The role of tip leakage vortex breakdown in compressor rotor aerodynamics
- Kyushu Univ. Fukuoka (Japan). Dept. of Mechanical Science and Engineering
The breakdown of tip leakage vortex has been investigated on low-speed axial compressor rotor with moderate blade loadings. Effects of the breakdown on the rotor aerodynamics are elucidated by Navier-Stokes flow simulations and visualization techniques for identifying the breakdown. The simulations show that the leakage vortex breakdown occurs inside the rotor at a lower flow rate than the peak pressure rise operating condition. The breakdown is characterized by the existence of the stagnation point followed by a bubblelike recirculation region. The onset of breakdown causes significant changes in the nature of the tip leakage vortex: large expansion of the vortex and disappearance of the streamwise vorticity concentrated in the vortex. The expansion has an extremely large blockage effect extending upstream of the leading edge. The disappearance of the concentrated vorticity results in no rolling-up of the vortex downstream of the rotor and the disappearance of the pressure through on the casing. The leakage flow field downstream of the rotor is dominated by the outward radial flow, resulting from the contraction of the bubblelike structure of the breakdown region. It is found that the leakage vortex breakdown plays a major role in characteristic of rotor performance at near-stall conditions. As the flow rate is decreased from the peak pressure rise operating condition, the breakdown region grows rapidly in the streamwise, spanwise, and pitchwise directions. The growth of the breakdown causes the blockage and the loss to increase drastically. Then, the interaction of the breakdown region with the blade suction surface gives rise to the tree-dimensional separation of the suction surface boundary layer, thus leading to a sudden drop in the total pressure rise across the rotor.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 679288
- Report Number(s):
- CONF-980615-; ISSN 0889-504X; TRN: IM9940%%108
- Journal Information:
- Journal of Turbomachinery, Vol. 121, Issue 3; Conference: American Society of Mechanical Engineers (ASME) turbo expo `98 - land, sea, air, Stockholm (Sweden), 2-5 Jun 1998; Other Information: PBD: Jul 1999
- Country of Publication:
- United States
- Language:
- English
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