Designing and Optimizing Side-View Mirrors
Examensarbete för masterexamen
Automotive engineering (MPAUT), MSc
Today, reducing the carbon dioxide emissions is vital. The car industry has a responsibility to reduce the fuel consumption and will thereby reduce carbon dioxide emissions. One of the main questions in the automotive industry how to go about this. One possibility is to change the propulsion system. Another option is to reduce the aerodynamic drag of the car; the topic of this thesis. The drag is of great importance when it comes to velocities over 60 kph. There are many parts of the car that contribute to drag. One such part is the (side-view) mirrors. The mirrors increase the total amount of drag by 2-7 percent. There numerous regulations and legal demands when it comes to mirrors due to the aspects of safety. Moreover, the mirrors affect the soiling of the windows which creates yet another safety issue. Dirty windows reduce the visibility for the driver. Many different mirror designs and parameters have been investigated. To get the amount of drag, computer simulations (CFD) have been done. The car which the mirrors have been attached to is a Mercedes-Benz A-class (W168) quarter scale model. Wind tunnel testing (at FKFS, Stuttgart) in quarter scale has been done for correlation. (The correlation did not match the CFD well, however, the trends were the same.) After various tests, one can observe that small changes to the mirror, such as change edges radius, inclinations, adding gutters, and edges, affect the flow both around the mirror and in the rear of the car. The best drag reduction was achieved when the housing curvature of the mirror was changed from rather bulky to flatter model which produced the same drag reduction as having no mirrors at all. The mirror plays a major role in drag contribution for the entire car and therefore mirror optimization is considered very important. Mirror optimization is not an easy task due to uncertainties in the CFD simulations of a few drag counts which makes it impossible to trust all findings. In order to find a good mirror design, a combination of wind tunnel testing in full scale, and CFD simulations is necessary. Mirror design optimization shows great potential.
Energi , Grundläggande vetenskaper , Hållbar utveckling , Innovation och entreprenörskap (nyttiggörande) , Transport , Övrig teknisk mekanik , Energy , Basic Sciences , Sustainable Development , Innovation & Entrepreneurship , Transport , Other engineering mechanics