%0 Journal Article %1 Stöhr20092925 %A Stöhr, M. %A Sadanandan, R. %A Meier, W. %D 2009 %J Proceedings of the Combustion Institute %K Stöhr experimental flame structures study unsteady %N 2 %P 2925 - 2932 %R 10.1016/j.proci.2008.05.086 %T Experimental study of unsteady flame structures of an oscillating swirl flame in a gas turbine model combustor %U http://www.sciencedirect.com/science/article/pii/S1540748908003593 %V 32 %X Velocity fields and flame structures of a partially premixed swirl flame in a gas turbine model combustor are measured in axial and transverse sections using simultaneous (Stereo-)PIV and OH-PLIF. The flame, operated under atmospheric pressure with air and methane at a thermal power of 10.3 kW and a global equivalence ratio of ϕ = 0.75, features thermoacoustic oscillations at a frequency f ≈ 295 Hz. The averaged flow field with inner and outer recirculation zones is typical of swirl-stabilized flames, and the instantaneous measurements show the presence of a helical vortex (PVC) located in the inner shear layer. The PVC, which rotates with a different frequency than the thermoacoustic oscillation, leads to an enhanced mixing of burned and unburned gas and thus to stabilization of the flame. Two distinct large-scale structures of velocity and OH are found in the transverse cross-sections. The first type is characterized by a roughly annular region of inflowing unburned gas and distinct inner and outer recirculation zones. In the second type, the region of positive axial velocity forms a spiral, and the recirculation zone consists of an inner region that is connected to the outer parts by a narrow curved zone along the spiral arm. Whereas the first type is a typical scenario of vortex breakdown with a PVC, the transient spiral recirculation zone observed here has, to our knowledge, not yet been reported. A phase-resolved analysis shows that the annular form correlates with low, and the spiral form with high rates of global heat release.

@article{Stöhr20092925, abstract = {Velocity fields and flame structures of a partially premixed swirl flame in a gas turbine model combustor are measured in axial and transverse sections using simultaneous (Stereo-)PIV and OH-PLIF. The flame, operated under atmospheric pressure with air and methane at a thermal power of 10.3 kW and a global equivalence ratio of ϕ = 0.75, features thermoacoustic oscillations at a frequency f ≈ 295 Hz. The averaged flow field with inner and outer recirculation zones is typical of swirl-stabilized flames, and the instantaneous measurements show the presence of a helical vortex (PVC) located in the inner shear layer. The PVC, which rotates with a different frequency than the thermoacoustic oscillation, leads to an enhanced mixing of burned and unburned gas and thus to stabilization of the flame. Two distinct large-scale structures of velocity and OH are found in the transverse cross-sections. The first type is characterized by a roughly annular region of inflowing unburned gas and distinct inner and outer recirculation zones. In the second type, the region of positive axial velocity forms a spiral, and the recirculation zone consists of an inner region that is connected to the outer parts by a narrow curved zone along the spiral arm. Whereas the first type is a typical scenario of vortex breakdown with a PVC, the transient spiral recirculation zone observed here has, to our knowledge, not yet been reported. A phase-resolved analysis shows that the annular form correlates with low, and the spiral form with high rates of global heat release.}, added-at = {2012-09-14T13:13:51.000+0200}, author = {Stöhr, M. and Sadanandan, R. and Meier, W.}, biburl = {https://www.bibsonomy.org/bibtex/2883a97ac3c78d4ec0c5dc380813e9451/adisaurabh}, description = {ScienceDirect.com - Proceedings of the Combustion Institute - Experimental study of unsteady flame structures of an oscillating swirl flame in a gas turbine model combustor}, doi = {10.1016/j.proci.2008.05.086}, interhash = {7d5f1f6c146f953dec1f3b2e2d0e8d65}, intrahash = {883a97ac3c78d4ec0c5dc380813e9451}, issn = {1540-7489}, journal = {Proceedings of the Combustion Institute}, keywords = {Stöhr experimental flame structures study unsteady}, number = 2, pages = {2925 - 2932}, timestamp = {2012-09-14T13:13:51.000+0200}, title = {Experimental study of unsteady flame structures of an oscillating swirl flame in a gas turbine model combustor}, url = {http://www.sciencedirect.com/science/article/pii/S1540748908003593}, volume = 32, year = 2009 }