Output characteristics of two-circle coaxial optical fiber bundle with regard to three-dimensional tip clearance

Xie, Suchao; Zhang, Xiaodong; Wu, Bi-Ru; Xiong, Yiwei

doi:10.1364/oe.26.025244

Cited by 10 publications

(5 citation statements)

References 12 publications

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“…They are both based on two independents receiving fibre rings that are located at different radii surrounding the central transmitting fibre. They were designed based on the mathematical approach shown in References [37,38] but including the design constraints (maximum allowed diameter for the cross-section of the fibre bundle, expected tip clearance working range, etc.) imposed by the turbine specifications in order to have the most sensitive performance in their respective linear regions (Figure 4).…”

Section: Methodsmentioning

confidence: 99%

“…To avoid this, a source light with a stable power is needed. There is also a more complex variant, based on the Gaussian dispersion of the power of the traveling beam, where various fibre groups at different radial distances are needed to measure how the beam intensity is radially distributed [15,29,34,35,36,37,38]. This technology has more tolerance to the target angle compared to the intensity-based technique, but the sensor is more expensive and complex to build.…”

Section: Introductionmentioning

confidence: 99%

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Performance Comparison of Three Fibre-Based Reflective Optical Sensors for Aero Engine Monitorization

Fernández-Bello

Amorebieta

Beloki

et al. 2019

Sensors

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Among the different available optical technologies, fibre bundle-based reflective optical sensors represent an interesting alternative for parameter monitorization in aero engines. Tip clearance is one of the parameters of great concern for engine designers and engineers. In the framework of this optical technology, three fibre-based reflective optical sensors have been compared. Two of them are custom designed and based on the same geometrical fibre arrangement, whereas the third one is commercially available and relies on a different geometrical arrangement of the fibres. Their performance has been compared in clearance measurements carried out during an experimental program followed at a transonic wind tunnel for aero turbines. The custom-designed solution that operates in the most sensitive part of its response curve proved to be by far the most reliable tool for clearance measurements. Its high resolution opens up the possibility to detect small blade features such as cracks, reflectivity changes, etc. that otherwise could not be tracked. These results show that the detection of unexpected features on blade tips may have an important effect on how the clearance is calculated, ultimately giving rise to corrective actions.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance Comparison of Three Fibre-Based Reflective Optical Sensors for Aero Engine Monitorization

Fernández-Bello

Amorebieta

Beloki

et al. 2019

Sensors

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“…When the crack faults occur, the blades appear complex dynamic behaviors resulting in the change of three-dimension parameters. Hence, in the paper, the threedimension parameters are simply called three-dimensional blade tip-clearance [22], abbreviated to 3-DBTC. In fact, the 3-DBTC refers to three geometric parameters (i.e., radial direction, axial direction, and circumferential direction.)…”

Section: Intelligent Diagnosis Approach For the Crack Fault Of Turbine Blades Using 3-dbtc Signals A Description Of 3-dbtc Signalsmentioning

confidence: 99%

“…However, considering the blades usually show three-dimensional vibration behaviors under various working loads, the two methods mentioned above are difficult to reflect the complex dynamical behaviors of blades. Thus, a new non-contact measurement technique has been studied in recent years, called three-dimensional blade tip clearance (3-DBTC) [22]- [26], which are essentially multi-dimensional vibration signals. Teng et al [25] studied the change regulation of 3-DBTC under several typical types of loads by simulation experiments and proved that 3-DBTC is effective, offering a theoretical foreshadow to monitor conditions feasible.…”

Section: Introductionmentioning

confidence: 99%

A Novel Intelligent Fault Diagnosis Approach for Early Cracks of Turbine Blades via Improved Deep Belief Network Using Three-Dimensional Blade Tip Clearance

et al. 2021

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Aero-turbines usually work in various non-stationary and harsh operating environments. Its blades easily appear early crack faults in long-time operation, and it is difficult to dig out discriminant features of early crack. To solve these problems, in the paper, a novel intelligent approach for early crack diagnosis of turbine blades using three-dimensional blade tip clearance is presented. In order to improve feature learning ability to obtain better generalization ability, the paper firstly develops a novel deep learning method based on deep belief networks (DBNs). Considering the fact that the feature degradation easily occurs in deeper layers because of the change of the distribution in each layer's outputs with the increase of the layers, it is hard to decide which layer to learn features is useful for fault diagnosis. Accordingly, in the pre-training process, the global back-reconstruction (GBR) mechanism is introduced into DBNs to optimize the feature learning ability. The GBR mechanism can be realized between the input layer and hidden layers by ''shortcut connection'', and the layer to learn more discriminant features can be determined automatically without prior knowledge. Moreover, due to three-dimensional blade tip clearance (3-DBTC) acquired from three different directions of turbine blades contains much more useful crack failure multiscale information, it is suitable to be used as an input from which to extract multiscale discriminant features. Eventually, in the supervised training, the softmax regression model is employed to classify the health conditions of turbine blades using these sensitive features learned from 3-DBTC. The experimental results show that the proposed method can effectively identify the crack of turbine blades with fairly high diagnostic accuracies and significantly outperform other methods considered in the paper.INDEX TERMS Turbine blade, three-dimensional blade tip clearance, deep belief networks, feature extraction, fault diagnosis.

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“…To overcome the deficiencies that the BTT signal and the conventional BTC cannot fully reflect the fault information of blade cracks, Teng et al proposed the three-dimensional blade tip clearance (3D-BTC), which contains comprehensive crack fault information in three dimensions [19]. Moreover, in order to realize the fault diagnosis of blade cracks based on the 3D-BTC, an optical fiber sensor with three sensing units was designed to monitor the 3D-BTC [20]. Besides, the 3D-BTC demodulation method was proposed, and a dynamic measurement system was established so that the 3D-BTC could be accurately measured [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics Analysis of 3D Blade Tip Clearance for Turbine Blades with Typical Cracks

Zhang

Xiong

Huang

et al. 2022

International Journal of Aerospace Engineering

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As well known, the crack is a typical fault of turbine blades, which is difficult to detect due to the weak fault features contained in the rotor vibration. Although some fault diagnosis methods based on blade tip timing (BTT) are proposed to detect blade cracks, the limited fault features can be extracted because the BTT signals contain only one-dimensional fault information. Based on the dynamic analysis, the cracked blade undergoes three-dimensional (3D) deformation so that it would be reflected in the changes of the three-dimensional blade tip clearance (3D-BTC). Therefore, the dynamic characteristics of the 3D-BTC of turbine blades with typical cracks should be investigated to obtain its change rule and achieve a more comprehensive diagnosis of blade cracks. In this paper, the 3D finite element model of the turbine blisk is established, and the fluid-thermal-solid coupling analysis is implemented to calculate the blade deformation. Then, a novel dynamic computation method is proposed to calculate the 3D-BTC based on the blade deformation. The typical blade cracks are taken into consideration, and the dynamic characteristics of the 3D-BTC regarding the typical cracks are analyzed to obtain its change rule. The results show that abundant crack fault information can be obtained based on the 3D-BTC, which can facilitate the comprehensive diagnosis of turbine blade cracks.

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Output characteristics of two-circle coaxial optical fiber bundle with regard to three-dimensional tip clearance

Cited by 10 publications

References 12 publications

Performance Comparison of Three Fibre-Based Reflective Optical Sensors for Aero Engine Monitorization

Performance Comparison of Three Fibre-Based Reflective Optical Sensors for Aero Engine Monitorization

A Novel Intelligent Fault Diagnosis Approach for Early Cracks of Turbine Blades via Improved Deep Belief Network Using Three-Dimensional Blade Tip Clearance

Dynamic Characteristics Analysis of 3D Blade Tip Clearance for Turbine Blades with Typical Cracks

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