Rapid Aerodynamic Development of Two-Volume Vehicle Shapes 2000-01-0488
The objective behind this effort is rapid aerodynamic development of vehicle themes, in the early stages of vehicle development. This paper describes a process that is suitable for the development of two-volume (or two-box) vehicle shapes (such as station wagons, minivans or sports utility vehicles).
Traditionally, aerodynamic development at this stage is accomplished using wind-tunnel tests of full or partial scale test models or relying on simulations of aerodynamics employing computational fluid dyanmics (CFD). In either case, the process is not particularly effective in sustaining the desired level of communication between designers (engaged in styling activities) and engineers (engaged in packaging and aerodynamics). A key drawback here is the delay in the generation of aerodynamic drag estimates for the proposals under consideration through use of wind-tunnel tests or CFD computations.
The system described here was developed at the GM R&D Center and employs non-linear neural networks based on various vehicle shape parameters. The system allows simplified on-screen editing of the vehicle theme and instantaneous estimates of an aerodynamic drag index. This allows visual inspection of any proposed vehicle theme (represented by a simplified surface model) for aesthetic “performance” together with simultaneous estimates of its aerodynamic drag potential. The dialog between stylists and engineers is therefore considerably enriched.
The surfaces of these design proposals may be exported in standard formats and used for further refinement (for aesthetic development) and study (using wind-tunnel tests and CFD analyses). This process has been exercised for multiple low-drag concept vehicles and this allowed validation of the process and the tools.