Prediction of Formula 1 Engine and Airbox Performance using Coupled Virtual 4-Stroke and CFD Simulations

This paper describes a technique whereby race car airbox performance can be assessed directly in terms of predicted engine performance by coupling a one-dimensional engine model on a timestep-by-timestep basis to a three-dimensional computational fluid dynamics (CFD) model of an airbox. A high-performance three-litre V10 engine was modelled using Virtual 4-Stroke unsteady gas dynamics engine simulation software, while two airbox configurations, representative of those used in FIA Formula 1 (F1), were modelled using general purpose CFD software.

Results are presented that compare predicted engine performance for the two airbox geometries considered in the coupled simulations. Individual cylinder performance values are also presented and these show significant variations across the ten cylinders for each airbox simulated. CFD results show that pressure waves propagating from the bellmouths of the inlet trumpets produce highly complex and unsteady flows in airboxes, including reverse flow at the inlet trumpets. The results demonstrate the sensitivity of the coupled engine and airbox simulation technique to changes in airbox geometry, and also emphasize the three-dimensional and transient nature of the airflow in an airbox that is connected to a breathing engine. The limitations of steady flow airbox CFD simulations are highlighted when compared to the coupled simulations. It is concluded that a one-dimensional engine model coupled to a three-dimensional CFD model is an extremely effective method of predicting Formula 1 engine and airbox performance.