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In use cars often drive through the wakes of other vehicles. It has long been appreciated that this imposes a fluctuating onset flow which can excite a structural response in vehicle panels, particularly the bonnet. This structure must be designed to be robust to such excitation to guarantee structural integrity and maintain customer expectations of quality. As we move towards autonomous vehicles and exploit platoons for drag reduction, this onset flow condition merits further attention. The work reported here comprises both measurements and simulation capturing the unsteady pressure distribution over the bonnet of an SUV following a similar vehicle at high speed and in relatively close proximity. Measurements were taken during track testing and include 48 static measurement locations distributed over the bonnet where the unsteady static pressures were recorded.

Mechatronics development continues to be a challenge for automotive OEM's and suppliers. Multi-disciplinary collaboration and development is critical, especially as architectures and solutions evolve in the automotive industry to satisfy changing needs of the customer and environment. New approaches to mobility, sustainment, and infotainment create the need for new combinations of electrical, software, mechanical, and chemical know-how. Whereas most frameworks for requirements-driven model-based design support a single discipline, what is really needed is a framework for requirements-driven model- based design that can capture the multi-disciplinary architecture of the vehicle or system. This would and allow development organizations to then further decompose the objects in support of further refinement and validation.

It is particularly easy to get tunnel vision as a domain expert, and focus only on the improvements one could provide in their area of expertise. To make matters worse, many Original Equipment Manufacturers (OEMs) are silo-ed by domain of expertise, unconsciously promoting this single mindedness in design. Unfortunately, the successful and profitable development of a vehicle is dependent on the delicate balance of performance across many domains, involving multiple physics and departments. Taking for instance the design of a Heating, Ventilation & Air Conditioning (HVAC) system, the device’s primary function is to control the climate system in vehicle cabins, and more importantly to make sure that critical areas on the windshield can be defrosted in cold weather conditions within regulation time. With the advent of electric and autonomous vehicles, further importance is now also placed on the energy efficiency of the HVAC, and its noise.

For fuel cell vehicles, it is essential that the hydrogen tank be both compact and have sufficient hydrogen to ensure reasonable driving range for which there is a need to pressurize the hydrogen in the tank at levels much higher than that of atmospheric pressure. Furthermore, fast filling is an important consideration in order to minimize time to refuel hydrogen in the tank. In this article, we investigate a Computational Fluid Dynamics (CFD) methodology to see whether we can simulate the fast filling of the hydrogen tank. We performed simulations on an existing validation case using coupled simulation approach between the PowerFLOW® flow solver and PowerTHERM® the thermal solver. For an accurate simulation at elevated pressure levels, we implemented a real gas behavior that is more accurate than the ideal gas equation of state for under these conditions. We observe good agreement with experimental data for both bulk and local variations in temperature.

Selective Catalytic Reduction (SCR) is a process where one injects an aqueous solution of urea into a diesel exhaust system in order to reduce NOx emissions. The urea solution known as AdBlue® or Diesel Exhaust Fluid (DEF) is stored in a DEF Tank that can under cold weather conditions freeze over. Since AdBlue® is unusable while frozen, we use heaters installed in the tanks to melt AdBlue® with government regulations mandating time required to melt AdBlue® in the tank. In this article, we investigate whether a CFD (Computational Fluid Dynamics) based methodology can accurately evaluate time required in melting AdBlue® for a given DEF Tank and heater coil design for a production vehicle as per standard testing procedure. Simulations used a coupled methodology with PowerFLOW® as the flow solver and PowerTHERM® as the thermal solver. The flow simulation did require an accurate modelling of phase change from solid to liquid for AdBlue®.

Windscreen wipers are an integral component of the windscreen cleaning systems of most vehicles, trains, cars, trucks, boats and some planes. Wipers are used to clear rain, snow, and dirt from the windscreen pushing the water from the wiped surface. Under certain conditions however, water which has been driven to the edge of the windscreen by the wiper can be drawn back into the driver’s field of view by aerodynamic forces introduced by the wiper motion. This is wiper drawback, an undesirable phenomenon as the water which is drawn back on to the windscreen can reduce driver’s vision and makes the wiper less effective. The phenomena of wiper drawback can be tested for in climatic tunnels using sprayer systems to wet the windscreen. However, these tests require a bespoke test property or prototype vehicle, which means that the tests are done fairly late in the development of the vehicle.

This paper presents an aerodynamic degradation study of an iced airfoil, using the Lattice Boltzmann approach with the commercial software PowerFLOW. Three-dimensional numerical simulations were performed with an extruded constant section of the GLC-305 airfoil with a leading-edge double-horn ice shape using periodic boundary conditions. The freestream Reynolds number, based on the chord, is 3.5 million and the Mach number is 0.12. An extensive comparison of the main flow features with experimental data is performed, including aerodynamic coefficients, pressure coefficient distributions, velocity and turbulence contours along with its profiles at several positions, and stagnation streamlines. The drag coefficient agrees well with experiments, in spite of a small shift. Two different wind tunnel measurements, using different measurement techniques, were compared to the CFD results, which mostly stayed in between the experimental data.

Regulations that limit emissions of pollutants from gasoline-powered cars and trucks continue to tighten. More than 75% of emissions through an FTP-75 regulatory test are released in the first few seconds after cold-start. A factor that controls the time to catalytic light-off is the heat capacity of the catalytic converter substrate. Historically, substrates with thinner walls and lower heat capacity have been developed to improve cold-start performance. Another approach is to increase porosity of the substrate. A new material and process technology has been developed to significantly raise the porosity of thin wall substrates (2-3 mil) from 27-35% to 55% while maintaining strength. The heat capacity of the material is 30-38% lower than existing substrates. The reduction in substrate heat capacity enables faster thermal response and lower tailpipe emissions. The reliance on costly precious metals in the washcoat is demonstrated to be lessened.

We developed a windshield washer system that enhances washing performance while maintaining low consumption of windshield washer fluid. The system reduces user stress by shortening the amount of time required to remove dirt and maintaining visibility through the windshield. We analyzed the mechanism through which the windshield wiper and windshield washer remove dirt from the glass surface to improve cleaning efficiency. The mechanism consists of a sequence in which the windshield washer fluid splashes down on the glass surface and lifts dirt which is then wiped away by the windshield wiper blade. We defined the amount of windshield washer fluid needed and the time from splashdown to wiping required to lift dirt and wipe it away with the wiper. Based on this mechanism, we developed a wiper arm with built-in washer nozzles.

Amidst the rising demand to reduce CO2 and other greenhouse gas emissions in recent years, gasoline homogeneous-charge compression ignition (HCCI) has gained attention as a technology that achieves both low NOx emissions and high thermal efficiency by means of lean combustion. However, gasoline HCCI has low robustness toward intracylinder temperature variations, therefore the problems of knocking and misfiring tend to occur during transient operation. The authors verified the transient operation control of HCCI by using a 4-stroke natural aspiration (NA) gasoline engine provided with direct injection (DI) and a variable valve timing and a lift electronic control system (VTEC) for intake air and exhaust optimized for HCCI combustion. This report describes stoichiometry spark ignition (SI) to which external exhaust gas recirculation (EGR) was introduced, HCCI ignition switch control, and changes in the load and number of engine revolutions in the HCCI region.

Predicting Exterior Water Management is important for developing vehicles that meet customer expectations in adverse weather. Fluid film methods, with Lagrangian tracking, can provide spray and surface water simulations for complex vehicle geometries in on-road conditions. To cope with this complexity and provide practical engineering simulations, such methods rely on empirical sub-models to predict phenomena such as the film stripping from the surface. Experimental data to develop and validate such models is difficult to obtain therefore here a high-fidelity Coupled Level-set Volume of Fluid (CLSVOF) simulation is carried out. CLSVOF resolves the interface of the liquid in three dimensions; allowing direct simulation of film behaviour and interaction with the surrounding air. This is used to simulate a simplified wing-mirror, with air flow, on which water is introduced.