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This work presents a second series of turbulence measurements made in a range of different on-road terrains and traffic conditions. Wind measurements were captured using a rake of four separate multi-hole pressure probes mounted to the front of a test vehicle traveling at a road speed of 100 km/h. Analysis of the data shows how the turbulence intensities and length scales are modified by terrain type, road side obstacles and the upstream wakes of other moving vehicles. A vertical ‘profile’ of turbulence near the ground is generated and spatial correlations between probes are examined. These on-road results are then compared to the turbulence levels generated by the Monash University wind tunnel. A new method and a series of targets are then proposed for improving the modeling of turbulence in automotive wind tunnels.

The turbulent environment experienced by ground vehicles is currently not well understood. Due to this, and other historical reasons, the aerodynamic testing of automobiles is usually conducted in extremely low-turbulence wind tunnels (<1%), which is in clear contradiction with the small amount of wind data available to date for these heights. This work presents a series of turbulence measurements made in a range of different on-road terrains and traffic conditions. This data was captured using multi-hole pressure probes mounted to the front of a test vehicle traveling at a road speed of 100 km/h. Analysis of the data shows how both the turbulence intensities and turbulent length scales are modified by terrain type, road side obstacles and the upstream wakes of other moving vehicles

The measured on-track performance of a Formula SAE car with a high downforce aerodynamics package is presented. Data logged from variety of different driving tests is used to determine how the addition of ‘wings’ affects the car's acceleration, cornering, braking and slaloming abilities. These results are then compared with analytical predictions for the same car, presented in earlier papers [1, 2].

This review paper presents an analytical framework for measuring the turbulent environment of ground vehicles, motor cars in particular, both on the road and in wind tunnels. It is suggested that this framework can be used to start to measure and assess the level of modeling required of the natural wind environment of motor cars and the turbulent environment needed in wind tunnels. This approach should also be adopted for vehicle aerodynamics and associated acoustics problems and computational fluid dynamics simulation. This approach should also supply the framework by which the importance of turbulence for vehicle aerodynamics can be rigorously assessed.

The detail design and development of a high downforce aerodynamics package for a Formula SAE car is described. Numerical methods are first used to develop multi-element wing profiles which conform to FSAE rules while still generating high negative lift coefficients. A range of full scale wind tunnel testing data is presented for these designs, demonstrating their performance, both in isolation (free-stream), and on the car. Three different techniques are also developed for measuring the performance of a front wing in ground effect.

The initial design of an aerodynamics package for a Formula SAE car is described. A review of Formula SAE rules relating to aerodynamics is used to develop realistic parameters for the specification of front and rear inverted airfoils, or ‘wings’. This wing package is designed to produce maximum downforce within the stated acceptable limits of increased drag and reduced top speed. The net effect of these wings on a Formula SAE car's performance in the Dynamic Events is then predicted. A companion paper [1] describes in detail, the CFD, wind tunnel and on-track testing and development of this aerodynamics package.

Vehicle aerodynamic development is normally undertaken in smooth flow wind tunnels. In contrast, the on-road environment is turbulent, with variations in the relative velocity experienced by the moving vehicle caused mainly by the effects of atmospheric turbulence. In this review the turbulence inherent in the atmosphere is considered, following the approach of wind engineers. The variations of atmospheric wind velocity with time, height, terrain and thermal stratification are summarised and discussed. Statistical parameters presented include mean velocity, turbulence intensities, spectra and probability density functions. The resulting fluctuating approach flow (relative velocity) of the moving vehicle is then considered. The effect of the fluctuating velocity field on parameters of interest to vehicle aerodynamicists (such as aerodynamic noise) are made.

For high-speed driving conditions, the air flow around a car creates wind noise that is transmitted into the cabin, which can dominate other noises. If an atmospheric wind is present, it will create a turbulent cross wind, which not only changes the air flow velocity and direction as experienced by the vehicle, but leads to continuously varying wind noise, as heard inside the car. The purpose of this paper is to look at how the on-road wind environment affects wind noise, and to evaluate the need to simulate real on-road conditions such as fluctuating yaw angles and velocities in vehicle wind tunnels.