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The effect of rear splitter plates and base cavities on the near wake behind a ground vehicle body above a moving ground plane were studied. Static pressure taps on the base of the body were used to measure both the mean and fluctuating pressures acting on the model base. Hot wire anemometry and flow visualization were used to study the effect of splitter plates and cavities on the near wake velocity field. The effects of varying ground clearance and of the moving ground on the base pressure were also studied. It was determined that some splitter plate configurations affect the base pressure distribution by forming a low pressure vortex on one side of the plate with high pressure fluctuations and altering the flow on the opposite side of the plate to raise the mean pressure. The suction region could be eliminated by moving the splitter plate to the model edge to form a side of a cavity. A full four sided cavity was able to increase the overall base pressure by 11% on the model.

The transmission of aerodynamically-generated noise through panels in automobiles has become of more pressing interest in recent years. As automobile engines, transmissions, and tires have become quieter, wind noise has become more noticeable, particularly at higher speeds. Hence, an automobile manufacturer would like to know how to design the automobile to minimize the wind noise levels heard by the passengers. In this investigation, both experimental and analytical methods were applied to the problem. A simplified model of an automobile side window was subjected to wind tunnel tests. The effects of window thickness and edge conditions on the transmitted wind noise level were investigated. An attempt was made to analytically predict the transmitted noise level by using a simple Statistical Energy Analysis (SEA) model, which used an empirical expression for the fluctuating wall pressure on the window of an automobile.

A numerical analysis method is developed for predicting the pressure fluctuations on the front side window surface, aiming at the elucidation of the external aerodynamic flow structure about the front pillar of a road vehicle. The simulated results are assessed by comparison with the acoustic theory and reveal fairly well the dependence of the predicted surface pressure fluctuations upon the vehicle cruising speed with the sixth power law. The features of three dimensional vortical flow are clarified from the analysis of the simulated results, indicating the strong relationship between the vortical formation and the external pressure fluctuations on the front side window surface. The external pressure fluctuations seem to be strongly related to the vortex breakdown during its interaction with the front side window and the roof-side window junction.

A two-channel LDV system is used to obtain accurate airflow measurements around scale models of passenger cars in wind tunnel tests at the Nissan Research Center. A 2-watt argon-ion laser is employed as the light source. The main optical unit and probe head are connected by optical fibers. The probe head consists of a compact LDV probe with a beam expander and focusing lens with a long focal length can be easily traversed. A new type of signal processor, performing a digital autocorrelation function, is employed to process the Doppler signals. Mean airflow velocities and turbulence intensities are calculated by a micro computer to evaluate the flow fields. The results of preliminary experiments conducted with this system indicate that the system is not only capable of measuring the mean velocity components, including reverse flow, it can also provide accurate estimation of turbulence components.

Modern vehicles require a low aerodynamic drag to minimize fuel consumption. A not negligible share of the overall CD-value of a vehicle is produced by the engine compartment air flow. Therefore this share has also to be optimized. Furthermore, customer wishes for higher powered engines as well as for more safety and comfort result in more tightly packed engine compartments. Even the reduction of pass-by-noise required by legal reasons is often achieved with the help of underbody covers which in turn affect the engine compartment flow. All these items may lead to rising underhood temperatures. To reduce the development time of new vehicles, numerical simulations of engine compartment air flow are more and more used to predict high temperature fields and to show ways to develop suitable remedies in the concept phase of the vehicle development. The experimental basis for such codes is provided by aerodynamic investigations in a wind tunnel.

A method of retro-fitting automotive air-conditioning systems from CFC12 to HFC134a has been developed. This method only requires the use of conventional refrigerant recovery and recycle machines and offers a cost effective method of retrofitting a range of automotive air-conditioning systems to HFC 134a.

High performance engines required in contemporary vehicles are causing underhood components to operate under hostile temperature environments. Aerodynamic styling and the addition of new components to the engine compartment further add to the problem by decreasing the volume of underhood cooling air flow. The addition of engine compartment coverings required to meet environmental noise reduction standards further restrict and debilitate air flow cooling. The above conditions demand that the analysis of air flow patterns and heat transfer phenomena under the hood be an essential part of early systems design of new engines, engine compartment components, and underhood component packaging. A numerical approach to calculate cooling air flow velocity and temperature distribution of the air and engine compartment components is utilized. Air flow is calculated using a finite volume Computational Fluid Dynamics code on a 220,000 cell representation of the flow domain.

The flow around a simplified vehicle-like body was computed. The aerodynamic characteristics of this body depended on the afterbody geometry, especially the rear slant angle. In order to examine reliability of computation, the computations were performed for various rear slant angles. Regarding the computational method, two kinds of methods were applied: a Navier-Stokes solver that employs a k- ε turbulence model and a quasi-direct simulation with a third-order upwind difference scheme. Comparing the results with a wind tunnel test data of the flow fields and aerodynamic forces, it was found that, the k- ε model had potential for prediction of flow field and the quasi-direct simulation for prediction of aerodynamic forces.

A numerical study of an automotive windshield ice-clearing was successfully accomplished. The windshield clearing process is a 3D transient, multi-medium, multi-phase heat exchange phenomenon in connection with the air flow distribution in the passenger compartment. The transient windshield clearing analysis employed conjugate heat transfer and enthalpy methods to simulate the ice-melting pattern and the melting duration. This study is a joint project between Chrysler Corporation and CFD Research Corporation. A Chrysler prototype windshield and test vehicle were utilized. The meshing was done using ICEM/CFD package by Control Data Corporation (CDC). A seamless data transfer was achieved by developing an interface between ICEM/CFD and CFD-ACE. The analysis of air flow, conjugate heat transfer, and weather clearing was performed using the multi-domain CFD-ACE code developed by CFD Research Corporation (CFDRC).

This paper describes a flexible-film bladder, mode door. An air line is attached directly to the flexible valve through the mode housing or air duct for vacuum or positive pressure actuation. This technology addresses the need for more compact designs, part reduction and weight savings. It is designed to replace current mode valve doors, actuators and associated brackets. The propounded benefits of this design are outlined along with design considerations and part/system validation testing.

Predominant failure modes in the forming of sheet metal parts are wrinkling and tearing. Wrinkling may occur at the flange as well as in other areas of the drawn part and is generated by excessive compressive stresses that cause the sheet to buckle locally. Fracture occurs in a drawn material which is under excessive tensile stresses. For a given part and blank geometries, the major factors affecting the occurrence of defects in sheet metal parts are the blank holder force (BHF) and the blank holder pressure (BHP). These variables can be controlled to delay or completely eliminate wrinkling and fracture. Modern mechanical presses are equipped with hydraulic cushions and various advanced multi-point pressure control systems. Thus, the BHP can be adjusted over the periphery of the blank holder as a function of location and time (or press stroke).

A description is made of a modern tool, the Universal Climate Simulator, which is very useful both for the development of new strategies and for the testing of Electronic Control Units for passenger vehicles climate control. This paper shows how it is possible to study the control strategies with a real time model of the internal climate of a vehicle, though a precise simulation of the internal climate of an automobile is not a simple task. The main problem is the huge number of phenomena to be taken into account with a necessarily simple model, while, on the other hand, it is important to study the efficacy of the control in any situation, under the influence of any possible perturbation. The model structure proposed is a set of nonlinear differential equations, which are deduced directly from a physical model. As a consequence, all the parameters to be identified in this model have their physical meaning.

A highly accurate fuel sensing system has been developed which provides a digital indication of the remaining fuel on a l/P cluster. This system uses capacitance type sensors placed in the fuel tank to detect fuel level changes. This system uses three capacitance type sensors which enables it to determine highly accurate fuel level even in sloped surfaces. This fuel level sensor has been in production since 1991 and today is used on the TOYOTA SOARER in Japan.

We developed amorphous alloy thin films having TCR(temperature coefficient of resistivity) less than ±5 ppm/°C for strain gauge applications. Thin film strain gauges are directly formed on metal substrates insulated with SiO2. These gauges have excellent aging stability at high temperature. The resistivity shows a drift in ▵R/R less than ±0.03% at 120°C in 1000 hours. We developed a pressure sensor and an acceleration sensor with high accuracy and reliability, employing these gauges.

This paper highlights recent developments in thermoplastic materials, mold design and molding techniques for the production of encapsulated automotive solenoids and sensors that can well withstand the thermal and chemical conditions prevailing in the automotive operating environment.

In conventional sensor systems, mechanical and electronic components are generally operating at separated locations. Smart sensors integrate mechanical and electronic elements to a single system, thus offering new facilities for a common error compensation. In this concept, a unit-specific temperature dependence and a non-linear characteristic curve of the mechanical sensor element can be tolerated, thus saving a lot of costs in the manufacturing process of the mechanical components. The behaviour of the mechanical sensor element is described by a two-dimensional sensor correction function: Given the output of the mechanical sensor element and a measured value for the temperature, the true measurement value can be calculated by an error correction unit. In this paper, different error correction methods are examined and evaluated which can be used for a wide range of sensor types. They are applied to the example of a short-circuit ring displacement sensor.

The role of sensors and sensing technologies for the next generation vehicle systems are discussed. The control systems for engines and power-train are expected to realize high efficiency with low pollution and comfort drivability. Vehicular safety and chassis control systems are expected to avoid many kinds of traffic accidents caused by the human errors of drivers. Vehicular information systems will help the drivers to get the information to manage their vehicles economically and efficiency. In every system mentioned above, sensors and sensing technologies are playing an increasingly important role. This paper introduces and discusses essential technologies for sensors and sensing which can be expected to bring the solutions to the future automotive systems.

Results of laboratory studies of the static characteristics of several different commercially available heated exhaust gas oxygen sensors are described. In these studies, the emf of the sensors was measured as a function of temperature and of the composition of calibrated gas mixtures. Several different binary gas mixtures (H2/N2, CO/N2, C3H6/N2, C3H8/N2, and CH4/N2) were used together with a variable amount of O2. In addition to laboratory studies, the same sensors were also studied in the exhaust gas of an engine. Whereas at high temperatures thermodynamic equilibrium appears to prevail, clear departures from thermodynamic equilibrium are observed at some lower temperatures (the value of which depends on the specific sensor and the specific gas mixture used). This behavior is manifested by shifts of the emf step away from stoichiometry, broadening of the step, abnormally high emf values in excess oxygen mixtures, and abnormally low emf values in reducing gas mixtures.

A Methanol Concentration Smart Sensor has been developed to support the demand for alternately fueled vehicles operating on blends of methanol and gasoline in any mixture up to 85% methanol. The sensor measures concentration by exploiting the difference in dielectric properties between methanol and gasoline. The measurement is made based on the distributed capacitance of a coil of wire, contained in a reservoir through which the fuel passes. This signal, along with temperature compensation inputs, is then fed to an integral microprocessor, which provides a voltage output proportional to the methanol concentration of the fuel. The Powertrain Controller uses this information to modify injector pulse width and provide proper spark advance. This paper will explain the sensor's development methodology and function.

A new combustion pressure sensor capable of measuring the combustion pressure in an engine cylinder has been developed. This combustion pressure sensor has been used for control of the advanced lean combustion engine in TOYOTA 1992 model (Oct. 1992). The control system is useful for improvement of energy consumption efficiency and reduction of emissions from commercial cars. The successfully designed combustion pressure sensor has excellent features of low impedance and good linearity. It has been realized with the smallest number of components and reasonable cost. This paper describes the principle, structure and basic characteristics of the combustion pressure sensor.