The full three-dimensional viscous numerical simulation is employed to analyze and compare the interaction phenomena of the unsteady flow field at two axial clearances in an axial-flow turbine stage and then the mechanism of the unsteady loss fluctuation is adopted to describe the reason of entropy fluctuation. The results indicate that when the axial clearance is doubled
the potential interaction changes significantly at the entire stator and the leading edge of the rotor
and the fluctuation amplitude of wall static pressure decreases by about 80% and 60%
respectively. The descending of the potential interaction strength is much faster than that of the negative jet. When the negative jet arrives at the trailing edge of the rotor suction side
the repression effect on the flow separation will occur
resulting in a new triggering mechanism of the calming effect. In addition
the coupling relation between static pressure and entropy in the boundary layer flow of the stator suction side is built by a dissipation function
and a method to analyze the loss fluctuation in the unsteady flow field is developed.
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references
GAETANI P, PERSICO G, OSNAGHI C, et al. Investigation of the flow field in a high-pressure turbine stage for two stator-rotor axial gaps, part I: three-dimensional time-averaged flow field [J]. ASME Journal of Turbomachinery, 2007, 129(3): 572-579.
KEN-ICHI F, KAZUTOYO Y, MAMORU K, et al. Experimental studies on aerodynamic performance and unsteady flow behaviors of a single turbine stage with variable rotor-stator axial gap: comparisons with time-accurate numerical simulation [C/CD]∥Proceedings of the ASME Turbo Expo 2007. New York, USA: ASME, 2007: GT2007-27670.
SCHENNACH O, WOISETSCHIAGER J, FUCHS A, et al. Experimental investigations of clocking in a one-and-a-half-stage transonic turbine using laser Doppler velocimetry and a fast response aerodynamic pressure probe [J]. ASME Journal of Turbomachinery, 2007, 129(2): 372-381.
URBASSIK R M, WOLFF J M. Unsteady aerodynamics and interactions between a high pressure turbine vane and rotor [J]. ASME Journal of Turbomachinery, 2006, 128(1): 35-42.
YAMADA K, FUNAZAKI K, HIROMA K, et al. Effect of wake passing on unsteady aerodynamic performance in a turbine stage [C/CD]∥Proceedings of ASME Turbo Expo 2006. New York, USA: ASME, 2006: GT2006-90783.
HODSON H, DAWES W N. On the interpretation of measured profile losses in unsteady wake-turbine blade interaction studies [J]. ASME Journal of Turbomachinery, 1998, 120(2): 276-284.
陈海生. 叶轮机械内部流动研究进展[J]. 机械工程学报, 2007, 43(2): 2-12.
CHEN Haisheng. Review of investigation into internal flow of turbomachinery [J]. Chinese Journal of Mechanical Engineering, 2007, 43(2): 2-12.
UZOL O, ZHANG X F. Investigation of unsteady wake-separated boundary layer interaction using particle-image-velocimetry [C/CD]∥Proceedings of ASME Turbo Expo 2007. New York, USA: ASME, 2007: GT2007-28099.
ARNONE A, MARCONCINI M, GRECO A S D. Numerical investigation of three-dimensional clocking effects in a low pressure turbine [C/CD]∥Proceedings of ASME Turbo Expo 2003. New York, USA: ASME, 2003: GT2003-38414.
DENTON J D. Loss mechanisms in turbomachines [J]. ASME Journal of Turbomachinery, 1993, 115(4): 621-656.
YAO J X, CARSON S. Hpt/lpt interaction and flow management in the inter-turbine space of a modern axial flow turbine [C/CD]∥Proceedings of ASME Turbo Expo 2006. New York, USA: ASME, 2006: GT2006-90636.