1. Ben Falconer b.p.falconer@warwick.ac.uk Supervisors: Peter Bryanston-Cross, Brenda Timmerman

2. Credit: AEF Quieter Aircraft –96EPNdB for night takeoff/landing –Noise produced by turbulence close to engine Why? Credit: Steve Allen

3. Turbulence produces noise –Far field noise produced close to engine –Affected by area under wing –Dependent on velocities Far Field Noise Turbulence strength Number of readings Velocity fluctuation

4. Particle Image Velocimetry? Velocimetry ( ˌ v ɛ lə ˈ s ɪ m ɪ tr ɪ ) n. The measurement of the velocity of fluids Abbreviated to PIV

5. Seed flow Illuminate Take images Cross correlate How PIV Works Credit: LaVision

6. 2 Cameras Resolves 3 components Angle to focal plane –Optimum θ=45° Stereo PIV

7. Focus on non-perpendicular planes Lens held at angle Scheimpflug Principle

8. One of the largest anechoic chambers in The World –27m x 26m x 16m –Large scale tests 1:10 Noise Test Facility Credit: QinetiQ

9. No one enters during tests –Control centre 200m away Expensive –£10,000/hour Compressor –400m/s Noise Test Facility Credit: QinetiQ

10. Flow moving 400m/s Can’t get close –But particles only 0.3µm Remote operation Must be fast Full range of distances In Practice

11. 4m x 2.6m x 4.7m Around flightstream 2.7m optical standoff Mounted on 2D traverse Bi-directional Full Range Rig

12. Enables viewing 2 targets –For parallel planes –Preserves stereo Mirrored Scheimpflug

13. 4m x 2.6m x 4.7m Around flightstream 2.7m optical standoff Mounted on 2D traverse Bi-directional Full Range Rig

14. Cameras moved –View under wing Lasers moved –Avoids wing Upstream Stereo view Wing Rig

15. Hostile conditions –Vibrations kill hard drives Remote access Data throughput –Images are acquired at 60MB/s per camera –Theoretical max 125MB/s on gigabit Ethernet –80MB/s with overheads Computer System

16. Control computer –Synchronises cameras and lasers –Accurate to nanosecond scale Solid state computers –Close to cameras –Not affected by vibrations –Low storage capacity Rig Computers

17. Storage servers –Dedicated gigabit Ethernet each –~3.5TB per server –Away from vibrations Control Room

18. 2 Control computers –1 or 2 person operation –Calculate 880,000 run parameters –Organise 40TB of resulting data Control Room

19. Velocity maps –Time averaged Results

20. Turbulent kinetic energy –Indicates variation in velocity Closest measurement to actual acoustics Results Velocity fluctuation

21. Questions?

22. Correlation between axes Can be extended to rotation What’s Next?

23. Out of plane rotation What’s Next?

24. Computer System

25. Additions to base system –Mirrors –Focusing –CCTV –Remote power

26. 880,000 measurements –1100 measurements per position –20 positions per condition –40 conditions 40TB of data –3 Cameras –16MB per image –880,000 measurements Configurations