A novel method for the identification of flame front’s position on thermoacoustic coupling combustion oscillations

Abstract

Abstract The flame front area is an important parameter to quantify the heat release rate. However, the limitations imposed by the measuring instruments and the measurement methodologies make it difficult to determine the flame front position in an image. This work introduces a method to detect and optimize the flame front boundary. A high‐speed camera was employed to continuously capture the flame images. By setting appropriate intensity thresholds, the impact noise can be eliminated from the image and the flame front boundary can be determined. The binary diagram of the image was morphologically processed to obtain the normalized area fluctuations of the flame front in a temporally resolved manner. Two flame types and combustion regimes were studied. A LABVIEW‐based program was used for the synchronous triggering of the camera, the photomultiplier, and the microphones. The normalized area and photomultiplier output signals of a multiple flame burner obtained within the same period were compared and combined with the spectrum information from the microphone in the cavity. The trend charts were investigated in terms of the Pearson correlation coefficient. The results showed a strong correlation, thereby verifying the feasibility of this method.

Keywords

• combustion oscillations
• flame front recognition
• heat release rate
• high‐speed camera
• impact noise
• normalized area