KHz-rate volumetric flame imaging using a single camera

Abstract

Abstract Time-resolved three-dimensional diagnostics are experiencing rapid development recently due to the pressing need for the understanding of highly turbulent flows/flames that are usually encountered in next-generation gas-turbine engines or ramjets/scramjets. However, the volumetric measurements typically requires multiple high-speed cameras which are extremely expensive and are only affordable by a few groups in the world. In this work, we aim to develop an endoscopic tomographic system which relies on customized fiber bundles to simultaneously relay nine projections onto a single camera. The system was validated by reconstructing the 3D chemiluminescence distributions of flames produced by a swirl-stabilized burner. The dominant coherent structures of the flames were successfully extracted using dynamic mode decomposition (DMD) which was also adopted to predict the flame evolutions. We found that DMD can faithfully predict a periodically changing flames but the prediction of a non-periodical one is more difficult due to the high nonlinearity of flame dynamics. Although this technique is demonstrated under the context of flame chemiluminescence tomography, it can be easily adapted for other tomographic modalities such as fluorescence tomography used in biomedical imaging to reduce the experimental costs.