Session: 04-30 Hydrogen III

Submission Number: 176151

Inverse Reconstruction of Temperature in a Turbulent Hydrogen Flame From Two-Color Radiation Measurements 

Two-color radiation thermography is regularly used to infer the gas temperature within the reacting flow field of a combustor. It is a non-intrusive line-of-sight measurement technique that offers measurements across the entire optical accessible region. The experimental setup can be implemented with relative ease, making it a highly efficient diagnostic method, particularly when testing time is costly and space around the test section is limited. The main challenge, however, lies in the deconvolution of the line-of-sight radiation signal, which is required to recover local temperatures within the flow field. While this has been achieved successfully for laminar flames, realistic burner configurations are characterized by highly turbulent and stratified flow fields. These fluctuations, along with the nonlinear dependence of radiation on temperature, lead to significant discrepancies in the reconstructed mean temperatures when state-of-the-art deconvolution techniques are applied

To improve the accuracy of two-color radiation thermography measurements in turbulent flames, this study employs a stochastic flow model that mimics the turbulent fluctuations. An optimization algorithm suggests statistical parameters for the flow model, which creates an extensive series of estimated intensity fields. The corresponding virtual line-of-sight signals are then compared with radiation measurements from a high-speed infrared camera in two spectral ranges. This inverse process is iterated until the discrepancy between the virtual and the experimental line-of-sight data is minimal.

This paper presents an experimental validation using a turbulent hydrogen multi-regime burner. The reconstructed mean temperatures are compared to recently published 1D-Raman-Rayleigh measurements for identical operation conditions, showing a satisfactory agreement. In addition, the stochastic flow model provides information on temperature fluctuations and integral length scales, thereby offering valuable additional insights into the characteristics of the turbulent flow field.

Presenting Author: Thomas Soworka German Aerospace Center (DLR), Institute of Propulsion Technology, Combustor Department

Presenting Author Biography: Thomas studied mechanical engineering at the Karlsruhe Institute of Technology (KIT) in Germany. After graduating in 2013, he joined Alstom Power in Switzerland as a Combustion Test Engineer. Since 2016, he has been working at the German Aerospace Center (DLR) in Cologne, where he conducts research in the combustor department of the Institute of Propulsion Technology. His work focuses on experimental test campaigns, and he has developed a stochastic flame model to improve the accuracy and significance of line-of-sight measurements in turbulent flames.

Authors:

Thomas Soworka German Aerospace Center (DLR), Institute of Propulsion Technology, Combustor Department
Thomas Behrendt German Aerospace Center (DLR), Institute of Propulsion Technology, Combustor Department
Shuguo Shi Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics
Justin Knubel Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics
Robin Schultheis Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics
Bertram Janus German Aerospace Center (DLR), Institute of Propulsion Technology, Combustor Department
Andreas Dreizler Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics