Dynamics-Based Health Monitoring of Wind Turbine Rotor Blades Using Integrated Inertial Sensors

2012 ◽  
Author(s):  
Scott R. Dana ◽  
Douglas E. Adams
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Modal Analysis ◽  
Turbine Rotor ◽  
Vertical Shear ◽  
Aerodynamic Load ◽  
Test Bed ◽  
Horizontal Axis Wind Turbine ◽  
Structural Dynamic ◽  
Wind Turbine Rotor

By analyzing the rotor structural dynamic response of a wind turbine, this research aims to improve decision making in operation and maintenance. To illustrate the potential of this measurement technique, a horizontal axis wind turbine test-bed is used to experimentally simulate the rotor structural dynamic response to uniform flow as well as horizontal and vertical shear flow across the rotor plane. The structural dynamic characteristics of the wind turbine rotor are described in the context of modal analysis where each mode of vibration occurs at a particular frequency with a particular modal deflection shape. These deflection shapes facilitate the effectiveness with which a given aerodynamic load couples into the rotor to produce mechanical power in addition to vibrations of the rotor. Operational modal analysis is used to explore the effects of changes in the wind state on the sensitivity of condition monitoring data to two types of damages in the turbine rotor, ice accretion and blade root cracking. Additionally, the degree to which various damage mechanisms can be identified in the presence of yaw and pitch set points is analyzed. It is shown that certain frequencies in the measured response using the flap, edgewise, and span directions of the wind turbine are sensitive to a change in condition of the rotor for use in detecting that type of damage. By analyzing the changes in the modal response amplitudes, the type of damage present in the rotor system can also be classified.

Model Identification and Operating Load Characterization for a Small Horizontal Axis Wind Turbine Rotor Using Integrated Blade Sensors

2010 ◽  
Author(s):  
Scott Dana ◽  
Joseph Yutzy ◽  
Douglas E. Adams
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Rotor Blade ◽  
Model Identification ◽  
Turbine Rotor ◽  
Forced Response ◽  
Horizontal Axis ◽  
Horizontal Axis Wind Turbine ◽  
And Control ◽  
Wind Turbine Rotor

One of the primary challenges in diagnostic health monitoring and control of wind turbines is compensating for the variable nature of wind loads. Given the sometimes large variations in wind speed, direction, and other operational variables (like wind shear), this paper proposes a data-driven, online rotor model identification approach. A 2 m diameter horizontal axis wind turbine rotor is first tested using experimental modal analysis techniques. Through the use of the Complex Mode Indication Function, the dominant natural frequencies and mode shapes of dynamic response of the rotor are estimated (including repeated and pseudo-repeated roots). The free dynamic response properties of the stationary rotor are compared to the forced response of the operational rotor while it is being subjected to wind and rotordynamic loads. It is demonstrated that both narrowband (rotordynamic) and broadband (wind driven) responses are amplified near resonant frequencies of the rotor. Blade loads in the flap direction of the rotor are also estimated through matrix inversion for a simulated set of rotor blade input forces and for the operational loading state of the wind turbine in a steady state condition. The analytical estimates are shown to be accurate at frequencies for which the ordinary coherence functions are near unity. The loads in operation are shown to be largest at points mid-way along the span of the blade and on one of the three blades suggesting this method could be used for usage monitoring. Based on these results, it is proposed that a measurement of upstream wind velocity will provide enhanced models for diagnostics and control by providing a leading indicator of disturbances in the loads.

Navier-Stokes and Comprehensive Analysis Performance Predictions of the NREL Phase VI Experiment

2003 ◽  
Author(s):  
Earl P. N. Duque ◽  
Michael D. Burklund ◽  
Wayne Johnson
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Performance Predictions ◽  
Nasa Ames Research ◽  
Nrel Phase Vi ◽  
Wind Turbine Rotor

A vortex lattice code, CAMRAD II, and a Reynolds-Averaged Navier-Stoke code, OVERFLOW-D2, were used to predict the aerodynamic performance of a two-bladed horizontal axis wind turbine. All computations were compared with experimental data that was collected at the NASA Ames Research Center 80-by 120-Foot Wind Tunnel. Computations were performed for both axial as well as yawed operating conditions. Various stall delay models and dynamics stall models were used by the CAMRAD II code. Comparisons between the experimental data and computed aerodynamic loads show that the OVERFLOW-D2 code can accurately predict the power and spanwise loading of a wind turbine rotor.

scholarly journals Full HAWT rotor CFD simulations using different RANS turbulence models compared with actuator disk and experimental measurements

2017 ◽  
Author(s):  
Nikolaos Stergiannis ◽  
Jeroen van Beeck ◽  
Mark C. Runacres
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Experimental Measurements ◽  
Horizontal Axis Wind Turbine ◽  
Cfd Simulations ◽  
Disk Model ◽  
Actuator Disk ◽  
Wind Turbine Rotor

Abstract. The development of large-scale wind energy projects has created the demand for increasingly accurate and efficient models that limit a project's uncertainties and risk. Wake effects are of great importance and are relevant for the optimization of wind farms. Despite a growing body of research, there are still many open questions and challenges to overcome. In computational modelling, there are always numerous input parameters such as material properties, geometry, boundary conditions, initial conditions, turbulence modelling etc. whose estimation is difficult and their values are often inaccurate or uncertain. Due to the lack of information of several sources, e.g., uncertainties present in operating conditions as well as in the mathematical modelling, the computational output is also uncertain. It is therefore very important to validate the mathematical models with experiments performed in controlled conditions. In the present paper, the single wake characteristics of a Horizontal-Axis Wind Turbine Rotor (HAWT) and their spatial evolution are investigated with different Computational Fluid Dynamics (CFD) modelling approaches and compared to experimental measurements. The steady state 3-D Reynolds-Averaged Navier Stokes (RANS) equations are solved in the open-source platform OpenFOAM, using different turbulence closure schemes. For the full-rotor CFD simulations, the Multiple Reference Frames (MRF) approach was used to model the rotation of the blades. For the simplified cases, an actuator disk model was used with the experimentally measured thrust (CT) and power (CP) coefficient values. The performance of each modelling approach is compared with experimental wind tunnel wake measurements from the 4th blind test organized by NOWITECH and NORCOWE in 2015. Numerical results are compared with experimental data along three horizontal lines downstream, covering all the wake regions. Wake predictions are shown to be very sensitive to the choice of the RANS turbulence model. For most cases, the ADM under-predicts the velocity deficit, except for the case of RNG k-ε which showed a superb performance in the mid and far wake. The full wind turbine rotor simulations showed good agreement to the experimental data, mainly in the near wake, amplifying the differences between the simplified models.

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