Proper Orthogonal Decomposition for Experimental Investigation of Flame Instabilities

摘要

An experimental investigation of premixed flames undergoing thermoacoustic instability is presented. The paper focuses on the data postprocessing, aiming at extracting information about the dynamics that are lost through the classical time-averaging approach. Proper orthogonal decomposition together with a derived a posteriori phase-averaging procedure are applied to OH* chemiluminescence data, obtained with a simple experimental setup at a low acquisition rate. The combustion dynamics are successfully reconstructed from the raw data, without the need of extra acquisitions or of phase locking the measurements, and providing extra information about the instability modes. The method was validated against high-speed-camera direct-light measurements. In an intermittent case close to bifurcation, the procedure further helps to sort out different states of the flame.