2. An experimental setup to investigate intermittency in pipe systems Università degli Studi di Genova Corso di Laurea Magistrale in Ingegneria Meccanica Energia & Aeronautica Relatori: Prof. Alessandro Bottaro Prof. R.I. Sujith Candidato: Diego Zangrillo Luglio 2015

3. Indian Institute of Technology Madras 2 24/07/2015

4. Purpose of the work Investigate Aeroacoustic Intermittency in a very simple experimental setup to understand, predict and avoid it in real systems For example: In compressor stations of gas transport In combustor of aircraft engines In safety valves on boilers 3 24/07/2015

5. Example of events which happened in the past because of Aeroacoustic Instabilities: 4 Oklahoma Gas and Electric Company: safety valves installed on boilers The steam dryer in the boiling water reactor (BWR) of Quad Cities Unit 2 (QC2) 24/07/2015 D. Tonon, A. Hirschberg, J. Golliard and S. Ziada, Aeroacoustics of pipe systems with closed branches, Eindhoven University of Technology, 2010

6. Between chaos and order: Intermittency 24/07/2015 5

7. Experimental Setup 6 Sampling Time= 30 s F s = 10 KHz microphone orifice Settling chamber open end Dimensions: L = 600 mm D = 50 mm d 0 = 10 mm t = 5 mm L c = 300 mm d c = 300 mm 24/07/2015

8. Acquiring System 24/07/2015 7

9. Data Analysis Fast Fourier Transform Hurst exponent Recurrence Plot Recurrence Quantification Analysis 8 24/07/2015

10. In Orifice Case (A) Re = 3097 Ma = 0.014 Case (B) Re = 4588 Ma = 0.021 Case (C) Re = 4818 Ma = 0.022 Case (D) Re = 5047 Ma = 0.023 Case (A) 9 24/07/2015

11. In Orifice Case (A) Re = 3097 Ma = 0.014 Case (B) Re = 4588 Ma = 0.021 Case (C) Re = 4818 Ma = 0.022 Case (D) Re = 5047 Ma = 0.023 Case (B) 10 24/07/2015

12. In Orifice Case (A) Re = 3097 Ma = 0.014 Case (B) Re = 4588 Ma = 0.021 Case (C) Re = 4818 Ma = 0.022 Case (D) Re = 5047 Ma = 0.023 Case (C) 11 24/07/2015

13. In Orifice Case (A) Re = 3097 Ma = 0.014 Case (B) Re = 4588 Ma = 0.021 Case (C) Re = 4818 Ma = 0.022 Case (D) Re = 5047 Ma = 0.023 Case (D) 12 24/07/2015

14. Frequency vs Air Flow Rate vs Amplitude 13 A B C D 24/07/2015

15. Hurst Exponent 14 24/07/2015

16. Hurst Exponent 15 24/07/2015

17. Recurrence Plot 16 24/07/2015 Ref: N. Marwan, M. Carmen Romano, M. Thiel, J. Kurths, Recurrence plots for the analysis of complex systems, University of Potsdam, 2006

18. 17 24/07/2015

19. 18 24/07/2015

20. RQA parameters 19 24/07/2015 Ref: C. L. Webber Jr, J. P. Zbilut, Recurrence Quantification Analysis of Nonlinear Dynamical Systems

21. 20 24/07/2015

22. RQA parameters 21 24/07/2015 Ref: C. L. Webber Jr, J. P. Zbilut, Recurrence Quantification Analysis of Nonlinear Dynamical Systems

23. 22 24/07/2015

24. RQA parameters 23 24/07/2015 Ref: C. L. Webber Jr, J. P. Zbilut, Recurrence Quantification Analysis of Nonlinear Dynamical Systems

25. 24 24/07/2015

26. Conclusions and future developments Intermittency found in a simple aeroacoustic system Need to focus on the first transition Detection of the intermittency type 25 24/07/2015

27. Thanks for your attention

28. An experimental setup to investigate intermittency in pipe systems Università degli Studi di Genova Corso di Laurea Magistrale in Ingegneria Meccanica Energia & Aeronautica Relatori: Prof. Alessandro Bottaro Prof. R.I. Sujith Candidato: Diego Zangrillo Luglio 2015

29. RQA parameters 28 31/03/2015

30. 29 31/03/2015

31. Multifractal Spectrum: I transition 24/07/2015 30