CFD Analysis of the Diffuser of a Formula 3 Racecar

Abstract

The papers primary goal was to examine the aerodynamic behaviour and performance of the diffuser of a Formula 3 racecar within a moving ground plane for critical case situations. The purpose of this investigation was: • To understand the governing factors and physics which are associated with an automotive diffuser within ground proximity. • To examine the effects and association between ride height and ramp angle variance. • To analyse the flow performance associated with the central diffuser section both independently and also as part of the complete diffuser geometry. • To generate and analyse alternative designs based on the current design flow performance and also alternative category designs. This paper focuses on the physics primarily associated with the Formula 3 diffuser geometry itself and to understand how the design of the diffuser and effects of near ground proximity affects the downforce and drag performance. Due to the complexity of the complete Formula 3 diffuser, such as effects from upstream geometry such as splitter and sidepod design, road surface roughness, downstream obstacles (trailing car), rear wheel location, top surface geometry, ride height and car speed. As can be seen from this, the list is endless, and this is before any of the geometry directly associated with the diffuser is considered. So for this the diffuser will be considered using a simplified bluff body configuration. The diffuser study was broken into three stages, a simplified two-dimensional study to provide an understanding of the trend between ride height and associated ramp angle for maximum downforce and reduced drag performance. The central diffuser was then considered independently to analyse the current designs suitability for the desired ride height as was identified during cornering. Finally, the complete diffuser geometry was analysed to verify results obtained for the central study and also visualise the flow patterns associated with the designs and pressure performance.