1. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Drag reduction on passenger cars through wake control and optimization Lennert Sterken October 8 th, 2014 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

2. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Drag reduction on passenger cars through wake control and optimization Time period: Q1 2011 – Q1 2015 Main participants: Volvo Car Group, Energimyndigheten Program: FFI Energi & Miljö, with 3 600 000 SEK 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

3. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars content Introduction Drag reduction: rear-end extensions Numerical approach Experimental correlation Unsteady methodology development Numerical simulations Differential pressure sensors Future work 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

4. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars introduction Main research question: How can the rear wake be controlled and optimized such that the air resistance is reduced and that fuel consumption and CO 2 -emissions are lowered? 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

5. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Introduction Improvement on UB to make rear-end changes more effective 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014 Red: Side panels Blue: Tunnel panel Green: Suspension panel Yellow: Diffuser panel Orange: Engine-bay connection panel

6. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Rear-end extensions Initial numerical investigation Steady-state (RANS) Realizable k- ε turbulence modelling Extension design: Straight vs. curved Different lengths: 250mm, 150mm and 50mm Inclination change 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

7. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Wind tunnel correlation Rapid prototyping of extension parts Multiple segments Upper segments able to change angle 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

8. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Effect on C D 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014 Reference: Improved underbody and closed cooling

9. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Current investigation New wave-like extensions, tested in CFD Further reduction of drag at 0° yaw Stimulate break-up of the large flow structures 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

10. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Unsteady development Continuation of unsteady simulations Based on a DDES-approach with Spalart-Allmaras turbulence modelling Development on closed-front configurations summarized for publication in journal Further development of simulations with the inclusion of engine-bay 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

11. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Unsteady development Purchase of differential pressure sensors Combined with Ipetronik DAQ-system available at Volvo Cars First measurements conducted July Will be presented at SAE World Congress 2015, Detroit Post-processing based on FFT-analysis and POD-analysis 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

12. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Future work Analysis of unsteady measurements and simulation results Multiple techniques: FFT,POD, … Investigation of extension-shape design, limited to 50mm extension length Preliminary date for PhD defence: June 5 th 2015 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014

13. Energirelaterad fordonsforskning konferens - Drag reduction on passenger cars Thank you for your attention 2014-10-08 Lennert Sterken, Energirelaterad Fordonsforskning - Drag Reduction on Passenger Cars, 2014