Speaker
Description
The improvement of technical systems in the field of aerospace engineering and energy process engineering requires fundamental experimental work and the respective diagnostics tools for measuring the local variables temperature, concentration and velocities. These quantities determine the efficiency and pollutant emissions and consequently, at least planar measurements must be available with the highest possible spatial and temporal resolution. Optical measurement techniques are ideal for recording several parameters simultaneously.
Current imaging techniques are based on laser-induced fluorescence (LIF) or laser-induced phosphorescence (LIP), which are being further developed especially for studying complex reactive flows. This contribution will give an overview of the capability of Tracer-LIF for measuring the temperature distribution as well as concentration fields in mixing processes. This technique is utilized to study liquid fuel injection and spray processes, e.g. to characterize mixture temperature and fuel vapor concentrations. Experiments under very harsh supercritical conditions will be presented, which are prevailing in rocket combustors or IC engines. Furthermore, the LIF technique is also capable to measure droplet temperatures in a 2-colour approach, and it can be applied for planar droplet sizing when combined with Laser-Mie-scattering to determine the SMD (Sauter Mean Diameter).
With LIP, inert particles are used in a similar way instead of gas tracers, with which the local temperature of the gas phase can be resolved in addition to the velocity distribution (using Particle Image Velocimetry, PIV). This novel method can be used for low and high temperature applications (even above 1000 K) and it is also applicable for surface thermometry, e.g. for measuring wall temperatures in combustors. This measurement technique is already utilized to some extent in combustion systems, e.g. for improving the film cooling of walls in gas turbines combustors, but it can also be transferred to a wide range of high-temperature applications in process engineering, such as chemical reactors.
References
[1] Zigan, L.: Imaging Techniques for Multi-Parameter Determination in Mixture Formation and Combustion Processes. Habilitation Thesis, FAU Erlangen-Nürnberg, 2020
urn:nbn:de:bvb:29-opus4-148447
[2] Abram, C., Straußwald, M., Sander, T., Zigan, L., Pfitzner, M.: Applications of Thermographic Particle Image Velocimetry to Film Cooling Flow Experiments in a Closed Loop Wind Tunnel. 20th LISBON Laser Symposium 2022, Lisbon, Portugal, 11 - 14 July 2022
[3] Koegl, M., Mishra, Y.N., Baderschneider, K., Conrad, C., Lehnert, B., Will, S., Zigan, L.: Planar droplet sizing for studying the influence of ethanol admixture on the spray structure of gasoline sprays. Experiments in Fluids (2020) 61:209
[4] Lind, S., Retzer, U., Will, S., Zigan, L.: Investigation of mixture formation in a diesel spray by tracer-based laser-induced fluorescence using 1-methylnaphthalene. Proceedings of the Combustion Institute 36, 4497–4504, 2017
| Keywords | Laser Diagnostics, Imaging, thermometry, concentration, Fluorescence, Phosphorescence |
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