Noninterference blade-vibration measurement system for gas turbine engines

The blade vibration measurement is crucial for gas turbine engines in order to ensure safe operations. One of the techniques is blade tip-timing (BTT), which is under the assumption that rotor speed is constant and depends on a once-per-revolution (OPR) timing reference to calculate the blade tip displacement, and identifying the blade sequence. However, this assumption is incorrect for transient conditions, and the installation of OPR sensor sometimes is not allowable and reliable. These reasons greatly limit the application of BTT technique. This paper proposes a self-correcting (SC) BTT method to realize the blade vibration measurement under different operating conditions without using the OPR sensor, which is based on the polynomial fitting and a reference probe is used to correct high-order fitting coefficients. Numerical results show that the SC-BTT method can greatly reduce the fitting error caused by blade pitch and vibrational parameters. Experimental results demonstrate that the proposed technique is capable of removing the limitation of the lack of OPR sensor and overcoming the drawbacks of OPR system, such as the failure of OPR sensor or low-speed resolution. For three investigated cases, the relative errors of derived rotor speed are below 0.12%. The relative error of blade peak-to-peak amplitude (PPA) and the initial phase angle are around 3% at the resonance region with engine order (EO) 2.

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Microwave Blade Tip Clearance Measurement System

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; General ◽

10.1115/96-gt-002 ◽

1996 ◽

Cited By ~ 3

Author(s):

Richard Grzybowski ◽

George Foyt ◽

Hartwig Knoell ◽

William Atkinson ◽

Josef Wenger

Keyword(s):

Gas Turbine ◽

Measurement System ◽

Ceramic Materials ◽

Tip Clearance ◽

Turbine Engines ◽

Gas Turbine Engines ◽

Phase Measurements ◽

Blade Tip ◽

Clearance Control ◽

Blade Tip Clearance

This paper describes the development of a Microwave Tip Clearance Measurement System for use in the gas turbine environment Applications for this sensor include basic tip clearance measurements, seal wear measurement and active blade tip clearance control in gas turbine engines. The system being developed was designed for useful operation to temperatures exceeding 1093°F, since only ceramic materials are directly exposed in the gas path. Other advantages of this microwave approach to blade tip clearance sensing include the existence of an inherent self-calibration in the sensor that permits accurate operation despite temperature variations and possible abrasion by the rotating blades. Earlier experiments designed to simulate this abrasion of the sensor head indicated that rubs as deep as 1 mm (40 mils) were easily tolerated. In addition, unlike methods based upon phase measurements, this method is very insensitive to cable vibration and length variations. Finally, this microwave technique is expected to be insensitive to fuel and other engine contamination, since it is based on the measurement of resonant frequencies, which are only slightly affected by moderate values of loss due to contamination.

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Laser-Optical Blade Tip Clearance Measurement System

Journal of Engineering for Power ◽

10.1115/1.3230742 ◽

1981 ◽

Vol 103 (2) ◽

pp. 457-460 ◽

Cited By ~ 13

Author(s):

J. P. Barranger ◽

M. J. Ford

Keyword(s):

Gas Turbine ◽

Measurement System ◽

Optical Measurement ◽

Tip Clearance ◽

Turbine Engines ◽

Gas Turbine Engines ◽

Turbine Engine ◽

Blade Tip ◽

Graphic Terminal ◽

Blade Tip Clearance

The need for blade tip clearance instrumentation has been intensified recently by advances in technology of gas turbine engines. A new laser-optical measurement system has been developed to measure single blade tip clearances and average blade tip clearances between a rotor and its gas path seal in rotating component rigs and complete engines. The system is applicable to fan, compressor and turbine blade tipe clearance measurements. The engine mounted probe is particularly suitable for operation in the extreme turbine environment. The measurement system consists of an optical subsystem, an electronic subsystem and a computing and graphic terminal. Bench tests and environmental tests were conducted to confirm operation at temperatures, pressures, and vibration levels typically encountered in an operating gas turbine engine.

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