1. Ski-Wing
Bruno Ferreira, Melker Nordqvist
Transport ground vehicles are one of the most used transport
system existing today and. For that reason, many people tend
to take their car on their winter vacation to the mountains
where the roads are icy and slippery. To improve safety for
the travelers in the car and on the roads it is of great
importance to improve the traction of the car.
It is known that, for high speeds, bodies tend to create a lift
force due to the pressure gradient created between their
lower and upper surfaces. If this lift force gets too high, it
could impact in the loss of traction of the vehicle and
therefore in a loss of the control and possible accident.
One device that could be used in order to compensate this lift
force without adding extra weight to the vehicle is the spoiler.
This device acts like an upside-down wing, creating a force
downwards and keeping the traction under control. It is
important to notice that those devices could have a negative
impact in the drag, which leads to a higher fuel consumption
since the engine has to produce more power to compensate
this extra drag.
INTRODUCTION
OBJECTIVE
The objective of this study is to design a spoiler in a manner
that the vehicle stays controllable for high speeds without
increasing too much the resultant drag.
METHODOLOGY
• ANSYS CFX.
• Compute values for lift and drag coefficients for all
surfaces on car and spoiler for comparison.
• Three different spoiler positions – Top of slope, at the rear
of the slope and the last one in between.
• Factor to decide spoiler was the one with lowest L/D ratio
• Study of flow field by use of streamlines.
• Car dimensions 1044x389x288mm.
SPOILER DESIGN
• Three simplified
Carving skis.
• Different angles
between the skis to
create a ”camber”.
• Aero technology
”Flap configuration”
• Total size of the box
containing the skis:
60x380x35mmFigure 1: Chosen spoiler configuration
RESULT AND DISCUSSION
Spoiler Without Rear Middle Top
𝐶 𝑑 0.3347 0.4213 0.5298 0.5113
𝐶𝑙 0.1003 0.1094 -0.1734 -0.0415
𝐿/𝐷 0.2995 0.2598 -0.3273 -0.0812
Figure 2: Illustrates the flow field around the car without spoiler (left) and
the one with spoiler (right). Notice the increased bubble size behind the
car created by the spoiler, resulting in more drag.
Table 1: Illustrates the values of 𝐶 𝑑 𝑎𝑛𝑑 𝐶𝑙 for the different
locations of the spoiler.
L/D ratio is an aerodynamic efficiency that defines how much
lift can be generated with a certain amount of drag. A higher
value results for better efficiency. However, downforce is
preferable in this case, so, the L/D should be negative and high.
Therefore, by examining table 1, it is possible to observe that
the best spoiler is the middle one. It should be noted that this
configuration creates 58% more drag due to the larger wake
created by the spoiler (figure 2) than the car without spoiler.
This is deemed acceptable since it creates 273% more
downforce than the one without.
CONCLUSION
• Improved driving performance and safety due the better
traction on the car.
• Increased fuel consumption due to more drag.
• With the selected spoiler it was possible to achieve the
proposed objective.
ABSTRACT
This study intends to design a spoiler making use of skis, in order to reduce the risk of accidents on the roads by improving the driving performance of a car. To
achieve that, simulations were ran with the help of ANSYS CFX, where different configurations were analysed until a design was conceived. The improvements
made in the performance were measured by the lift and drag coefficients, which were compared then to a body in the absence of the spoiler. The outcome of
the study was very satisfactory, resulting in an improvement of more than 250% in downforce, in spite of a negative outcome for the drag.