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# Piezoaeroelastic Energy Harvesting

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Talking @ PASI (Pan-American Advanced Studies Institute) Workshop 2012 - CMS4E, Pontificia Universidad Católica de Chile, January 9-20, 2012, Santiago - Chile

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### Piezoaeroelastic Energy Harvesting

1. 1. PIEZOAEROELASTIC ENERGY HARVESTING Vagner Candido de Sousa – vagner@sc.usp.br Aeronautical Engineering Department Sao Carlos Engineering School University of Sao Paulo – Brazil PASI Workshop 2012Computational Material Science for Energy Generation and Conversion January 9 – 20, Santiago, Chile
2. 2. Outline• Vibration-based energy harvesting• E.H. from aeroelastic vibrations• Piezoelectrically coupled airfoil typical section• Case Studies – Linear model (interaction power - aeroelastic response) – Nonlinear model (broadband generation)• Conclusions
3. 3. Vibration-based energy harvesting• Motivation – Vibrations are available in the environment – Additional (long-term) power source – Reduced power requirement of small devices• Flow-induced energy harvesting – Aeroelastic vibrations – Potential application: UAV• Piezoelectric transduction (direct effect)
4. 4. Airfoil section for energy harvesting2-DOF (Erturk et al., 2010) 3-DOF (Tang and Dowell, 2010) • DOFs: plunge (h), pitch (α) and control surface rotation (β)
5. 5. Piezoaeroelastic equations of motionI   ( I   b(c  a ) S  )   S h  d   k   M     ( I   b(c  a ) S  )  I    S  h  d    k    M      S   S    (m  me )h  d h h  k h h  v p   L     l vpC vp   eq p  h  0  Rl
6. 6. State-space representationI 0 0 0  x   0 I 0 0  x 0 0      K     M 0  x     B D Θs   x   0   0 I 0  x a   E1 E2 F 0  x a  eq    0 0 0   C p  v p   0 Θe 0 1 / Rl   v p   0 I 0 0   M 1K     M 1B  M 1D  M 1Θ s   A  E1 E2 F 0      0 1 / C  Θ eq p e 0 1 / C p  (1 / Rl )  eq   x  Ai x  a i  
7. 7. The experimental system
8. 8. 2-DOF Linear piezoaeroelastic response• Load resistances (Rl): 102, 103, 104, 105 and 106 Ω2-DOF ULF = 12 m/s
9. 9. 2-DOF Linear piezoaeroelastic response
10. 10. The “linear problem”• U∞ < ULF: damped oscillation• U ∞ > ULF: growing amplitudes of oscillation• U ∞ = ULF: the ideal scenario for energy harvesting – U ∞ = ULF is a very particular situation• Nonlinear model – Opportunity for persistent power generation
11. 11. Nonlinear model• Structural nonlinearities can induce subcritical LCOs• The linear torsional spring is replaced by a bilinear spring I   ( I   b(c  a ) S  )   S h  d   k   f fp ( )  M        k  fp    fp  f fp ( )   0  fp     fp  k     fp   fp2-DOF with bilinear spring 3-DOF with bilinear spring Sousa et al., 2011, Smart Mat. Struc. 3-DOF: Power with airspeed (70% ~ 98% ULF)
12. 12. Summary and conclusions• Piezoaeroelastically coupled typical section for energy harvesting• Harvests energy from linear and nonlinear aeroelastic vibrations• Nonlinear aeroelastic phenomena can provide persistent power generation in a wide range of airflow velocities
13. 13. Thank you! Questions?• The author gratefully acknowledge – PASI 2012 CMS4E organizing committee – CNPq