Development of CFD Methodology for Drag Force Prediction on Passenger Car with Rear Mounted Spoiler

摘要

Eaton has supported the design and development of spoilers for automobile applications. Addition of spoilers in the car influences the external aerodynamics and in turn impacts fuel economy and vehicle stability, in addition to providing improved external aesthetics. With the upward trend in fuel prices, it becomes more critical to quantify the effect of spoiler on the fuel economy. Eaton Corporation has undertaken efforts to establish predictive capability for evaluating the effect of a rear mounted spoiler on fuel economy. A first phase of these efforts focuses on development of a CFD methodology on the Ahmed Reference model and validation with wind tunnel testing. A second phase will focus on leveraging the methodology on an actual automobile and in the last phase, fuel economy models will be built using outputs from the CFD methodology. This paper focuses on detailed discussion about first phase of the work and summary of the second phase. It includes findings from literature surveys, brief details of wind tunnel testing, observations from sensitivity studies of key CFD modeling parameters and CFD model validation with wind tunnel test data. It has been observed that the finalized CFD modeling approach is able to predict drag forces with an accuracy level of greater than 90% when compared to wind tunnel test data for eight operating conditions.