Session: 04-07 High Hydrogen III

Paper Number: 124845

124845 - Spatial Temperature Measurements in a Swirl-Stabilized Hydrogen-Air Diffusion Flame at Elevated Pressure Using Laser-Induced Grating Spectroscopy 

In this work, Laser-Induced Grating Spectroscopy (LIGS) is used to measure temperatures in a non-premixed swirl-stabilized hydrogen/air flame at 3 bar. Measurements are conducted in the high-pressure, optically-accessible combustor rig at the Cardiff Gas Turbine Research Centre (GTRC) using the Portable In-line LIGS for Optical Thermometry (PILOT) unit (Weller et al. 2023). The PILOT unit is mounted on a motorized two-axis translation stage which enables scalar measurements at different radial and axial positions in the chamber (30 locations in total), including the shear mixing layers and the inner and outer recirculation zones. The oscillation frequency of the collected LIGS signal is proportional to the speed of sound while its shape provides information on the local composition. Thermal and electrostrictive signatures are hence used to map out the temperature field in the combustor. This is the first application of the LIGS technique to non-premixed hydrogen/air flames in a realistic high-pressure gas turbine combustor, which provides relevant datasets for both academic and industrial use.

Preliminary results show a broader range of temperatures across the flame (compared to our previous work on premixed methane/air flames at comparable operating conditions (Weller et al. 2023)) with larger peak temperatures (as high as T = 2500 K). This is evidenced by an increase in the maximum frequencies of the measured LIGS signals which can reach values of the order of 100 MHz. Temperatures are then mapped across the domain to better understand the structure of these non-premixed swirling hydrogen flames. The information can also be used to measure local mixture fractions in the combustor to better understand the complex structure of swirl-stabilized hydrogen/air diffusion flames. The application of LIGS within such a facility opens up the potential for future uses across other industrial applications where spatially-resolved, instantaneous temperature measurements are needed to assess the stability and performances of systems powered by cleaner, carbon-free fuels.

Presenting Author: Oussama Chaib University of Cambridge

Presenting Author Biography: Oussama Chaib is a PhD student at the Hopkinson Laboratory, University of Cambridge, where he is currently undertaking research in experimental combustion under the supervision of Prof. Simone Hochgreb. His research investigates experimentally the behaviour of turbulent premixed hydrogen/air flames subject to thermo-diffusive instabilities.

Authors:

Oussama Chaib University of Cambridge
Lee Weller University of Cambridge
Anthony Giles Cardiff University
Steve Morris Cardiff University
Benjamin A. O. Williams University of Oxford
Simone Hochgreb University of Cambridge