1. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 Combustor test rig composed, from left to right, of a rear air injection unit, two identical injection stages, and a square cross-section chamber. Microphones are mounted at different points of the apparatus. Figure Legend:

2. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 Schematic view of the experimental facility with feeding lines. Propane and air are injected through two opposite inlets in two successive stages. The supplying lines are equipped with IMDs (see Fig. ) to characterize their impedance at different locations. Figure Legend:

3. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 IMD used to measure the acoustic reflection coefficient along the feeding lines Figure Legend:

4. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 Instantaneous power spectral density measured at different locations in the combustion chamber and along the feeding lines during one run for Φ=0.75 and α=15% Figure Legend:

5. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 Reflection coefficient of the air/fuel feeding lines at the flow controller outlet compared with the same quantities calculated at the premixer inlets. Measurements are carried out on the fly on the combustion test rig. Figure Legend:

6. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 The air mass flow controller is mounted on the ITHACA impedance test bench. Air flow and acoustic level correspond to the ones encountered in the combustor. Figure Legend:

7. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 Comparison between reflection coefficients measured at the exit of the flow controller during a hot fire test and on the ITHACA test bench. Top to bottom: air from stage 1, fuel from stage 1, and fuel from stage 2. Figure Legend:

8. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 Coherence between the microphones A and C in the IMD during on the fly measurement Figure Legend:

9. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 Locations of the acoustic reflection coefficient measurements on the combustion test rig Figure Legend:

10. Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: A Methodology for On the Fly Acoustic Characterization of the Feeding Line Impedances in a Turbulent Swirled Combustor J. Eng. Gas Turbines Power. 2010;133(1):011504-011504-7. doi:10.1115/1.4001987 The measured and reconstructed acoustic reflection coefficients of the first stage air feeding line at the premixer inlet Figure Legend: