A minimal-order model of porpoising in race cars and methods for suppressing it

This study explores the phenomenon of ‘porpoising’, a combined heave and pitch motion triggered by fluid-structure interaction, notably affecting high-speed boats and race cars. Porpoising became a significant concern in Formula 1 racing following 2022 regulatory changes that allowed greater exploitation of the car floor to enhance downforce. This study highlights the aerodynamic stability challenges in race cars, arising from the nonlinear dependence of downforce on ride height. A minimal-order model is introduced as a computationally efficient tool to examine the emergence of porpoising and identify potential suppression strategies. The model adeptly captures the system dynamics leading up to stability loss, providing valuable insights while acknowledging the complexity of phenomena such as boundary layer separation. Since the model is only two-dimensional, it is suitable for rapid analytical and numerical investigation, enabling the exploration of various suppression methods. This approach offers a cost-effective solution for addressing complex aerodynamic problems. The study tests the application of a tuned mass damper for stabilising the system, finding it ineffective unless a large damper mass is used, which is impractical for race cars. Subsequently, a suspension system with nonlinear piecewise damping is proposed, demonstrating effective suppression of porpoising at high speeds with moderate system adjustments. This is particularly useful, since it not only makes porpoising suppression possible, but it also allows for more optimisation to enhance performance with passive devices that leverage viscous effects in dampers. Overall, this study advances our understanding of porpoising and aeroelastic stability in race cars, presenting practical solutions to enhance stability and performance. The methodology proposed here can be extended further by including more complicated aerodynamic models, by fitting analytic formulas to computational fluid dynamics results. These extensions would allow for the investigation of more transient dynamics of porpoising vibrations.