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There are a number of numerical and experimental studies of the aerodynamic performance of wheels that have been published. They show that wheels and wheel-housing flows are responsible for a substantial part of the total aerodynamic drag on passenger vehicles. Previous investigations have also shown that aerodynamic resistance moment acting on rotating wheels, sometimes referred to as ventilation resistance or ventilation torque is a significant contributor to the total aerodynamic resistance of the vehicle; therefore it should not be neglected when designing the wheel-housing area. This work presents a numerical study of the wheel ventilation resistance moment and factors that affect it, using computational fluid dynamics (CFD). It is demonstrated how pressure and shear forces acting on different rotating parts of the wheel affect the ventilation torque. It is also shown how a simple change of rim design can lead to a significant decrease in power consumption of the vehicle.

The foremost aim of the work presented in this paper is to improve fuel economy and decrease CO2 emissions by reducing the aerodynamic drag of passenger vehicles. In vehicle development, computer aided engineering (CAE) methods have become a development driver tool rather than a design assessment tool. Exploring and developing the capabilities of current CAE tools is therefore of great importance. An efficient method for vehicle shape optimization has been developed using recent years' advancements in neural networks and evolutionary optimization. The proposed method requires the definition of design variables as the only manual work. The optimization is performed on a solver approximation instead of the real solver, which considerably reduces computation time. A database is generated from simulations of sampled configurations within the pre-defined design space. The database is used to train an artificial neural network which acts as an approximation to the simulations.

In the early stages of an aerodynamic development programme of a road vehicle it is common to use wind tunnel scale models. The obvious reasons for using scale models are that they are less costly to build and model scale wind tunnels are relatively inexpensive to operate. It is therefore desirable for model scale testing to be utilized even more than it is today. This however, requires that the scale models are highly detailed and that the results correlate with those of the full size vehicle. This paper presents a correlation study that was carried out in the Chalmers and Volvo Car Aerodynamic Wind Tunnels. The aim of the study was to investigate how successfully a correlation of the cooling air flow between a detailed scale model and a real full size vehicle could be achieved. Results show limited correlation on absolute global aerodynamic loads, but relative good correlation in drag and lift increments.

Automotive wind tunnel testing is a key element in the development of the aerodynamics of road vehicles. Continuous advancements are made in order to decrease the differences between actual on-road conditions and wind tunnel test properties and the importance of ground simulation with relative motion of the ground and rotating wheels has been the topic of several studies. This work presents a study on the effect of active ground simulation, using moving ground and rotating wheels, on the aerodynamic coefficients on a passenger car in yawed conditions. Most of the published studies on the effects of ground simulation cover only zero yaw conditions and only a few earlier investigations covering ground simulation during yaw were found in the existing literature and all considered simplified models. To further investigate this, a study on a full size sedan type vehicle of production status was performed in the Volvo Aerodynamic Wind Tunnel.

A primary goal within the industry is to shorten the lead time to get shorter time to market and lower cost. System verification can set the limits for how short the lead time can be. Traditionally verification of automotive communication systems like Remote Keyless Entry, RKE, is performed in a complete vehicle late in the product development process. To fulfill the quality demands during the shorter project time Volvo Cars, VCC, has experienced that it is necessary to develop new requirements and verification methods. Six Sigma contains a complete toolbox to do this in a structured and time efficient way. VCC has together with other Ford Motor Company, FMC, brands and the supplier Continental developed methods and requirements so that the RKE system can be verified before vehicles are built. Only a last validation has to be performed in a complete vehicle.

This study focus on the aerodynamic influence of the engine bay packaging, with special emphasis on the density of packaging and its effect on cooling and exterior flow. For the study, numerical and experimental methods where combined to exploit the advantages of each method. The geometry used for the study was a model of Volvo S60 sedan type passenger car, carrying a detailed representation of the cooling package, engine bay and underbody area. In the study it was found that there is an influence on the exterior aerodynamics of the vehicle with respect to the packaging of the engine bay. Furthermore, it is shown that by evacuating a large amount of the cooling air through the wheel houses a reduction in drag can be achieved.

This paper reports how numerical simulation can be used as a tool to guide vehicle design with respect to brake cooling demands. Detailed simulations of different brake cooling concepts are compared with experimental results. The paper consists of two parts. The first part places the emphasis on how to model the flow inside and around the brake disc. The boundary layer and the pumping effect is investigated for a ventilated single rotor. The numerical results will be compared to experimental results. In the second part, an engineering approach is applied in order to rank different technical solutions on a Volvo S80 vehicle in terms of brake cooling and aerodynamic drag. The results from the free brake disc simulations indicate that the tangential velocity can be predicted with high accuracy, e.g. standard k-ε model with prism near wall cells typically within 4% of measured data.

Flexible car body production, including prototyping, is one answer to the market targets where customers ask for an increasing number of models / variants and shorter lead time. The in-house interests of car builders are, besides investment and manpower flexibility, also improved product quality. Quality in body in white is mainly related to geometry (= high precision), to make sure that the final assembly shops will have the right conditions to keep customers satisfied (flush in doors, hood, fenders etc.). The consequences are that both the product and the process equipment have to be in a stable condition to guarantee low spread in the complete car-body. CAD technology is one of the keys to reach this goal, where: Off-line tooling Off-line programming Flow simulation Measurement strategy, off-line / in-line are the main powerful tools to reduce lead time as well as costs.

This paper reports an investigation of the association between flame kernel movement and cyclic variability and assesses the relative importance of this phenomenon, with all other parameters that show a cyclic variability held constant. The flame is assumed to be subjected to a “random walk” by the fluctuating velocity component of the flow field as long as it is of the order of or smaller than the integral scale. However, the mean velocity also imposes prefered convection directions on the flame kernel motion. Two-point LDA (Laser Doppler Anemometry) measurements of mean velocity, turbulence intensity and integral length scale are used as input data to the simulations. A quasi-dimensional computer code with a moving flame center position is used to simulate the influence of these two components on the performance of an S I engine with a tumble-based combustion system.

Legal producer responsibility for end-of-life vehicles will be introduced in Sweden 1998. In an ongoing 1-year project the conditions tor a producer-dismantler network are developed, aiming at increased recovery. About 5000 cars of 5 makes are treated by 30 dismantlers. Producers (manufacturers and importers) not actively involved participate in an information feedback program. The producer-initiated project develops interaction with existing expertise and experience of management of sometimes conflicting interests. Urgent questions are cost-effectiveness, recovery methods and markets, dismantling instructions, and monitoring methods. The project is expected to expand into a national network of producer-contracted dismantlers, with possibilities for even further expansion.

Under a global impulse for less man-made emissions, the automotive manufacturers search for innovative methods to reduce the fuel consumption and hence the CO2-emissions. Aerodynamics has great potential to aid the emission reduction since aerodynamic drag is an important parameter in the overall driving resistance force. As vehicles are considered bluff bodies, the main drag source is pressure drag, caused by the difference between front and rear pressure. Therefore increasing the base pressure is a key parameter to reduce the aerodynamic drag. From previous research on small-scale and full-scale vehicles, rear-end extensions are known to have a positive effect on the base pressure, enhancing pressure recovery and reducing the wake area. This paper investigates the effect of several parameters of these extensions on the forces, on the surface pressures of an SUV in the Volvo Cars Aerodynamic Wind Tunnel and compares them with numerical results.