Browsing by Author "Sayers, Anthony"

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    Aerodynamics drag reduction of commercial trucks
    (2000) Wang, Cheng; Sayers, Anthony
    This thesis deals with the airflow over a double trailer Gull Wing truck, with a view to reducing the drag of the truck. To investigate the flow over the truck, a 1:20 scale double trailer truck model was designed and constructed from chipboard for wind tunnel experiments. The overall size of the model is 1100 mm long, 130 mm wide and 215 mm high. A same scale numerical model was also built for computational simulations.
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    The effect of the boundary layer present in wind tunnels on the aerodynamic drag of a model truck
    (1997) Lutz, Thomas; Sayers, Anthony
    This thesis deals with a system that reduces the oncoming boundary layer displacement thickness in a wind tunnel. The device is then used to examine the effect that this boundary layer has on the aerodynamic drag of a standard truck, which is classified as a bluff body with a high ground clearance and the same truck fitted with skirts all round, which is then classified as a bluff body with a low ground clearance. To gain insight into this field of industrial aerodynamics, an extensive literature survey was done in which all the relevant SAE papers onwards from the late sixties were studied and summarised in the first section of this report. The second section deals with a system that can limit the boundary layer displacement thickness in the test section of the 3/4 open jet wind tunnel. Through investigations and an extensive literature research a suction device was designed and built. This boundary layer removal system was then tested to ensure that the main flow indicators are not influenced by the suction and thus lie within internationally accepted limits. Included in this section are a description of the truck model and the other instruments or devices used to complete the testing. The third section deals with the aerodynamic drag experienced by the bluff body with a high ground clearance. Included in the third section is an investigation that deals with the aerodynamic drag of the same truck model, when skirting has been added which considerably lowers the ground clearance. The results obtained from the above investigations indicate that the drag of the Ground Simulation model without skirts is increased by about 3.8% with the removal of the boundary layer and up to 10% for the model with the skirts. It is thus shown that the farther the object protrudes into the boundary layer, the larger the increase in drag will be once this boundary layer has been removed. These figures were obtained from testing the model at 22.2m/s free stream velocity and a 6mm wheel-ground clearance, with the wheels rotating.
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    An experimental study of the aerodynamic characteristics of a wing in close proximity to a moving ground plane
    (2006) Rhodes, Steven C; Sayers, Anthony
    A wind-tunnel investigation was conducted to determine the effect of ground proximity on the aerodynamic characteristics of a slender un-cambered DHM1TU rectangular wing of aspect ratio 3. A moving-belt ground plane and elevated aerodynamic balance facility were designed and installed in the UCT McMillan Laboratory open test-section wind tunnel. ... The results indicated that as the ground was approached the wing experienced an increase in the lift-curve slope and a reduction in induced drag, which resulted in an increase in the lift-drag ratio.