Laser-Optical Blade Tip Clearance Measurement System

Barranger, J. P.; Ford, Maureen

doi:10.1115/1.3230742

Cited by 22 publications

(13 citation statements)

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“…There is extensive published material available on tip clearance measurement systems that can measure clearance over every blade in a compressor or turbine stage. The most commonly used technique is optical triangulation, as Drinkuth et al [11], White [12], Baker et al [13], Barranger and Ford [14], and Ford [15] describe. Optical clearance measurement systems work reliably in a manufacturing environment [16,17].…”

Section: Introductionmentioning

confidence: 99%

Blade by Blade Tip Clearance Measurement

Sheard¹

2011

International Journal of Rotating Machinery

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This paper describes a capacitance-based tip clearance measurement system which engineers have used in the most demanding turbine test applications. The capacitance probe has survived extended use in a major European gas turbine manufacturer's hightemperature demonstrator unit, where it functioned reliably at a turbine entry temperature in excess of 1800 degrees Kelvin. This paper explores blade by blade tip clearance measurement techniques and examines probe performance under laboratory conditions in support of high-temperature installations. The paper outlines the blade by blade tip clearance measurement technique and describes the experimental facility used to study tip clearance measurement. The paper also fully describes the method used to calibrate the measurement system in order to ascertain measurement accuracy. The paper clarifies how the practical problems were overcome associated with making blade by blade tip clearance measurements in both compressor and turbine environments. Since its initial development, gas turbine development programmes have routinely used the clearance measurement system. The inherent robustness of the system has resulted in reliable in-service measurement of clearance in real world applications.

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Section: Introductionmentioning

confidence: 99%

Blade by Blade Tip Clearance Measurement

Sheard¹

2011

International Journal of Rotating Machinery

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“…There are instances where there is a need to measure radius over every blade around a disc and in these cases the SMP of Davidson et al is not suitable. Optical triangulation systems, such as that described by Barranger & Ford [1980], use a laser to measure clearance over individual blades. These systems are large and inherently fragile and therefore are not ideal for use in the tip grinding process.…”

Section: Radius Over Every Bladementioning

confidence: 99%

A High Speed Capacitance Based System for Gauging Turbomachinery Blading Radius During the Tip Grind Process

Sheard

Westerman

Killeen

et al. 1992

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

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During the manufacture and overhaul of gas turbines it is necessary to ensure that all blades in a stage are of an equal and known length to minimise the loss in performance that arises as a consequence of the clearance between rotor tip and engine casing. Modern compressor and turbine blades are generally loose fitting in their root fixings and only adopt their true working position when running. In this paper, a new technique for measuring the rotor radius over individual blades is described. The measurement technique utilises a capacitance based clearance measurement system which enables rotor radius to be measured over each blade while spinning fast enough to ensure that the blades are centrifugally loaded into their true working position. The measurement technique is described, as is the system utilised to calibrate and reduce output into engineering units. The mechanical design of the “measurement head” is presented and the CNC lathe to which it interfaces described. Finally, the results of an experimental programme, utilising a fully bladed compressor disc undertaken to ascertain system performance, are presented.

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“…triangulation 1 , multiwavelength interferometry 15 , holography 16 , optical coherence tomography (OCT) 9 and time-of-flight measurements 6 overcome this drawback. However, at most optical techniques the measurement rate is limited either by the speed of mechanical scanning (time-domain OCT) or by the detector frame rate and minimum exposure time (triangulation, frequency-domain OCT).…”

Section: Introductionmentioning

confidence: 99%

Laser Doppler distance sensors using phase and frequency evaluation

et al. 2009

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The optical inspection and metrology for non-optics industry gains increasing importance. Several optical sensors are available for shape measurements of rough surfaces. However, at fast rotating objects such as turbine blades high temporal resolution is necessary, which often can not be fulfilled by commercially available sensors. The recently developed laser Doppler distance sensors allow temporal resolutions in the microsecond range. The independence of the distance measurement uncertainty to the lateral surface velocity is unique. The laser Doppler distance sensors were realized by the evaluation of the interference signal frequency as well as the interference signal phase. Both sensors have been employed for high-speed inspection.Keywords: non-incremental interferometric technique, system calibration and measurement uncertainty analysis, realtime insitu process control, shape measurement of rough surfaces, tip clearance and vibration measurements of turbo machines

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Laser-Optical Blade Tip Clearance Measurement System

Cited by 22 publications

References 0 publications

Blade by Blade Tip Clearance Measurement

Blade by Blade Tip Clearance Measurement

A High Speed Capacitance Based System for Gauging Turbomachinery Blading Radius During the Tip Grind Process

Laser Doppler distance sensors using phase and frequency evaluation

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