Formula 1 Aerodynamic Assessment by Means of CFD Modelling DANSIS Automotive Fluid Dynamics Seminar 25 March 2015 Copenhagen Denmark Dr. Lesmana Djayapertapa Senior CFD Consultant LR Senergy Aberdeen - UK
Agenda Wind Tunnel (WT) Testing and CFD in Formula 1 Aeroelasticity Analysis Rear Wing Aerodynamic Design CFD-Based Virtual Optimisation Approach Summary
CFD Usage (TFLOPS) Wind Tunnel (WT) Testing & CFD WT is still the main aerodynamic design tool 50% model scale Running 24 hours a day, 7 days a week CFD compliments WT Testing, filters aerodynamic design ideas, possibly steer wind tunnel testing programme F1 teams usually have their own High Performance Computing centre WT wind on weekly testing hours and CFD Usage were (used to be) recorded, and need to be on or below the purple line FOTA Aerodynamic Restriction 45 40 35 FOTA Aero Limit 30 25 20 15 10 5 0 0 10 20 30 40 50 60 70 WT Hours
CFD Usage (Some Examples...) Rear Wing Aerodynamic Design CFD-based Optimisation Nose & Front Wing Pillar Aerodynamic Design Front Wing Aerodynamic Design Front Floor Diffuser Interaction Front Suspension Aerodynamic Design
Aeroelasticity Analysis CAD CFD Model FEA Model Mesh Deformation Displacement Converged? CFD Pressure interpolated from CFD to FEA mesh FEA Displacement (Deformation) Benefits of Aeroelasticity: Increased (Front) Down Force Drag Reduction Better Control of Aerodynamic Balance Final Shape Aerodynamic Balance / Centre Of Pressure / Front Balance Czt FCP AB RCP Czf Wheel base Czr
At 300km/h the airflow past the Front Wing can generate approximately 250kg of down-force per side: FRONT WING AERODYNAMIC LOAD The carbon fibre structure tends to bend under this loading: ~250kg @ 300km/h ~250kg @ 300km/h
FW DEFLECTION Stress analysis (FEA) of the composite structure is used to estimate to amount of deflection under the aerodynamic load: Comparison between design FW position and deflected geometry
DEFLECTED FW LOAD When the FW defects its loading increases (ground effect)... Increased in FW load Need to maintain coherent FW vortices...this also has downstream effect benefits Total car downforce increase can be even more significant
CFD-Based Aerodynamic Design Optimisation
Typical Design Optimisation Flow Chart Initial Design Background Effort Final Design Optimiser Parametric Base Geometry CAD Geometry Rule Bases Results Extraction Search CFD Meshing CSM Boundary Conditions Post Processing CFD + Mesh Deformation + Optimisation
Aim: to further explore the design space, looking for possible design to achieve certain objectives Due to CPU-intensive analysis: Design of Experiment (DoE) Response Surface Model (RSM) Virtual Optimisation
DOE-RSM-(Virtual) Optimisation Cluster Parallel Analysis Initial Geometry DoE CFD CFD CFD CFD CFD CFD CFD CFD CFD CFD CFD CFD Build the Initial Training Database Construct RSM Evaluate RSM Virtual Optimisation Using RSM CFD CFD CFD RSM Tuning Validate the virtual points, and enrich the Training Data base Adequate? Best Design
The Geometry Isolated Rear Wing (RW) RW is not mounted to the race car Inlet flow conditions are obtained from full car run to provide realistic flow condition
Czrw Rear Wing Down force The Design Objective To maximise perpendicular distance from the RW polar line Medium Down force family 78 UPD9_ISOLA_RW UPD9_ISOLA_RW; 15mm Slot Gap High Down force family 77 76 75 74 Distance d BSL Low Down force family 73 +2DEG 72 y = 1.6912x + 34.069 71 RW R² = Polar 1 +4DEG 70 69 21 21.5 22 22.5 23 23.5 24 24.5 25 Rear Wing Drag Cxrw
The Design Parameters Nose height slot gap normal position Slot gap streamwise position 3 parameters per section 3 sections along the span Total 9 design parameters
Volume Mesh Deformation Auto Checks for: Mesh Validity; and Mesh Quality
Maximum Distance The Max Distance Convergence 1 st Loop 2 nd Loop 3 rd Loop DOE Points Baseline Optimisation Loop
Czrw DOE Points Baseline Cxrw
Czrw 1 st Optimisation Loop Baseline Cxrw
Czrw 2 nd Optimisation Loop Baseline Cxrw
Rear Wing Down force 3 rd Optimisation Loop Medium Down force (Max Efficiency) family High Down force family Baseline Low Down force family Rear Wing Drag
Delta Aero Coeff (Points) The Accuracy of the Virtual Design 0.1 Delta Cxrw & Czrw (Virtual Design - Real Design) 0.05 0 1 2 3 4 5 6 7 8 9 10 11 12-0.05-0.1-0.15 Delta Czrw (pts) Delta Cxrw -0.2-0.25-0.3-0.35 Design ID
Rear Wing Shape Changes Baseline
Summary Wind Tunnel Testing and CFD in Formula 1 Front Wing Deflection Analysis using CFD-Structural Coupling Further Exploring Rear Wing Design Space using CFD- Based Virtual Aerodynamic Optimisation
Thank You