1. 6th TANGO Project Meeting (Ansaldo Energia, Genoa) 14 September 2015
Aswathy Surendran (ESR)
Advisor: Prof. Maria A. Heckl
Keele University, UK

2. Contents
Research Task
Recap
Work done
On-going & Future work
Outlook

3. Research Task
Task 3.3 : Analytical study of idealised combustion system with heat exchanger

4. Recap Tube row modelling Cavity backed tube row : No flow
T and R coefficients
Parametric study
Cavity backed tube row : No flow
No Structural Loss
Structural Loss

5. Recap Slit-plate backed by cavity : With flow Increasing Mach number
First mode
Surendran and Heckl (ICSV22)

6. Work done
Tube row backed by cavity : With flow
Ongoing

7. Work done
Complete system
Open end

8. Work done
Complete system
n – τ law

9. Work done
Complete system
Assuming that ∆𝑥→0
Transfer Function

10. Work done Secondment at Bekaert Gain – Phase plots Uin 340 K 1500 K
𝐻𝑇𝐹= 𝑄 ′ / 𝑄 𝑜 𝑢 / 𝑈 𝑖𝑛

11. Work done Transfer Function Approximations Constrained Least Squares
Piecewise Continuous
Gain Phase
Ongoing

12. Work done
Complete system
TF Approx.

13. Work done
Complete system
Assuming that ∆𝑥→0
Quasi-Steady

14. Work done Quasi-Steady Analysis Compressible Quasi-Steady
M1 and Point of separation
1+ 𝑀 2 𝑝 − 𝑀 1 𝑝 1 − = 𝑇 + 𝑅 − 𝑅 + 𝑇 − 𝑀 1 𝑝 − 𝑀 2 𝑝 2 −

15. Analytical estimation
Work done
Quasi-Steady Analysis
Compressible Quasi-Steady
M1 and Point of separation
1+ 𝑀 2 𝑝 − 𝑀 1 𝑝 1 − = 𝑇 + 𝑅 − 𝑅 + 𝑇 − 𝑀 1 𝑝 − 𝑀 2 𝑝 2 −
Ongoing
Analytical estimation

16. Work done Secondment at Bekaert
Centreline velocity Separation Location

17. Work done
Complete system
Quasi-Steady

18. Work done
Complete system
Closed end

19. Increasing Mach number
Work done
Complete system
Stability maps
First mode
Increasing Mach number

20. On-going & Future work On-going Future Work Flow separation point
Approximations to TF
Gain and Phase
Complete system
Validity of assumptions
Future Work
Secondment at KTH
Experiments for T± and R±

21. Thank You ! Outlook Experimental/Numerical study on the same
Including the effects of other loss mechanism
Structural loss
Thank You !

22. Tube row: Structural losslc
Reff
σs = 0.5
ωres of Rijke tube ~ [ ] s-1

23. Tube row: Structural loss
Coinciding frequencies
Appropriate tube row (radius)
Appropriate damping

24. Slit-plate with bias flow
Slit-plate with flow
Slit-plate with bias flow
𝑇= 𝜌 𝑜 𝜔 𝑉 / 𝑘𝑑
𝑅=1− 𝜌 𝑜 𝜔 𝑉 / 𝑘𝑑
𝜌 𝑜 𝜔 𝑉 𝑘𝑑 = 𝑓(𝜔,𝑑,𝑠, 𝑐 𝑜 ,𝑈)†
Perturbation volume flux through the slit
Accounts for influence of vortex shedding
Sound energy Unsteady vortices
† Dowling, A. P. and Hughes, I. J. (1992), Sound absorption by a screen with a regular array of slits, Journal of Sound and Vibration, Vol. 156 (3), 387–405.

25. Quasi-Steady Analysis
Hofmans (1998)†
𝑆𝑟= 𝑓 ℎ 𝑑 𝑢 𝑑 , 𝐻𝑒= 𝑓 ℎ 𝑝 𝑐 𝑜
Incompressible model
Sr ≪ 1, He ≪ 1, M1 ≪ 1
Compressible model
Sr ≪ 1, He ≪ 1, M1 – finite,
Mj ~ 𝒪(1)
† Hofmans, G. C. J., Vortex Sound in Confined Flows, Technische Universiteit Eindhoven, PhD Thesis, (1998).

26. Quasi-Steady Analysis
Our Model
Incompressible Quasi-Steady
𝑝 𝑝 1 − = 𝑇 + 𝑅 − 𝑅 + 𝑇 − 𝑝 𝑝 2 −

27. Work done Secondment at Bekaert ANSYS Fluent Geometry – , ,
Inlet velocity – 0.1 , 0.2 , 0.5 m/s
Tube diameter – 3 , 5 mm
Open-area ratio – 0.1 , 0.2

28. Source & Sink
COMSOL