Thermo-acoustics and its detection in a premixed flame

TL;DR

This paper introduces a novel optical method to detect thermo-acoustic disturbances in premixed flames, enabling detailed analysis of flame propagation and acoustic interactions in combustion processes.

Contribution

A new optical technique based on light-matter interaction is developed to detect thermo-acoustic disturbances in premixed flames, distinguishing acoustic waves from flame fronts.

Findings

Thermo-acoustic signals are successfully detected and distinguished from flame fronts.

Acoustic waves interact with the flame at various locations and times.

The technique provides insights into flame dynamics and acoustic interactions.

Abstract

A new optical technique based on light-matter interaction is devised in-house to detect thermo-acoustic disturbances generated after ignition and during propagation of a premixed flame front in a half open channel. The technique involves passing a polarized laser light through a medium whose density or refractive index varies due to the passage of acoustic waves and/or flame front and then capturing the leaked depolarised light through an analyser by a photo-detector. The technique is applied to combustor involving premixed flame propagation and tulip inversion. The thermo-acoustic signals and the flame front are distinguished by comparing the oscilloscope signal with high speed photography of the flow-field. Acoustic waves are found to intercept the flame propagation at various axial locations and time instants.