Abstract
The spectral characteristics and the structural response of a swirling flowfield are investigated subject to a non-axisymmetric disturbance and a contraction imposed downstream. Two natural frequencies are noted in different regions of the undisturbed swirling flowfield, one is due to a precessing vortex core and the other to the most amplified downstream azimuthal instability. The downstream contraction usually causes compression of the central recirculation zone into two side-lobes, increases the dominant frequencies and forms a straight central vortex core with a high axial velocity. The dominant downstream instability frequency depends linearly on the inlet Reynolds number and on the mode of the breakdown. For the downstream non-axisymmetric disturbance, such as the passing of the turbine blades, the fundamental frequency is not altered by the disturbance and the oscillation strength of the downstream instability is greatly reduced as the excitation frequency remains unmatched with the dominant downstream natural frequency. Downstream azimuthal instability promotes the breakdown recirculation.
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Adrian, R. J.; Yao, C. S. 1987: Power spectra of fluid velocities measured by laser Doppler velocimetry. Exp. Fluids 5, 17–28
Ahmed, S. A.; So, R. M. C. 1987: Characteristics of air jets dischanging normally into a swirling crossflow. AIAA J. 25, 429–435
Altgeld, H.; Jones, W. P.; Wilhelmi, J. 1983: Velocity measurements in a confined swirl driven recirculating flow. Exp. Fluids 1, 73–78
Beér, J. M.; Chigier, N. A. 1983: Combustion aerodynamics. Malabar, FL.: Robert E. Krieger Pub. Co.
Chanaud, R. C. 1965: Observations of oscillatory motion in certain swirling flows. J. F. M., 21, 111–127
Chao, Y. C.: Ho, W. C.; Lin, S. K. 1987: Experiments and computations on coaxial swirling jets with centerbody in an axisymmetric combustor. AIAA-Paper-87-0305
Chao, Y. C. 1988: Recirculation structure of the coannular swirling jets in a combustor. AIAA J. 26, 623–625
Cassidy, J. J.; Falvery, H. T. 1970: Observation of unsteady flow arising after vortex breakdown. J. F. M. 41, 727–736
Escudier, M. P.; Keller, J. J. 1985: Recirculation in swirling flow: a manifestation of vortex breakdown. AIAA J. 23, 111–116
Escudier, M. P.; Merkli, P. 1979: Observation of the oscillatory behavior of a confined ring vortex. AIAA J. 17, No. 3, 253–260
Faler, J. H.; Leibovich, S. 1977: Disrupted states of vortex flow and vortex breakdown. Phys. Fluids 20, 1385–1400
Garg, A. K.; Leibovich, S. 1979: Spectral characteristics of vortex breakdown flowfields. Phys. Fluids 22, 2053–2063
Gouldin, F. C.; Halthore, R. N.; Vu, B. T. 1984: Periodic oscillations observed in swirling flows with and without combustion. Twentieth Symposium on Combustion, The Combustion Institute. 269–276
Gupta, A. K.; Lilley, D. G.; Syred, N. 1984: Swirl Flow, Tunbridge, Wells, England: Abacus Press, 187–198
Heitor, M. V.; Whitelaw, J. H. 1986: Velocity, temperature and species characteristics of the flow in a gas-turbine combustor. Combust. Flame 64, 1–32
Jackson, T. W.; Lilley, D. G. 1984: Accuracy and directional sensitivity of the single-wire technique. AIAA-Paper-84-0367
Jones, W. P.; Wilhelmi, J. 1989: Velocity, temperature and composition measurements in a confined swirl driven recirculating flow. Combust. Sci. and Tech. 63, 13–31
Koutmos, P.; McGuirk, J. J. 1989: Isothermal flow in a gas turbine combustor —a benchmark experimental study. Exp. Fluids 7, 344–354
Lessen, M.; Singh, P. J.; Paillet, F. 1974: The stability of a trailing line vortex Part I. inviscid theory. J. F. M. 63, 753–763
Lilley, D. G.; Abujelala, M. T 1984a: Swirl, confinement and nozzle effect on confined turbulent flow. AIAA-paper-84-1377
Lilley, D. G.; Yoon, H. K. 1984b: Further time-mean measurements in confined swirling flows. AIAA J. 22, 514–515
Lilley, D. G. 1977: Swirl flows in combustion: A review. AIAA, J. 15, 1063–1078
So, R. M. C.; Ahmed, S. A.; Mongia, H. C. 1985: Jet characteristics in confined swirling flow. Exp. Fluids 3, 221–230
Syred, N.; Beér, J. M. 1974: Combustion in swirling flows: A review. Comb. Flame. 23, 143–201
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Chao, Y.C., Leu, J.H., Hung, Y.F. et al. Downstream boundary effects on the spectral characteristics of a swirling flowfield. Experiments in Fluids 10, 341–348 (1991). https://doi.org/10.1007/BF00190250
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DOI: https://doi.org/10.1007/BF00190250