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Experimental vibratory analysis of a rotating segmented wind turbine blade using common test equipment

JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2022年第12期44卷 1-10页

作者： Yangui, Majdi Bouaziz, Slim Taktak, Mohamed Debut, Vincent Antunes, Jose Haddar, Mohamed Ecole Natl Ingn Sfax Lab Rech Mecan Modelisat & Prod Sfax Tunisia Univ Lisbon C2TN Inst Super Tecn Lisbon Portugal

The vibration behavior of wind turbine blades (WTB) must be thoroughly investigated to avert undesirable dynamical phenomena under working conditions. This paper sets out an experimental frequency analysis of a rotating, scaled-down, segmented WTB. The purpose of the present work is twofold: (1) to devise a suitable experiment for the modal identification of a rotating component, when no rotor-specific test equipment is available, and (2) to validate a recently developed theoretical model for the dynamics of segmented wind turbine blades, through the modal parameters of the test blade identified for a given range of spinning velocity. The 3D fused deposition modeling technology was used to manufacture the blades segments, assembled with a steel threaded shaft and nut. A speed-controlled motor is used to scrutinize the influence of the rotation velocity on the blades modal parameters. To identify the blades modal frequencies and damping ratios, the eigensystem realization algorithm method was implemented. At rest, the blades natural frequencies were adjusted based on the additional assembly stiffness generated by the nut tightening torque. Because the modal identification of rotating components using conventional test equipment is a difficult task, a significant feature in this paper, beyond the obtained results, is the proposed original experimental technique to investigate the flapwise (out-of-plane) dynamical behavior of the rotating blades. The experimental results are compared with previous theoretical results, as a function of the blades spinning velocity, showing the significant influence of the rotation speed on the segmented WTB dynamical behavior, in agreement with the theoretical predictions.

关键词： Segmented wind turbine blades Rotor dynamics Experimental modal analysis Dynamical behavior eigensystem realization algorithm

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Improved Approximations to Wagner Function Using Sparse Identification of Nonlinear Dynamics

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AIAA JOURNAL 2022年第3期60卷 1691-1707页

作者： Dawson, Scott T. M. Brunton, Steven L. IIT Mech Mat & Aerosp Engn Chicago IL 60616 USA Univ Washington Mech Engn Seattle WA 98195 USA

The Wagner function represents the response in lift on an airfoil that is subject to a sudden change in conditions. While it plays a fundamental role in the development and application of unsteady aerodynamic methods, explicit expressions for this function are difficult to obtain. This has led to numerous proposed approximations that facilitate convenient and rapid computations. While these approximations can be sufficient for many purposes, their behavior is often noticeably different from the true Wagner function, especially for long-time asymptotic behavior. In particular, while many approximations have small maximum absolute error across all times, the relative error of the asymptotic behavior can be substantial. Here, we propose an alternative approximation methodology that is accurate for all times, for a variety of accuracy measures. This methodology casts the Wagner function as the solution of a nonlinear scalar ordinary differential equation, which is identified using a variant of the sparse identification of nonlinear dynamics algorithm. We show that this approach yields accurate approximations using either first- or second-order differential equations. We additionally demonstrate that this method can be applied to model the lift response for a more realistic aerodynamic system, featuring a finite thickness airfoil and nonplanar wake.

关键词： Nonlinear Dynamics Thin Airfoil Second Order Differential Equations Angle of Attack Stagnation Point Aerodynamic Configurations Starting Vortex Aerodynamic Flows eigensystem realization algorithm Frequency Domain

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Including Steady State Information in Reduced Order Modelling for Tiltrotor Aircraft Stability Analysis

Including Steady State Information in Reduced Order Modellin...

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AIAA Aviation Forum

作者： Bath, P. E. Gaitonde, A. L. Jones, D. P. Univ Bristol Dept Aerosp Engn Bristol BS8 1TR Avon England

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

This paper builds on the work previously carried out by the authors in exploring flight mechanics and aerodynamics coupled stability analysis of tiltrotor aircraft. The intention of the stability analysis via the coupled model, is to include the full dynamics of the wake in the stability analysis rather than reducing the aerodynamics to a set of first order stability derivatives as found in classical stability analysis. It is important to use the full dynamics in the stability analysis for tiltrotor aircraft due to the significant wake interaction with the airframe. In an effort to reduce the cost of computations and therefore be most applicable to early design stages of aircraft, the Unsteady Vortex Lattice Method (UVLM) is used as a lower fidelity aerodynamic solver and Reduced Order Models (ROMs) are used to limit the system size in the stability analysis. However, the main results of this research are independent of the solver used. This work specifically focuses on including steady state information in the ROM of the aerodynamics, which is coupled with the flight mechanics based on standard 3D rigid body equations of motion. The time averaged aerodynamic response is reduced using the eigensystem Realisation algorithm (ERA) as well as an adjusted ERA method that increases the importance of the steady state behaviour in the reduction. The stability derivatives of the aerodynamics were expected to show convergence to the steady step up response at lower ROM sizes when the steady state information is included in the ROM;however, the results obtained show little improvement in the convergence over the standard ERA method. This has been attributed to the aerodynamic simulation results;where the responses do not decay to the steady state, the ROM has sought to model this behaviour causing the stability derivatives to converge to a different value.

关键词： Tilt Rotor Aircraft Reduced Order Modelling Blade Passing Frequency eigensystem realization algorithm Flight Mechanics Proper Orthogonal Decomposition Aircraft Configurations Aeroplane Helicopters Vortex Rings

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On-line System Identification of Power System Linear Models

On-line System Identification of Power System Linear Models

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IEEE-Power-and-Energy-Society General Meeting (PESGM)

作者： Moreno-Corbea, J. A. Paternina, M. R. A. Rodales, D. Reyes, R. Zelaya, F. Zamora, A. Toledo, C. Castrillon, C. Sanchez, A. Univ Nacl Autonoma Mexico Mexico City Mexico U Michoacana Morelia Mexico U Nuevo Leon San Nicolas De Los Garza Mexico UTK Knoxville TN USA UIS Bucaramanga Colombia Univ Nacl Colombia Medellin Colombia Cinvestav Guadalajara Mexico

ISBN: (纸本)9781665464413

This paper deals with the provision of adequate testing simulation environments to facilitate the evaluation of new system identification techniques to enhance power system stability. It develops and implements a testing architecture for online system identification approaches, taking advantage of the use of two well-known computational programs (MatlabT and DIgSILENT PowerFactoryT). To ensure a reliable and optimal system identification, this platform exploits a mutually beneficial relationship among four well-established mathematical techniques (discrete Fourier transform, Teager-Kaiser energy operator, the fast Fourier transform, and eigensystem realization algorithm). Their symbioses can capture the synchrophasor information, detect the right disturbance instant, optimally extract the dominant frequency, and properly identify the Markov parameters that assemble the descriptor form of Multiple-Input and Multiple-Output (MIMO) linear systems for modeling modern power grids. Numerical results unveil the potential for recreating the real behavior of power systems;in particular, the proposed architecture can deal with any system identification technique to be tested.

关键词： Online system identification eigensystem realization algorithm Teager-Kaiser energy operator phasor estimation disturbance detection instant frequency computation

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Identification of Low-Frequency Oscillation Modes Using PMU Based Data-Driven Dynamic Mode Decomposition algorithm

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IEEE ACCESS 2021年 9卷 49434-49447页

作者： Zuhaib, Mohd Rihan, Mohd Aligarh Muslim Univ AMU ZH Coll Engn & Technol ZHCET Dept Elect Engn Aligarh 202002 Uttar Pradesh India

Power system inter-area oscillations curtail the power transferring capabilities of the transmission lines in a large interconnected power system. Accurate identification of dominant modes and associated contributing generators is important to avoid power system failures by taking appropriate remedial measures. This paper proposes a multi-channel Improved Dynamic Mode Decomposition (IDMD) algorithm-based modal analysis technique using Synchrophasors measurement. First, a reduced-order dynamic power system model is estimated and using this model dominant oscillation modes, corresponding modes shapes, damping ratio, coherent group of generators, participation factors are determined. To improve the accuracy data stacking technique is used to capture detailed information of the system. An optimal hard threshold technique is utilized to select the most optimal model order to avoid uncertainties due to the presence of high level of measurement noise. The study results show that the proposed algorithm gives an accurate and robust solution even in systems having high level of noise in the measurement data. The performance of the proposed technique is tested on simulated data from two-area four-machine system and wNAPS 41-bus 16-generator system with PMU measurements corrupted with different levels of measurement noise. To further strengthen the viewpoint, the proposed method is validated on real-time PMU measurement from ISO New England data to validate the accuracy of the proposed work.

关键词： Phasor measurement unit wide area monitoring system dynamic mode decomposition algorithm eigensystem realization algorithm low-frequency oscillations

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Experimental updating of a segmented wind turbine blade numerical model using the substructure method

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JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN 2021年第2期56卷 67-75页

作者： Yangui, Majdi Bouaziz, Slim Taktak, Mohamed Haddar, Mohamed Univ Sfax Natl Sch Engn Sfax Lab Mech Modelling & Prod LA2MP BP 1173-3038 Sfax Tunisia

During the development of the wind turbine system, blades are considered as the most critical components. The blades' dynamic characteristics must be investigated during the design process to improve their mechanical performance. This work presents an experimental updating of a segmented wind turbine blade numerical model. For this purpose, the blade segments were manufactured using the fused deposition 3D printing technology and assembled using a threaded spar and nut. For different values of the segments assembly load, the natural frequencies and damping ratios were identified using the eigensystem realization algorithm method. The dynamic behavior of the segmented blade was examined numerically using the three-node shell element, taking into consideration the additional stiffness generated by the applied assembly load. In this study, numerical and experimental modal analysis were used to identify the first five eigenfrequencies of the blade. To update the numerical model parameters, through the identified experimental results, an iterative method was developed based on the Craig-Bampton substructure approach. Results show that the blade natural frequencies are proportional to the segments assembly load. The application of the proposed method on the segmented blade numerical model updating shows that the present method is computationally efficient.

关键词： Segmented wind turbine blade finite element modeling experimental modal analysis eigensystem realization algorithm substructure method

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Filtered Integral Formulation of the Sparse Model Identification Problem

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2021年第2期45卷 232-247页

作者： Gueho, Damien Singla, Puneet Majji, Manoranjan Melton, Robert G. Penn State Univ Dept Aerosp Engn University Pk PA 16802 USA Texas A&M Univ Dept Aerosp Engn College Stn TX 77840 USA

This paper presents a generalized approach to identify the structure of governing nonlinear equations of motion from the time history of state variables and control functions. An integral form involving a low-pass filter in conjunction with sparse approximation tools is used to find a parsimonious model for underlying true dynamics from noisy measurement data. Two chaotic oscillatory systems as well as the well-known problem of identifying the central force field from position-only observation data are considered to validate the developed approach. The simulation results considered in the paper demonstrate the performance of the developed approach in learning unknown nonlinear system dynamics accurately with fewer basis functions as compared with classical least-squares regression techniques and emerging deep learning approaches. A comparison of the sparse identification techniques with classical least-squares regression techniques and emerging deep learning approaches reveals the utility of the methodology developed in the paper.

关键词： Neural Networks Mathematical Models eigensystem realization algorithm Gaussian White Noise Machine Learning Orbital Elements Satellites Earth ISS Second Order Differential Equations

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Performance comparison of data-driven reduced models for a single-injector combustion process

Performance comparison of data-driven reduced models for a s...

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AIAA Propulsion and Energy Forum / IEEE Electric Aircraft Technologies Symposium (EATS)

作者： Jain, Parikshit Kramer, Boris McQuarrie, Shane A. Univ Calif San Diego Dept Mech & Aerosp Engn La Jolla CA 92093 USA Univ Texas Austin Oden Inst Computat Engn & Sci Austin TX 78712 USA

ISBN: (数字)9781624106118

ISBN: (纸本)9781624106118

This paper derives a new data-driven reduced model for a challenging large-scale combustion simulation and offers a detailed performance comparison with two state-of-the-art reduced models that were previously developed for this application. In particular, we learn a physics-based cubic reduced-order model (ROM) via the operator inference framework (OPINF). The key to the efficiency and physics-based nature of the model lies in the use of variable transformations of the original highly nonlinear system that make the governing equations polynomial in the new variables. We compare this approach with a quadratic operator inference ROMand with dynamic mode decomposition with control (DMDc), a modal decomposition method that has been shown to work well in many fluid dynamical applications. An extensive comparison of these approaches yields interesting insights: in particular, we find that the cubic and quadratic models based on operator inference capture more high-frequency content of the system compared to DMDc;we also find that the presence of the cubic term in the operator inference ROM improves stability properties of the system. Each of the reduced models we examine are accurate and provide a significant computational speedup compared to the high-fidelity model.

关键词： Combustion Process Nonlinear Systems Singular Value Decomposition Combustors Combustion Chambers Specific Volume Computing eigensystem realization algorithm Machine Learning Frequency Domain

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The use of Periodic Reduced Order Models in Coupled Flight Mechanics Analysis of Tiltrotor Aircraft

The use of Periodic Reduced Order Models in Coupled Flight M...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Bath, P. E. Gaitonde, A. L. Jones, D. P. Univ Bristol Dept Aerosp Engn Bristol BS8 1TR Avon England

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

This manuscript outlines the production of a flight mechanics and reduced order aerodynamics coupled model for stability analysis of tiltrotor aircraft. By including time history effects this improves on classical stability analysis where a truncated Taylor expansion is used. These effects are important to consider due to the high amount of interaction of the wake from the rotating proprotors with the airframe. The flight mechanics is based on the 12 degrees of freedom 3D rigid body equations and the aerodynamic system is evaluated using the unsteady vortex lattice method. The aerodynamic model is reduced by two methods, using the eigen-system realisation algorithm for a linear time invariant approximation and a periodic reduced order model for the full linear time periodic system. The methodology is applied to a Bell XV-15 type tiltrotor aircraft in hover and forward flight and comparisons are drawn to prior stability analysis found in literature to assess the capability of the methodology. The coupled system indicates more instability when compared to the classical analysis, which suggests that the low order Taylor series expansion removes important dynamics attributed to the time history. The two model order reduction methods are compared which shows close correlation near to the stability boundary however a greater difference in the more unstable eigenvalues. This indicates that the time averaged model is more applicable to only lightly unstable situations.

关键词： Aircraft Flight Mechanics Tiltrotor Aircraft Blade Passing Frequency eigensystem realization algorithm Linear Time Invariant Aircraft Rotor Computational Fluid Dynamics Model Order Reduction Taylor Series Aeroplane

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Flow-Informed Vibration-Based Health Monitoring Technique

Flow-Informed Vibration-Based Health Monitoring Technique

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AIAA Aviation Forum and Exposition

作者： Wang, Tso-Kang Tripathi, Akriti Shahriar, Al Tavanashad, Vahid Kumar, Rajan Shoele, Kourosh Florida State Univ Florida A&M Univ Dept Mech Engn Joint Coll Engn Tallahassee FL 32310 USA

ISBN: (数字)9781624106101

ISBN: (纸本)9781624106101

Traditional structural health monitoring (SHM) techniques are often based on the assumption that the loading is either absent or can be treated as a stationary random variable. Many of the current SHM methods also necessitate strong actuation or an excessive number of sensors unsuitable for high-speed applications. Here we present an SHM technique that detects the type and extent of the damage in the presence of variable environmental conditions. The model is tested with virtual simulations, and data acquired from the structural sensors are analyzed with a time-frequency realization technique to retrieve the system information and the location and extent of potential damages. It is shown that the proposed method is robust to the environmental effects and can be used for high-speed applications.

关键词： Structural Health Monitoring Sensors Finite Element Modeling Empirical Mode Decomposition eigensystem realization algorithm Dynamic Response Boundary Layer Thickness Structural Damage Turbulent Flow Capacitance

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