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

1. Systems for High Velocity Particle Image Velocimetry Ben Falconer b.p.falconer@warwick.ac.uk Supervisors: Peter Bryanston-Cross, Brenda Timmerman

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

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

4. Particle Image Velocimetry? Velocimetry (ˌvɛləˈsɪmɪtrɪ) n. The measurement of the velocity of fluids Abbreviated to PIV

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

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

7. ScheimpflugPrinciple • Focus on non-perpendicular planes • Lens held at angle

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

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

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

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

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

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

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

15. Computer System • 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

16. Rig Computers • Control computer • Synchronises cameras and lasers • Accurate to nanosecond scale • Solid statecomputers • Close to cameras • Not affected byvibrations • Low storage capacity

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

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

19. Results • Velocity maps • Time averaged

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

21. Questions?

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

23. What’s Next? • Out of plane rotation

24. Computer System

25. Computer System • Additions to base system • Mirrors • Focusing • CCTV • Remotepower

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