Tweel tire's environmental performance in comparison to a conventional radial tire can be drawn.

Al383/SiO₂ metal matrix composites (MMC) were designed to increase the wear properties of the Al alloy. However, the soft Al matrix was subject to large plastic deformation under high normal load during lubricated sliding wear tests, causing detachment of the reinforced particles. To further increase the wear resistance of the MMC, in this research, Plasma Electrolytic Oxidation (PEO) process was used to form oxide coatings on the MMC. The hard and wear-resistant oxide coatings protected the metal matrix during the wear tests, reducing the wear rate of MMC. The effect of both oxide coating thickness and volume content of SiO₂ particles on the wear behavior of MMC was investigated. It was found that with a proper combination of the volume content of SiO₂ and coating thickness, the MMC exhibited high wear resistance and low friction coefficient.

This paper describes a driving controller to improve vehicle lateral stability and maneuverability for a six wheel driving / six wheel steering (6WD/6WS) vehicle. The driving controller consists of upper and lower level controller. The upper level controller based on sliding control theory determines front, middle steering angle, additional net yaw moment and longitudinal net force according to reference velocity and steering of a manual driving, remote control and autonomous controller. The lower level controller takes desired longitudinal net force, yaw moment and tire force information as an input and determines additional front steering angle and distributed longitudinal tire force on each wheel. This controller is based on optimal distribution control and has considered the friction circle related to vertical tire force and friction coefficient acting on the road and tire.

The adhesion control is the basic technology of active safety for the four-wheel driven EV. In this paper, a novel adhesion control method based on fuzzy logic control is proposed. The control system can maximize the adhesion force without road condition information and vehicle speed signal. Also, the regulation torque to prevent wheel slip is smooth and the vehicle driving comfort is greatly improved. For implementation, only the rotating speed of the driving wheel and the motor driving torque signals are needed, while the derived information of the wheel acceleration and the skid status are used. The simulation and road test results have shown that the adhesion control method is effective for preventing slip and lock on the slippery road condition.