Abstract

We propose an all-fiber, self-calibrating, economical probe that is capable of near-real-time, single-port, simultaneous blade-to-blade tip-clearance measurements with submillimeter accuracy (typically <100 µm, absolute) in the first stages of a gas turbine. Our probe relies on the interference between backreflected light from the blade tips during the 1µs blade passage time and a frequency-shifted reference with variable time delay, making use of a low-coherence light source. A single optical fiber of arbitrary length connects the self-contained optics and electronics to the turbine.

© 2003 Optical Society of America

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References

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  1. C. Sieverding, Tip-Clearance Effects in Axial Turbomachines, Lecture series 1985–5 (Von Karman Institute, Rhode-St-Genese, Belgium, 1989).
  2. A. Steiner, Meas. Sci. Technol. 11, 865 (2000).
    [CrossRef]
  3. A. G. Sheard, S. G. O'Donnell, and F. F. Stringfellow, J. Eng. Gas Turbines Power 121, 167 (1999).
    [CrossRef]
  4. H. S. Dhadwal and A. P. Kurkov, J. Turbomach. 121, 481 (1999).
    [CrossRef]
  5. J. P. Barranger and M. J. Ford, J. Eng. Power 103, 457 (1981).
    [CrossRef]

2000

A. Steiner, Meas. Sci. Technol. 11, 865 (2000).
[CrossRef]

1999

A. G. Sheard, S. G. O'Donnell, and F. F. Stringfellow, J. Eng. Gas Turbines Power 121, 167 (1999).
[CrossRef]

H. S. Dhadwal and A. P. Kurkov, J. Turbomach. 121, 481 (1999).
[CrossRef]

1989

C. Sieverding, Tip-Clearance Effects in Axial Turbomachines, Lecture series 1985–5 (Von Karman Institute, Rhode-St-Genese, Belgium, 1989).

1981

J. P. Barranger and M. J. Ford, J. Eng. Power 103, 457 (1981).
[CrossRef]

Barranger, J. P.

J. P. Barranger and M. J. Ford, J. Eng. Power 103, 457 (1981).
[CrossRef]

Dhadwal, H. S.

H. S. Dhadwal and A. P. Kurkov, J. Turbomach. 121, 481 (1999).
[CrossRef]

Ford, M. J.

J. P. Barranger and M. J. Ford, J. Eng. Power 103, 457 (1981).
[CrossRef]

Kurkov, A. P.

H. S. Dhadwal and A. P. Kurkov, J. Turbomach. 121, 481 (1999).
[CrossRef]

O'Donnell, S. G.

A. G. Sheard, S. G. O'Donnell, and F. F. Stringfellow, J. Eng. Gas Turbines Power 121, 167 (1999).
[CrossRef]

Sheard, A. G.

A. G. Sheard, S. G. O'Donnell, and F. F. Stringfellow, J. Eng. Gas Turbines Power 121, 167 (1999).
[CrossRef]

Sieverding, C.

C. Sieverding, Tip-Clearance Effects in Axial Turbomachines, Lecture series 1985–5 (Von Karman Institute, Rhode-St-Genese, Belgium, 1989).

Steiner, A.

A. Steiner, Meas. Sci. Technol. 11, 865 (2000).
[CrossRef]

Stringfellow, F. F.

A. G. Sheard, S. G. O'Donnell, and F. F. Stringfellow, J. Eng. Gas Turbines Power 121, 167 (1999).
[CrossRef]

J. Eng. Gas Turbines Power

A. G. Sheard, S. G. O'Donnell, and F. F. Stringfellow, J. Eng. Gas Turbines Power 121, 167 (1999).
[CrossRef]

J. Eng. Power

J. P. Barranger and M. J. Ford, J. Eng. Power 103, 457 (1981).
[CrossRef]

J. Turbomach.

H. S. Dhadwal and A. P. Kurkov, J. Turbomach. 121, 481 (1999).
[CrossRef]

Meas. Sci. Technol.

A. Steiner, Meas. Sci. Technol. 11, 865 (2000).
[CrossRef]

Other

C. Sieverding, Tip-Clearance Effects in Axial Turbomachines, Lecture series 1985–5 (Von Karman Institute, Rhode-St-Genese, Belgium, 1989).

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Figures (3)

Fig. 1
Fig. 1

Experimental setup of the low-coherence interferometer. All components, except for the circulator, are connected by single-mode fiber and angled fiber-optical–physical-contact connectors. The circulator uses polarization-maintaining fiber. PC, personal computer.

Fig. 2
Fig. 2

Terminology for reflections from collimator lens surfaces and blade tip. Rays 2 and 3 are Fresnel reflections of the incident light off the surfaces of the collimator lens. Ray 1 is the diffuse reflection from the passing blade tip.

Fig. 3
Fig. 3

Power spectrum intensity at 55 MHz versus optical delay for a simulated tip clearance of D=4.8 mm. The labels indicate the origin of the peaks according to Fig. 2 (also see text). The subscripts refer to the interferometer arm.

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