1,- 1TU Wien, Institute of Hydraulic Engineering and Water Resources Management, Wien, Austria (marianne.pons@tuwien.ac.at)
- 2Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
- 3ONERA, The French Aerospace Lab, Department of Aerodynamics, Aeroelasticity and Aeroacoustics (DAAA), Paris-Saclay University, Meudon, 92190, France
Gravity-driven flows are controlled by density contrasts that can be induced, among other factors, by temperature variations. In laboratory experiments, accurately measuring temperature fields is therefore helpful to better understand the mixing mechanisms governing such flows. Optical, non-intrusive techniques are particularly valuable in this context, as they allow spatially and temporally resolved measurements without disturbing the flow.
In this study, we focus on optimizing thermal field imaging obtained using temperature-sensitive lifetime of luminescent materials. The method relies on multi-exposure accumulation within a single frame using a CMOS camera on a custom-built platform that we previously demonstrated to be significantly lower in cost while maintaining precision and sampling rates compared to specialized systems [1]. Measurements can be performed directly in the fluid, using a laser sheet to illuminate dispersed luminescent particles, or at solid boundaries when the sensing materials are coated on the container walls. Despite its proven capabilities, the method has significant optimization potential through independent refinement of both exposure and illumination durations. The main purpose of this investigation is to optimize the technique by minimizing uncertainty. To achieve this, we model uncertainty to predict a theoretically optimized timing scheme and compare it to an empirically optimized scheme. Preliminary results will be presented to assess the correspondence between theoretical and empirical uncertainty minimization, with implications for practical implementation of optimized measurement protocols. The optimized method presented here was developed using YAl3(BO3)4:Cr3+, Y3Al5O12:Cr3+ or ruby but can be applied to different luminescent material with lifetime sensitive to temperature or other quantities (i.e. pH, Oxygen, CO2, etc.).
References:
[1] Rousseau, G., Pons, M., Adelerhof, H., Pellerin, N., Giesbergen, M., Carde, B., Wolf M., Blanckaert K., Borisov S. M., & Fond, B. (2025). Low-cost CMOS-based luminescence lifetime imaging with oxygen, temperature and pH sensors. Sensors and Actuators B: Chemical, 138849, https://doi.org/10.1016/j.snb.2025.138849
How to cite: Pons, M., Rousseau, G., Carde, B., Borisov, S., Fond, B., and Blanckaert, K.: Optimizing a luminescence lifetime measurement technique for non-intrusive temperature imaging in laboratory flows , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9841, https://doi.org/10.5194/egusphere-egu26-9841, 2026.
