scholarly journals An optical fiber Blade Tip Clearance Sensor for Active Clearance Control Applications

2011 ◽  
Vol 15 ◽  
pp. 984-988 ◽  
Author(s):  
Jia Binghui ◽  
Zhang Xiaodong
Keyword(s):  
Optical Fiber ◽  
Tip Clearance ◽  
Control Applications ◽  
Blade Tip ◽  
Clearance Control ◽  
Blade Tip Clearance

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 An Optical Fiber Measurement System for Blade Tip Clearance of Engine

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Jia Binghui ◽  
He Lei
Keyword(s):  
Optical Fiber ◽  
Measurement System ◽  
High Speed ◽  
Dynamic Performance ◽  
Measurement Range ◽  
Tip Clearance ◽  
Processing Unit ◽  
Blade Tip ◽  
Optical Fiber Measurement ◽  
Blade Tip Clearance

The benefits of reducing the tip clearance have been receiving many scholars’ attention all the time, which bring turbine efficiency increasing, emissions reduction, payloads increasing, and mission range abilities extension. In order to gain the blade tip clearance dynamically, a prototype optical fiber measurement system was built and tested based on the rotor test rig. The optical fiber tip clearance measurement system consists of the reflective intensity-modulated optical fiber bundle (sensor), main signal processing unit, high-speed data acquisition card, and a computer. The static performance and dynamic performance experiments were conducted to verify the performance of the system we designed. In addition, the results show that the accuracy of the system is 25 μm or better; the stability of the measurement system was evaluated in room temperature. The clearance measurement range is about 5 mm, and sensitivity of the sensor is 0.0733/mm. Furthermore, the typical tip clearance dynamic measurement experiment results show that the system has good dynamic response characteristics as well. The system will provide a new tool for engine health monitoring or fast active tip clearance control.

Investigation on the Turbine Blade Tip Clearance Measurement and Active Clearance Control Based on Eddy Current Pulse-Trigger Method

2017 ◽  
Author(s):  
Weimin Wang ◽  
Huajin Shao ◽  
Xing Shao ◽  
Kailiang Song
Keyword(s):  
Experimental Study ◽  
Control System ◽  
Eddy Current ◽  
Axial Displacement ◽  
Tip Clearance ◽  
Current Sensor ◽  
Non Linear ◽  
Blade Tip ◽  
Clearance Control ◽  
Blade Tip Clearance

Blade tip clearance (BTC) measurement and active clearance control (ACC) have been and continue to be a fundamental concern in turbomachinery, which are closely bound up with the efficiency and reliability. This paper addresses the BTC measurement and ACC experimental study based on eddy current pulse-trigger method (ECPTM). And the implementation of ACC by axial displacement of the blisk is novel and this paper is the first to present the technique. The purpose of this paper is three fold. The first portion of this paper addresses the BTC measurement in different rotating speeds based on the larger scale rig, where a high-bandwidth (100 kHz) eddy current sensor (HECS) is employed. The results show that the relative errors of BTC values are not much bigger than 20%. The result indicates that ECPTM is more generally applicable in the condition where the eddy current sensor (ECS) is insufficient sampling caused by the limit of narrow bandwidth, especially under the high linear velocity condition. The second portion of this paper describes the ACC system where an electro-hydraulic proportional position control system (EHPPCS) is employed as the actuator. EHPPCS has the advantages of small size, fast response, resistance to load stiffness, large output and simple operation, which is widely applicable to the automatic control system of industrial power. This system optimizes the geometry shapes of casing and the blade tips to create a linear relationship of BTC values related to the axial displacement of the rotor. The BTC values can be transferred into axial displacement of the rotor, and then a voltage/current-BTC values characteristic can be obtained by employing EHPPCS in different rotating speeds. Unfortunately, one of the core components of EHPPCS is an overflow valve with a non-linear and time-variable voltage/current-pressure characteristic. Besides, the pressure-axial displacement characteristic of tilting pad thrust bearing is also non-linear. All those non-linear characteristics make it unsatisfactory to use the conventional PID control algorithm to achieve effective control of the system, which cause many difficulties in controlling of axial displacement of the rotor. So the last portion of this paper is the experimental study on ACC based on the above system by adopting sliding mode adaptive control of nonlinear system (SMACNS). The BTC values have been obtained under different outlet pressures by changing the current in different rotating speeds. The results indicate that this approach has nice robustness and smooth controlled quantity, and can overcome the difficulty caused by nonlinearity, parameter uncertainty and load disturbance. And then, the precision verification and error analysis are made. However, this work is a proof-of-concept demonstration using a laboratory setup providing the basis for BTC active control and blade health monitoring (BHM) based on ECS.

Investigation on tip clearance control for the high-pressure rotor of an uncooled vaneless counter-rotating turbine

2020 ◽  
pp. 095441002095050
Author(s):  
Wei Zhao ◽  
Xiuming Sui ◽  
Kai Zhang ◽  
Zeming Wei ◽  
Qingjun Zhao
Keyword(s):  
High Pressure ◽  
Leading Edge ◽  
Back Pressure ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Trailing Edge ◽  
Blade Tip ◽  
Cooling Air ◽  
Clearance Control ◽  
Blade Tip Clearance

In order to develop a tip clearance control system for an uncooled vaneless counter-rotating turbine, tip clearance variation of its high pressure rotor blade at off-design conditions is analyzed. Aero-thermal interaction simulation is performed to predict the temperature and deformation of the solid blade. At operating conditions with rotating speeds greater than 60% design value and expansion ratios greater than 85% design value, the blade tip clearance height at leading edge remains unchanged when the expansion ratio decreases, meanwhile that at trailing edge decreased obviously. However, the tip clearance height variations at the leading edge and trailing edge are almost the same in a conventional subsonic turbine at such conditions. The cause is that the flow in the high-pressure rotor is choked at these conditions. The choked flow results in that the fluid and solid blade temperatures upstream of the throat are not affected by the back pressure and only those downstream of the throat increases with the back pressure. Consequently, the blade height at leading edge keeps constant, and that at trailing edge varies because of thermal expansion. To avoid the rubbing of the blade and case, the blade height at trailing edge is diminished by 30%. As a result, the blade tip clearance height at low speed operating conditions increases in axial direction. Such a design leads to a stronger tip leakage flow. More flow losses might be generated. Therefore, a casing cooling method is proposed to control the blade tip clearance height at leading edge and trailing edge respectively. The deformations of the casing with different mass flow rate of cooling air at design and off-design conditions are calculated. It shows that the blade tip clearance heights at leading edge and at trailing edge of the rotor can be well controlled with appropriate amount of cooling air.

scholarly journals Test Rig for Evaluating Active Turbine Blade Tip Clearance Control Concepts

2005 ◽  
Vol 21 (3) ◽  
pp. 552-563 ◽  
Author(s):  
Scott B. Lattime ◽  
Bruce M. Steinetz ◽  
Malcolm G. Robbie
Keyword(s):  
Turbine Blade ◽  
Tip Clearance ◽  
Test Rig ◽  
Blade Tip ◽  
Clearance Control ◽  
Blade Tip Clearance

Turbine-blade tip clearance and tip timing measurements using an optical fiber bundle sensor

2013 ◽  
Author(s):  
Iker Garcia ◽  
Josu Beloki ◽  
Joseba Zubia ◽  
Gaizka Durana ◽  
Gotzon Aldabaldetreku
Keyword(s):  
Optical Fiber ◽  
Turbine Blade ◽  
Fiber Bundle ◽  
Tip Clearance ◽  
Blade Tip ◽  
Optical Fiber Bundle ◽  
Blade Tip Clearance

Optical fiber measurement system for 3-D variation of turbine blade tip clearance

2018 ◽  
Vol 26 (7) ◽  
pp. 1578-1587 ◽  
Author(s):  
张小栋 ZHANG Xiao-dong ◽  
吴 冰 WU Bing ◽  
谢思莹 XIE Si-ying
Keyword(s):  
Optical Fiber ◽  
Turbine Blade ◽  
Measurement System ◽  
Tip Clearance ◽  
Blade Tip ◽  
Optical Fiber Measurement ◽  
Blade Tip Clearance
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