Vehicle Dynamics Part I: An Aerodynamic Odyssey Jeremy Losaw Advised by Professor Ann Anderson

Introduction Purpose How did I do it? Characterize the flow over a radio controlled vehicle with a NASCAR style body How did I do it? 3 Methods Force balance Pressure taps PIV (Particle Image Velocimetry)

Lift - Dr. Jekyll Lift Downforce (negative lift) increases a tires capability to produce cornering force Down force stabilizes vehicles at high speed Improves braking performance

Drag - Mr. Hyde Reduces top speed Helps chasing cars to draft and catch up Reduces effective power of engine

Why RC Cars Perfect size for the Union wind tunnel Can outfit with many body styles Fast enough that aerodynamics can have an impact on their handling

Juxtaposition Make changes to spoilers each to see effects 4 spoiler configurations full spoiler no spoiler 2 alternate geometries Characterize flow over cars and analyze the results based on the needs for each vehicle

Tools Force Balance Pressure Taps PIV Cumulative lift and drag Local performance characterization PIV Full field validation

Spoiler Geometries Regular Spoiler Spoiler A Spoiler B

The Inspiration

Lift Coefficient Cl = Fl/ (.5 AV2 )

Drag Coefficient Cd = Fd/ (.5 AV2 )

NASCAR Pressure Distribution High pressure at the front and over the trunk Local flow acceleration at the front of the roof

Spoiler Comparison Higher upstream pressures with full spoiler Low pressure with no spoiler Spoiler B has less of and effect on upstream pressure i.e. less drag

PIV Local acceleration consistent with pressure data Stagnation point on nose Recirculation zone behind car

Conclusions RC racecars are suitable for generating qualitative results of the full scale Each of the three methods served to validate each other There is only a slight difference in performance for the different spoiler geometries, but Spoiler B seems to have a slight performance edge

Special Thanks Professor Anderson Stan Gorski Pat Tuccillo Jim Howard