Experimental investigation of automobile flow fields for CFD validation purposes

This project is initiated through a collaboration with Multimatic. The performance, handling, safety, and comfort of automobiles are affected by their aerodynamic properties. Traditional tools used by industry to evaluate the aerodynamic performance of automobiles are wind tunnel experiments and road tests. Full-scale experimental testing is expensive and time consuming. The use of scaled models, while less expensive, is subject to flow similarity discrepancies. To meet consumer demand and stay competitive, automotive companies must develop new techniques to avoid the high economic costs and long development times of experimental tests. Computational Fluid Dynamic (CFD) tools have emerged to fill this requirement, as they offer a cost-effective alternative to design optimization. Unfortunately, CFD analysis of automobile flow fields is challenging. The external geometry of automobiles is extremely complex, the flow field is fully three-dimensional and turbulent, and flow separation is common. In order to validate the CFD software, simulation results must be compared with experimental measurements during the development phase. The current research performed at the University of Toronto focuses on high-quality measurements of canonical automobile models for the purpose of CFD validation. The capabilities of the experimental apparatus at the University of Toronto are exceptionally suited toward investigation of this bluff-body flow field. The measurement capabilities are listed below.

  • Determination of the unsteady flow field with a high vector resolution using PIV.
  • Surface static pressure measurements using pressure transducers.
  • Lift and drag forces using force balance.
Results are combined to produce an understanding of the unsteady flow field about automobiles, a topic that is still not understood. In addition, a synthesis of the results provide a comprehensive database of experimental data for which validation of the accuracy/robustness of CFD software for automobile simulations can be performed.