Modelling and experimental validation of active and passive eddy current sensors for blade tip timing

Jamia, Nidhal; Friswell, Michael I.; El-Borgi, Sami; Rajendran, P.

doi:10.1016/j.sna.2018.10.034

Cited by 14 publications

(6 citation statements)

References 30 publications

(33 reference statements)

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“…Reference [13] proposed a pulsed eddy current signal denoising method, which can remove the noise, but how to accurately extract the pulse rising edge has not resolved. References [14][15][16][17] conducted similar research. However, to date, little research has been done on the measurement error of the BTT technique based on eddy current sensors.…”

Section: Introductionmentioning

confidence: 91%

High-Precision Extraction Method for Blade Tip-Timing Signal with Eddy Current Sensor

Zhang

Ding

Chen

2020

International Journal of Rotating Machinery

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Online monitoring of high-speed rotating blades has always been a hot topic. Of the various methods, the blade tip timing (BTT) technique, based on eddy current sensors, is considered to be the most promising. However, BTT signals are easily influenced by various factors, which means that the accurate extraction of BTT signals remains a challenge. To try to solve this problem, the causes of measurement error were analyzed. The three main reasons for the error were established: the variation in blade tip clearance, the interference of background noise, and the asymmetry of the blade tip shape. Further, pertinent improvement methods were proposed, and a compensation method was proposed for the errors caused by the variation of tip clearance. A new denoising and shaping algorithm based on ensemble empirical mode decomposition (EEMD) was introduced for the errors caused by background noise. Additionally, an optimal installation position of the sensor was also proposed for the errors caused by the asymmetry of the blade tip shape. Finally, simulations and experiments were used to demonstrate the improved methodology. The results show that the measurement error on vibration amplitude and vibration frequency using the proposed method is less than 2.89% and 0.17%, respectively, which is much lower than the traditional method (24.44% and 0.39%, respectively).

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Section: Introductionmentioning

confidence: 91%

High-Precision Extraction Method for Blade Tip-Timing Signal with Eddy Current Sensor

Zhang

Ding

Chen

2020

International Journal of Rotating Machinery

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“…From the point of view of the sensors, in the stationary frame, the BTT samples are acquired once per revolution. The time of arrivals for each sensor in each revolution can be calculated by Equation (5). Then, the response of the system corresponding to the calculated time of arrivals is simply selected from the blade response reflected in the gray curve.…”

Section: Generation Of Sampled Datamentioning

confidence: 99%

“…Its major shortcoming is the under-sampling of the signal related to the rotational speed of the rotating disk under study. The research works on BTT in the last years are about the main areas of the sensor development [4,5], signal processing, vibration parameters identification and the application of this method for condition monitoring [6][7][8]. The present paper is focused on the post-processing of the BTT data to estimate the main vibration parameters even in the case of very close or overlapped resonance peaks.…”

Section: Introductionmentioning

confidence: 99%

Vibration Parameters Estimation by Blade Tip-Timing in Mistuned Bladed Disks in Presence of Close Resonances

2020

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The present paper is focused on the post processing of the data coming from the Blade Tip-Timing (BTT) sensors in the case where two very close peaks are present in the frequency response of the vibrating system. This type of dynamic response with two very close peaks can occur quite often in bladed disks. It is related to the fact that the bladed disk is not perfectly cyclic symmetric and the so called “mistuning” is present. A method based on the fitting of the BTT sensors data by means of a 2 degrees of freedom (2DOF) dynamic model is proposed. Nonlinear least square optimization technique is employed for identification of the vibration characteristics. A numerical test case based on a lump parameter model of a bladed disk assembly is used to simulate different response curves and the corresponding sensors signals. The Frequency Response Function (FRF) constructed at the resonance region is compared with the traditional Sine fitting results, the resonance frequencies and damping values estimated by the fitting procedure are also reported. Accurate predictions are achieved and the results demonstrate the considerable capacity of the 2DOF method to be used as a standalone or as a complement to the standard Sine fitting method.

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“…erefore, accurate measurement of the blade tip timing time is the key of the BTT technology. At present, the optical method [5], the capacitance method [6], the microwave method [7], and the eddy current method [8] can realize the measurements of blade vibration and tip clearance. In the heavily polluted environment, due to the surface pollution of the probe, the measurement accuracy of the optical method decreases.…”

Section: Introductionmentioning

confidence: 99%

An Improved Blade Vibration Parameter Identification Method considering Tip Clearance Variation

Zhang

Wang

2021

Shock and Vibration

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Blade tip timing (BTT) technology is the most effective means for real-time monitoring of blade vibration. Accurately extracting the time of blade tip reaching the sensors is the key to ensure the accuracy of the BTT system. The tip clearance changes due to various complex forces during high-speed rotation. The traditional BTT signal extraction method does not consider the influence of tip clearance change on timing accuracy and introduces large timing errors. To solve this problem, a quadratic curve fitting timing method was proposed. In addition, based on the measurement principle of the eddy current sensors, the relationship among the output voltage of the eddy current sensor, tip clearance, and the blade cutting magnetic line angle was calibrated. A multisensor vibration parameter identification algorithm based on arbitrary angular distribution was introduced. Finally, the experiments were conducted to prove the effectiveness of the proposed method. The results show that in the range of 0.4 to 1.05 mm tip clearance change, the maximum absolute error of the timing values calculated by the proposed method is 26.0359 us, which is much lower than the calculated error of 203.7459 us when using the traditional timing method. When the tip clearance changed, the constant speed synchronous vibration parameters of No. 0 blade were identified. The average value of the vibration amplitude is 1.0881 mm. Compared with the identification results without changing tip clearance, the average value error of the vibration amplitude is 0.0017 mm. It is proved that within the blade tip clearance variation of 0.4 to 0.9 mm, the timing values obtained by the proposed timing method can accurately identify the vibration parameters of the blade.

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Modelling and experimental validation of active and passive eddy current sensors for blade tip timing

Cited by 14 publications

References 30 publications

High-Precision Extraction Method for Blade Tip-Timing Signal with Eddy Current Sensor

High-Precision Extraction Method for Blade Tip-Timing Signal with Eddy Current Sensor

Vibration Parameters Estimation by Blade Tip-Timing in Mistuned Bladed Disks in Presence of Close Resonances

An Improved Blade Vibration Parameter Identification Method considering Tip Clearance Variation

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