caa a22 4500 606198202 CHVBK 20210128100933.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s00348-015-1929-3 doi (NATIONALLICENCE)springer-10.1007/s00348-015-1929-3 Experimental analysis of thermo-acoustic instabilities in a generic gas turbine combustor by phase-correlated PIV, chemiluminescence, and laser Raman scattering measurements [Elektronische Daten] [Christoph Arndt, Michael Severin, Claudiu Dem, Michael Stöhr, Adam Steinberg, Wolfgang Meier] A gas turbine model combustor for partially premixed swirl flames was equipped with an optical combustion chamber and operated with CH4 and air at atmospheric pressure. The burner consisted of two concentric nozzles for separately controlled air flows and a ring of holes 12mm upstream of the nozzle exits for fuel injection. The flame described here had a thermal power of 25kW, a global equivalence ratio of 0.7, and exhibited thermo-acoustic instabilities at a frequency of approximately 400Hz. The phase-dependent variations in the flame shape and relative heat release rate were determined by OH* chemiluminescence imaging; the flow velocities by stereoscopic particle image velocimetry (PIV); and the major species concentrations, mixture fraction, and temperature by laser Raman scattering. The PIV measurements showed that the flow field performed a "pumping” mode with varying inflow velocities and extent of the inner recirculation zone, triggered by the pressure variations in the combustion chamber. The flow field oscillations were accompanied by variations in the mixture fraction in the inflow region and at the flame root, which in turn were mainly caused by the variations in the CH4 concentration. The mean phase-dependent changes in the fluxes of CH4 and N2 through cross-sectional planes of the combustion chamber at different heights above the nozzle were estimated by combining the PIV and Raman data. The results revealed a periodic variation in the CH4 flux by more than 150% in relation to the mean value, due to the combined influence of the oscillating flow velocity, density variations, and CH4 concentration. Based on the experimental results, the feedback mechanism of the thermo-acoustic pulsations could be identified as a periodic fluctuation of the equivalence ratio and fuel mass flow together with a convective delay for the transport of fuel from the fuel injector to the flame zone. The combustor and the measured data are well suited for the validation of numerical combustion simulations. Springer-Verlag Berlin Heidelberg, 2015 Arndt Christoph Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut Severin Michael Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut Dem Claudiu Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut Stöhr Michael Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut Steinberg Adam Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, M3H 5T6, Toronto, ON, Canada aut Meier Wolfgang Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut Experiments in Fluids Springer Berlin Heidelberg 56/4(2015-04-01), 1-23 0723-4864 56:4<1 2015 56 348 https://doi.org/10.1007/s00348-015-1929-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00348-015-1929-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Arndt Christoph Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut NATIONALLICENCE 700 1- Severin Michael Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut NATIONALLICENCE 700 1- Dem Claudiu Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut NATIONALLICENCE 700 1- Stöhr Michael Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut NATIONALLICENCE 700 1- Steinberg Adam Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, M3H 5T6, Toronto, ON, Canada aut NATIONALLICENCE 700 1- Meier Wolfgang Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569, Stuttgart, Germany aut NATIONALLICENCE 773 0- Experiments in Fluids Springer Berlin Heidelberg 56/4(2015-04-01), 1-23 0723-4864 56:4<1 2015 56 348