High Fidelity Quasi Steady State Aerodynamic Model Development and Effects on Race Vehicle Performance Predictions

Presented in this paper is a procedure to develop a high fidelity quasi steady state aerodynamic model for use in race car vehicle dynamic simulations and its application in a race vehicle multi-body full lap simulation. Developed to fit quasi steady state (QSS) wind tunnel data, the aerodynamic model is regressed against three independent variables: front ground clearance, rear ride height, and yaw angle. An initial dual range model is presented and then further refined to reduce the model complexity while maintaining a high level of predictive accuracy. The model complexity reduction decreases the required amount of wind tunnel data thereby reducing wind tunnel testing time and cost. The quasi steady state aerodynamic model for the pitch moment degree of freedom is systematically developed in this paper. This procedure is extended to the other five aerodynamic degrees of freedom to develop a complete, high fidelity, six degree of freedom quasi steady state aerodynamic model. This high fidelity model reduces the QSS aerodynamic fit error compared to conventional aerodynamic model development. Both the newly developed high fidelity aerodynamic model and a conventionally derived aerodynamic model are implemented in a NASCAR Truck multi-body, full lap QSS simulation to determine the effects of the high fidelity QSS aerodynamic model on the simulation results. Performance metrics are calculated from simulation results and compared to assess the effects of the aerodynamic models on the performance predictions. The increased accuracy of the high fidelity aerodynamic model is found to have discernable effects on the vehicle performance predictions resulting from the QSS simulation.