Heat release rate of the swirl flames is an important parameter for the gas turbine state. It plays an essential role in the study of combustion characteristics, combustion efficiency and chamber protection. Several swirling CH4/air diffusion flames were investigated in a gas turbine model combustor via the spatial flame mode transition. In the combustion mode transition, we utilized three-dimensional computed tomography of chemiluminescence (3D-CTC) technique due to the complexity of swirling combustion flow field. The 3D emissions of CH∗ were measured and taken as qualitative indicators of the heat release rate under three Reynolds number conditions. This 3D measurement method utilizes 8 multi-directional CH∗ images as inputs combined with tomographic algorithms to compute the 3D distribution of CH∗ intensities. In this study, the transitions of heat release area with Reynolds number were analyzed, and the results show that the heat release rate changing more obviously along the nozzle radial direction than the axis direction, and the largest heat release area moves forward significantly.
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