scholarly journals Synchronous Vibration Parameters Identification of Variable Rotating Speed Blades Based on New Improved Two-Parameter Method without OPR Sensor

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Liang Zhang ◽  
Huiqun Yuan ◽  
Xin Li
Keyword(s):  
Parameter Identification ◽  
Initial Phase ◽  
Parameters Identification ◽  
Identification Accuracy ◽  
Parameter Method ◽  
Vibration Parameter ◽  
Rotating Speed ◽  
Blade Tip ◽  
Vibration Parameters ◽  
Two Parameter

Blade tip-timing is one of the most effective methods for blade vibration parameters identification of turbomachinery. Once-per revolution (OPR) sensor is usually used to determine the rotating speed and as a time reference. However, the OPR sensor leads to a large measurement error or even failure, or it is difficult to install. A new improved two-parameter method without the OPR sensor is proposed to identify the synchronous vibration parameters of variable rotating speed blades. Three eddy current sensors are required to identify the excitation order, vibration amplitude, resonance rotating speed frequency, resonance frequency, and the initial phase of the blades. Numerical simulation of blade synchronous vibration parameters identification is presented, and the identification error of the method is investigated. The simulation results show that the identification accuracy of this method is better than that of the traditional two-parameter method and the improved method in reference, especially in the identification of the vibration initial phase. Experiments are conducted based on the blade tip-timing vibration measurement system. The results indicate that the standard errors of vibration parameter identification results between the new method and the method in reference are smaller, except for the initial phase. It is consistent with the results of the simulation identification. The synchronous vibration parameter identification of variable rotating speed blades without the OPR sensor is achieved based on the new improved two-parameter method.

scholarly journals An Improved Blade Vibration Parameter Identification Method considering Tip Clearance Variation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Liang Zhang ◽  
Qidi Wang ◽  
Xin Li
Keyword(s):  
Parameter Identification ◽  
Eddy Current ◽  
Vibration Amplitude ◽  
Tip Clearance ◽  
Vibration Parameter ◽  
Blade Vibration ◽  
Average Value ◽  
Blade Tip ◽  
Vibration Parameters ◽  
Clearance Change

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.

New Step to Improve the Accuracy of Blade Synchronous Vibration Parameters Identification Based on Combination of GARIV and LM Algorithm

2017 ◽  
Author(s):  
Weimin Wang ◽  
Sanqun Ren ◽  
Shan Huang ◽  
Qihang Li ◽  
Kang Chen
Keyword(s):  
Experimental Study ◽  
Parameters Identification ◽  
Least Square ◽  
Experimental Result ◽  
Blade Vibration ◽  
Vibration Displacement ◽  
Campbell Diagram ◽  
Identification Method ◽  
Blade Tip ◽  
Vibration Parameters

Generally, turbine blade vibration can be divided into asynchronous vibration and synchronous vibration. Comparing to parameters identification of asynchronous vibration, that of the synchronous vibration is more difficult and needs more sensors. The applicability of the synchronous identification method is more stringent than that of asynchronous identification method. A new method is presented to identify the blade synchronous vibration parameters based on the blade tip-timing (BTT) method and previous achievements in this region. Here, the parameters, such as the frequency of harmonic resonance center, blade vibration amplitude and the initial phase, are obtained by the nonlinear least square fitting algorithm based on relationships between the rotation speed and the blade tip displacement. We call this way as sweep frequency fitting (SFF) method. As the blade is operated at a constant speed that is near the frequency of resonance center, the blade vibration displacement can be obtained by the sensors at different positions, so the blade synchronous vibration Engine Order (EO) can be obtained by the global autoregressive with instrumental variables (GARIV) method. Furthermore the Campbell diagram of blade synchronous vibration can be plotted by the parameters obtained by GARIV method and SFF method. In the experimental study, the parameter identification of blade synchronous vibration is completed and the Campbell diagram of blade vibration is accurately plotted under the excitation of six magnets. Meanwhile, the experimental study and analysis on the harmonic vibration of blade with different numbers of excitation are carried out. The relative deviation of the dynamic frequency of blade between the experimental result and simulation result is less than 1%.

scholarly journals Research on Blade Synchronous Vibration Parameter Identification Using Blade Tip Timing without the once per Revolution Sensor

2019 ◽  
Vol 55 (13) ◽  
pp. 64
Author(s):  
ZHOU Changyi ◽  
HU Haifeng ◽  
YANG Yongmin ◽  
GUAN Fengjiao ◽  
XU Hailong
Keyword(s):  
Parameter Identification ◽  
Vibration Parameter ◽  
Blade Tip

scholarly journals A novel none once per revolution blade tip timing based blade vibration parameters identification method

2020 ◽  
Vol 33 (7) ◽  
pp. 1953-1968 ◽  
Author(s):  
Weimin WANG ◽  
Xulong ZHANG ◽  
Dongfang HU ◽  
Dengpeng ZHANG ◽  
Paul ALLAIRE
Keyword(s):  
Parameters Identification ◽  
Blade Vibration ◽  
Identification Method ◽  
Blade Tip ◽  
Vibration Parameters

scholarly journals Comparative Analysis of Identification Methods for Mechanical Dynamics of Large-Scale Wind Turbine

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3429 ◽  
Author(s):  
Chu ◽  
Yuan ◽  
Hu ◽  
Pan ◽  
Pan
Keyword(s):  
Mutual Information ◽  
Parameter Identification ◽  
Wind Turbines ◽  
Closed Loop ◽  
Control Design ◽  
Identification Accuracy ◽  
Mass Model ◽  
Identification Methods ◽  
Advanced Control ◽  
Mechanical Dynamics

With increasing size and flexibility of modern grid-connected wind turbines, advanced control algorithms are urgently needed, especially for multi-degree-of-freedom control of blade pitches and sizable rotor. However, complex dynamics of wind turbines are difficult to be modeled in a simplified state-space form for advanced control design considering stability. In this paper, grey-box parameter identification of critical mechanical models is systematically studied without excitation experiment, and applicabilities of different methods are compared from views of control design. Firstly, through mechanism analysis, the Hammerstein structure is adopted for mechanical-side modeling of wind turbines. Under closed-loop control across the whole wind speed range, structural identifiability of the drive-train model is analyzed in qualitation. Then, mutual information calculation among identified variables is used to quantitatively reveal the relationship between identification accuracy and variables’ relevance. Then, the methods such as subspace identification, recursive least square identification and optimal identification are compared for a two-mass model and tower model. At last, through the high-fidelity simulation demo of a 2 MW wind turbine in the GH Bladed software, multivariable datasets are produced for studying. The results show that the Hammerstein structure is effective for simplify the modeling process where closed-loop identification of a two-mass model without excitation experiment is feasible. Meanwhile, it is found that variables’ relevance has obvious influence on identification accuracy where mutual information is a good indicator. Higher mutual information often yields better accuracy. Additionally, three identification methods have diverse performance levels, showing their application potentials for different control design algorithms. In contrast, grey-box optimal parameter identification is the most promising for advanced control design considering stability, although its simplified representation of complex mechanical dynamics needs additional dynamic compensation which will be studied in future.

Investigation of Fan Blades Vibration due to Blade/Casing Rubbing Interactions Using In-Plane Two-Dimensional Model

2018 ◽  
Author(s):  
Jiaguangyi Xiao ◽  
Yong Chen ◽  
Hua Ouyang ◽  
Anjenq Wang
Keyword(s):  
Travelling Waves ◽  
Golden Section ◽  
Contact Forces ◽  
Two Dimensional ◽  
Rotating Speed ◽  
Bladed Disk ◽  
Speed Range ◽  
Blade Vibrations ◽  
Blade Tip ◽  
External Forces

Interactions between casings and bladed-disks of modern turbofan engines may occur through various mechanisms: casing distortions, rotor vibrations and casing vibrations to name a few. These interactions might lead to nonlinear blade vibrations, which could then induce severe damages to both structures. The impacts of casing vibrations on the vibration behaviors of engine blades are studied in this paper. A two-dimensional in-plane model is established in this paper. Fan blade, disk and casing are modeled using beam element. Craig-Bampton model reduction is applied to simplify the model. Penalty method mixed with golden section method is created and used for contact treatments. The interaction is initiated by the external forces acting on the casing. The casing is excited to two-, three- and four-nodal diameter vibration patterns, respectively. In order to capture the core of the problem, contact forces applied to the casing, and casing damping are neglected. Steady casing vibrations could thus be generated. Blade vibrations are calculated in a wide rotating speed range, maximum amplitudes are recorded and studied. The results show that the bladed-disk will have several vibration peaks in the calculated rotating speed range. To figure out the physical mechanisms of these peaks, Fourier spectrums as well as different bladed-disk materials are introduced. Almost all vibration peaks can be explained by three kinds of mechanisms found and summarized in this paper. Two of them are related to travelling waves and the third is related to harmonics. Speed and frequency margins that are related to blade-tip-rub induced vibrations are defined and analyzed. The findings and ideas shown in this paper can be used as a reference in engine preliminary structural design to avoid potential blade tip-rub induced damages.

Analytic Approximations to Nonlinear Boundary Value Problems Modeling Beam-Type Nano-Electromechanical Systems

2017 ◽  
Vol 72 (3) ◽  
pp. 201-206
Author(s):  
Li Zou ◽  
Songxin Liang ◽  
Yawei Li ◽  
David J. Jeffrey
Keyword(s):  
Boundary Value Problems ◽  
Nonlinear Boundary ◽  
Boundary Value ◽  
Parameter Method ◽  
Nonlinear Boundary Value Problems ◽  
Electromechanical Systems ◽  
Adomian Decomposition ◽  
Nonlinear Boundary Value ◽  
Beam Type ◽  
Two Parameter

AbstractNonlinear boundary value problems arise frequently in physical and mechanical sciences. An effective analytic approach with two parameters is first proposed for solving nonlinear boundary value problems. It is demonstrated that solutions given by the two-parameter method are more accurate than solutions given by the Adomian decomposition method (ADM). It is further demonstrated that solutions given by the ADM can also be recovered from the solutions given by the two-parameter method. The effectiveness of this method is demonstrated by solving some nonlinear boundary value problems modeling beam-type nano-electromechanical systems.

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