Aerodynamic Influence Over Leading and Pursuing Motorcycles Equipped With Downforce-Generation Wings

TL;DR

This study examines how aerodynamic wings on motorcycles influence the flow dynamics and stability of pursuing motorcycles, revealing that positioning and vortex interactions significantly affect performance and safety.

Contribution

The paper provides new insights into the aerodynamic interactions between lead and pursuing motorcycles with wings, highlighting the effects of vortex behavior and relative positioning on stability.

Findings

Lateral offset can reduce wheelie tendencies.

Coherent vortices influence the pursuing motorcycle independently of wake turbulence.

Downforce-generating appendices impact stability and should be considered in regulations.

Abstract

The aerodynamic influence of a wing-equipped motorcycle on a pursuing motorcycle presents critical implications for stability and performance. This study investigates the induced flow dynamics, characterized by a turbulent and complex wake that significantly affects the aerodynamic forces and moments experienced by the following motorcycle. The presence of aerodynamic appendices on the leading motorcycle intensifies these effects, generating coherent wingtip vortices that propagate downstream-a typical behavior of lift-generating devices. In this work, numerical simulations reveal that the aerodynamic consequences vary with the relative positioning of the pursuing motorcycle. A lateral offset can reduce wheelie tendencies due to beneficial flow interactions, while lateral alignment and longitudinal positioning variation may exacerbate negative aerodynamic impacts, compromising stability. Contrary to initial expectations, the simulations in this work demonstrate that the turbulent wake and the coherent vortex pair influence the pursuing motorcycle's behavior independently, persisting across all tested relative distances. While the turbulent wake usually creates a low-pressure region that facilitates drafting, the presence of coherent vortices reduces this advantage by introducing additional lift through the upwash velocity component. Conversely, specific lateral deviations can lessen wheelie effects, with downwash becoming the dominant flow component. Although difficult to be removed promptly due to being part of the overall high performance motorcycle design, it is suggested that the downforce generating aerodynamic appendices removal should be considered by the motorcycling competition governing bodies to provide better safety and racing conditions at all categories that make use of it.