Three-dimensional temperature field measurement in high-temperature gas flows through phosphorescent spectral light field imaging

Accurate three-dimensional (3D) temperature measurement in high-temperature gas flows with restricted optical access is essential for understanding the coupled heat and mass transfer mechanism and optimizing high-performance thermal systems. This work develops a single-viewpoint instantaneous volumetric thermometry technique based on phosphorescent spectral light field imaging (SLFI). First, a geometric-optics-based SLFI forward model specifically tailored to sparsely distributed phosphorescent tracer particles is established. Subsequently, an enhanced dual-band reconstruction algorithm is proposed to reconstruct the volumetric emission intensity fields by enforcing inter-band physical consistency, enabling accurate 3D temperature reconstruction based on voxel-wise phosphorescence intensity ratios. Following a numerical evaluation of the proposed method, a SLFI-based 3D temperature measurement system is built and experimentally validated in the turbulent shear layer downstream of a turbine vane cascade. Numerical simulations demonstrate reconstruction quality factors exceeding 0.92 and maximum relative temperature errors below 1.52% over the temperature range of 300–800 K at particle concentrations ranging from 0.2 to 0.8 particles per micro-lens (ppm). Experimental results show that the developed SLFI-based 3D temperature measurement system achieves a mean relative error of 1.58% under operating conditions of 373–773 K compared to a thermocouple measurement at a reference point. These results confirm the accuracy and robustness of the proposed technique for volumetric thermometry in high-temperature gas flows.