A Quasi-Unsteady Description of Windscreen Wiper Induced Flow Structures
- 1. A Quasi-Unsteady Description of Windscreen Wiper Induced Flow Structures Adrian Gaylard Technical Specialist – Aerodynamics & CFD 6 th MIRA International Vehicle Aerodynamics Conference
- 2. Overview Current Work Simplifying Assumptions Flow Structures A Quasi-Unsteady Interpretation Proposed General Flow Structure Conclusions
- 3. Current Work Experimental work: MIRA FSWT “ Aero Buck” and production vehicles. CFD (Exa PowerFLOW ™) 1.1mm characteristic (smallest) Volume Element dimension. “ Bare Screen” Case 42 Million Volume Elements. 6 Million Surface Elements. “ Parked” / ”Mid-Wipe” Cases 108 Million Volume Elements 14 Million Surface Elements
- 4. Simplifying Assumptions This Work Y/Y N N Y N N N N Y Y/N
- 5. Flow Structures Surface Flow, Bare Screen Experiment MIRA FSWT CFD Exa PowerFLOW
- 6. Flow Structures Off-Surface Flow, Bare Screen Vortex Cores (Iso –surfaces of 2 ) Streamlines
- 7. Flow Structures Surface Flow, Parked Experiment
- 8. Flow Structures Surface Flow, Parked CFD
- 9. Flow Structures Off-Surface Flow, Parked Vortex Cores (Iso –surfaces of 2 )
- 10. Flow Structures Off-Surface Flow, Parked Streamlines
- 11. Flow Structures Surface Flow, Mid-Wipe Experiment
- 12. Flow Structures Surface Flow, Mid-Wipe CFD
- 13. Flow Structures Off-Surface Flow, Mid-Wipe Vortex Cores (Iso –surfaces of 2 )
- 14. Flow Structures Off-Surface Flow, Mid-Wipe Streamlines
- 20. Other Vehicles Mercedes SL500
- 21. Other Vehicles Jaguar XJ (Mk3) X350 (2003-2007) Note: (taped) sunroof edges
- 22. Proposed Flow Structure Main Flow Cowl Vortex (Re-attached) Radial Flow Blade/Arm Vortices “ Knuckle” Vortex Vortex paths swept over screen and roof
- 23. Conclusions Coherent vortex structures generated/modified by wipers. Cowl Vortex (modified) Upstream Wiper Vortex Downstream Wiper Vortex Knuckle Vortex Wiper generated vortex structures persist onto the roof. Will be swept laterally across the roof by wiper movement. Aeroacoustic source associated with, but remote from, wiper system. CFD models can provide some insight
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