1. Flame, Sound and Feedback
TANGO Progress Meeting
, KTH Stockholm
Flame, Sound and Feedback
Contribution to TANGO Outreach Event
With financial support from Marie Curie Actions

2. Microphone + Amplifier How does this happen?
Acoustic Feedback
Microphone + Amplifier
How does this happen?

3. Acoustic Feedback
How can a flame in a duct
produce noise?
How can resonance
happen in a ducted flame?

4. “Sound is a vibration that propagates as a typically audible
What is sound?
“Sound is a vibration that propagates as a typically audible
mechanical wave of pressure and displacement,
through a medium such as air, and water.”

5. What is sound?

6. Feedback mechanism in a ducted flame
Open end: establishes a feedback system by reflecting the incident wave
Flame: source of pressure disturbance

7. Reflection of a wave at an open end

8. Reflection of a wave at the tube open end

9. Reflection of a wave at an open end

10. What we learnt:
Sound is a pressure wave which propagates in a medium (like air)
Flame can produce pressure disturbances, thus is a source of sound
If the flame is enclosed, a feedback system sets in, because of reflection
In real combustion chambers, with stronger flames, the resonance can be dangerous and can lead to damage of the mechanical components

11. Thanks for your attention!