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.

中文翻译：

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一种识别热声耦合燃烧振荡上火焰锋面位置的新方法

火焰前沿面积是量化放热率的重要参数。然而，测量仪器和测量方法所施加的限制使得很难确定图像中的火焰前沿位置。这项工作介绍了一种检测和优化火焰前沿边界的方法。采用高速摄像机连续捕捉火焰图像。通过设置适当的强度阈值，可以从图像中消除撞击噪声并确定火焰前沿边界。对图像的二进制图进行形态学处理，以时间分辨的方式获得火焰前沿的归一化面积波动。研究了两种火焰类型和燃烧方式。基于 LABVIEW 的程序用于同步触发相机、光电倍增管、和麦克风。将同一时间段内得到的多火焰燃烧器的归一化面积和光电倍增管输出信号与腔内传声器的光谱信息进行比较和组合。根据 Pearson 相关系数研究趋势图。结果显示出很强的相关性，从而验证了该方法的可行性。