Microwave Blade Tip Clearance Measurements: Principles, Current Practices and Future Opportunities

2012 ◽  
Author(s):  
Alexander Maslovskiy ◽  
Mikhail Bakulin ◽  
Maksim Snitko
Keyword(s):  
Laboratory Tests ◽  
Combustion Products ◽  
Tip Clearance ◽  
Turbine Engines ◽  
Microwave Measurement ◽  
Gas Turbine Engines ◽  
Measurement Systems ◽  
Microwave Sensor ◽  
Blade Tip ◽  
Blade Tip Clearance

This article is devoted to the principles of construction of the microwave tip clearance measurement system in gas turbine engines and describes a microwave sensor that designed to operate in temperatures up to 1700C with a resolution of 0.05 mm. The sensor can effectively operate in dirty environments and has the ability to see through oil, combustion products, and other common contaminants. Also the article is devoted to the use of microwave measurement systems to solve other practical problems (measurements tip-timing, vibration, pressure and etc). The main applications of these systems are discussed on the basis of the plant tests and laboratory tests of aircraft turbine engines.

scholarly journals Microwave Blade Tip Clearance Measurement System

1996 ◽  
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.

scholarly journals A review of blade tip clearance–measuring technologies for gas turbine engines

2020 ◽  
Vol 53 (3-4) ◽  
pp. 339-357 ◽  
Author(s):  
Bing Yu ◽  
Hongwei Ke ◽  
Enyu Shen ◽  
Tianhong Zhang
Keyword(s):  
Gas Turbine ◽  
Measuring Method ◽  
Gas Turbine Engine ◽  
Tip Clearance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Turbine Engine ◽  
Blade Tip ◽  
Safety And Stability ◽  
Blade Tip Clearance

Blade tip clearance is one of the important parameters affecting the performance, safety and stability of a gas turbine engine. However, it is difficult to measure the tip clearance in real time and accurately during the development and test process of an engine. In order to promote the development of tip clearance–measuring technology and the optimal design of the gas turbine engine, some typical measuring methods of tip clearance and a novel measuring method based on AC discharge are introduced. In this article, the significance for measuring tip clearance of an engine is illustrated first. Then, operating principles, characteristics and developments of those typical measurement approaches are introduced. After that, these methods are analyzed, and the particular characteristic of each measuring approach is summarized.

scholarly journals Laser-Optical Blade Tip Clearance Measurement System

1981 ◽  
Vol 103 (2) ◽  
pp. 457-460 ◽  
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.

scholarly journals New Sensors and Techniques for the Structural Health Monitoring of Propulsion Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Mark Woike ◽  
Ali Abdul-Aziz ◽  
Nikunj Oza ◽  
Bryan Matthews
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Crack Detection ◽  
Rotating Disk ◽  
Tip Clearance ◽  
Turbine Engines ◽  
Structural Health ◽  
Major Interest ◽  
Blade Tip ◽  
Blade Tip Clearance

The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA), through the Aviation Safety Program (AVSP), has taken a lead role in the development of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. This paper presents a summary of key results and findings obtained from three different structural health monitoring approaches that have been investigated. This includes evaluating the performance of a novel microwave blade tip clearance sensor; a vibration based crack detection technique using an externally mounted capacitive blade tip clearance sensor; and lastly the results of using data driven anomaly detection algorithms for detecting cracks in a rotating disk.

Blade Tip Clearance Measurement Systems for High Speed Turbomachinery Applications and the Potential for Blade Tip Timing Applications

2020 ◽  
Author(s):  
Jack David Stubbs ◽  
Muhammad Arslan Shahid
Keyword(s):  
Measurement Uncertainty ◽  
High Speed ◽  
Radial Displacement ◽  
Measurement Techniques ◽  
Test System ◽  
Tip Clearance ◽  
Optical Systems ◽  
Measurement Systems ◽  
Blade Tip ◽  
Blade Tip Clearance

Abstract As turbomachinery OEMs focus efforts to further increase reliability, power and efficiencies, the running clearance between blade tips and stator continue to be of the utmost importance. This paper investigates the capability of capacitive tip clearance systems to perform individual blade tip clearance measurements on high speed rotors of up to 90,000rpm. A rotor was designed using finite element analysis; unique blade responses have been predicted. The objective of this investigation was to consider two different approaches to the application of blade tip clearance measurements and the system requirements to accurately measure low levels of radial displacement of a target rotating between 1,000rpm and 90,000rpm. The first uses the standard approach with passive probes and the second, a new technique using active probes that have demonstrated bandwidths of 1.2MHz and increased measuring range with a lower level of measurement uncertainty. Both systems’ approaches are compared, and their capabilities are evaluated for high-speed applications. The higher bandwidth capabilities of the latter system, combined with smaller sensor diameters, produces comparable signal rise times to the optical systems used in blade tip timing measurements. The difference in approach offers the potential of contamination resistant sensors for long term blade tip timing applications and measurement probes that do not require cooling systems to withstand higher temperature applications. The use of different probe configurations, in a number of applications, has demonstrated a two-fold improvement in the measurement range whilst producing lower levels of noise and uncertainty when applied to blade targets made from composites, aluminium and nickel-alloy materials. The measurement data presented includes individual blade’s radial displacement, identified shaft axial displacement, effects of resonance in the test system and the identification of the main drivers of measurement uncertainty along with an achievable value. The capacitive measurement systems’ performance for blade tip clearance is analysed and reported. The capability to perform other measurement techniques such as blade tip timing with a dual use measurement probe is also analysed and reported. This is done by correlating measurement results between the capacitive systems with that of a repeat measurement of the same target using an optical BTT system.

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