Effects of nonaxisymmetric tip clearance on axial compressor performance and stability
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Gas Turbine Lab.
- GE Aircraft Engines, Cincinnati, OH (United States). Aero Technology Labs.
The effects of circumferentially nonuniform tip clearance on axial compressor performance and stability have been investigated experimentally and analytically. A theoretical model for compressor behavior with nonaxisymmetric tip clearance has been developed and used to design a series of first-of-a-kind experiments on a four-stage, low-speed compressor. The experiments and computational results together show clearly the central physical features and controlling parameters of compressor response to nonaxisymmetric tip clearance. It was found that the loss in stall margin was more severe than that estimated based on average clearance. The stall point was, in fact, closer to that obtained with uniform clearance at the maximum clearance level. The circumferential length scale of the tip clearance (and accompanying flow asymmetry) was an important factor in determining the stall margin reduction. For the same average clearance, the loss in peak pressure rise was 50 percent higher for an asymmetry with fundamental wavelength equal to the compressor circumference than with wavelength equal to one-half the circumference. The clearance asymmetry had much less of an effect on peak efficiency; the measured maximum efficiency decrease obtained was less than 0.4 percent compared to the 8 percent decrease in peak pressure rise due to the asymmetric clearance. The efficiency penalty due to nonaxisymmetric tip clearance was thus close to that obtained with a uniform clearance at the circumferentially averaged level. The theoretical model accurately captured the decreases in both steady-state pressure rise and stable operating range which are associated with clearance asymmetry.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 316080
- Report Number(s):
- CONF-970604-; ISSN 0889-504X; TRN: IM9908%%160
- Journal Information:
- Journal of Turbomachinery, Vol. 120, Issue 4; Conference: 42. international gas turbine and aeroengine congress and exhibition, Orlando, FL (United States), 2-5 Jun 1997; Other Information: PBD: Oct 1998
- Country of Publication:
- United States
- Language:
- English
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