Measurements of 3D temperature field in turbulent flames based on tomographic cesium atomic emission

This work reports an innovative method for three-dimensional (3D) temperature measurements of turbulent flames using tomographic cesium atomic emission. For this effort, the cesium chloride is seeded into the combusting flow, generating bright cesium atomic emission at two transitions (6²_s1/2 → 6²_p3/2,1/2). Ten cameras with bandpass spectral filters (850±20 nm) capture signals from the 6²_s1/2 → 6²_p3/2 transition. Another ten cameras with filters (890±20 nm) capture signals from the 6²_s1/2 → 6²_p1/2 transition. Those images from ten perspectives captured simultaneously from each of the two transitions are used to reconstruct overlapping cesium fields with different Boltzmann fractions and map the 3D temperature field. The technique is validated both numerically using the simulated flame phantom and experimentally on a stable laminar flame. Last, we demonstrate the application of the method in 3D temperature measurements of a turbulent swirl flame. The proposed technique offers great opportunity for spectroscopic temperature measurement in turbulent flames without the requirement of laser excitation or image intensifiers.