Publications

81 Results
Skip to search filters

Wind Turbine Wakes

Kelley, Christopher L.; Maniaci, David C.; Resor, Brian R.

The total energy produced by a wind farm depends on the complex interaction of many wind turbines operating in proximity with the turbulent atmosphere. Sometimes, the unsteady forces associated with wind negatively influence power production, causing damage and increasing the cost of producing energy associated with wind power. Wakes and the motion of air generated by rotating blades need to be better understood. Predicting wakes and other wind forces could lead to more effective wind turbine designs and farm layouts, thereby reducing the cost of energy, allowing the United States to increase the installed capacity of wind energy. The Wind Energy Technologies Department at Sandia has collaborated with the University of Minnesota to simulate the interaction of multiple wind turbines. By combining the validated, large-eddy simulation code with Sandia’s HPC capability, this consortium has improved its ability to predict unsteady forces and the electrical power generated by an array of wind turbines. The array of wind turbines simulated were specifically those at the Sandia Scaled Wind Farm Testbed (SWiFT) site which aided the design of new wind turbine blades being manufactured as part of the National Rotor Testbed project with the Department of Energy.

More Details
TYPE Other Report YEAR 2015
OSTIDOI

Effects of increasing tip velocity on wind turbine rotor design

Resor, Brian R.; Maniaci, David C.; Berg, Jonathan C.; Richards, Phillip W.

A reduction in cost of energy from wind is anticipated when maximum allowable tip velocity is allowed to increase. Rotor torque decreases as tip velocity increases and rotor size and power rating are held constant. Reduction in rotor torque yields a lighter weight gearbox, a decrease in the turbine cost, and an increase in the capacity for the turbine to deliver cost competitive electricity. The high speed rotor incurs costs attributable to rotor aero-acoustics and system loads. The increased loads of high speed rotors drive the sizing and cost of other components in the system. Rotor, drivetrain, and tower designs at 80 m/s maximum tip velocity and 100 m/s maximum tip velocity are created to quantify these effects. Component costs, annualized energy production, and cost of energy are computed for each design to quantify the change in overall cost of energy resulting from the increase in turbine tip velocity. High fidelity physics based models rather than cost and scaling models are used to perform the work. Results provide a quantitative assessment of anticipated costs and benefits for high speed rotors. Finally, important lessons regarding full system optimization of wind turbines are documented.

More Details
TYPE SAND Report YEAR 2014
OSTIDOI

Definition of the National Rotor Testbed: An Aeroelastically relevant research-scale wind turbine rotor

32nd ASME Wind Energy Symposium

Resor, Brian R.; Maniaci, David C.

Sandia is designing a set of modern, research-quality blades for use on the V27 turbines at the DOE/SNL SWiFT site at Texas Tech University in Lubbock, Texas. The new blades will replace OEM blades and will be a publicly available resource for subscale rotor research. Features of the new blades do not represent the optimal design for a V27 rotor, but are determined by aeroelastic scaling of relevant parameters and design drivers from a representative megawatt-scale rotor. Scaling parameters and design drivers are chosen based two factors: 1) retrofit to the existing SWiFT turbines and 2) replicate rotor loads and wake formation of a utility scale turbine to support turbine -turbine interaction research at multiple scales. The blades are expected to provide a publicly available baseline blade design which will enable increased participation in future blade research as well as accelerated hardware manufacture and test for demonstration of innovation. This paper discusses aeroelastic scaling approaches, a rotor design process and a summary of design concepts.

More Details
TYPE Conference YEAR 2014
ScopusOSTI

Structural health and prognostics management for the enhancement of offshore wind turbine operations and maintenance strategies

Wind Energy

Griffith, Daniel G.; Resor, Brian R.; Paquette, Joshua P.

Offshore wind turbines are an attractive source for clean and renewable energy for reasons including their proximity to population centers and higher capacity factors. One obstacle to the more widespread installation of offshore wind turbines in the USA, however, is that recent projections of offshore operations and maintenance costs vary from two to five times the land-based costs. One way in which these costs could be reduced is through use of a structural health and prognostics management (SHPM) system as part of a condition-based maintenance paradigm with smart loads management. Our paper contributes to the development of such strategies by developing an initial roadmap for SHPM, with application to the blades. One of the key elements of the approach is a multiscale simulation approach developed to identify how the underlying physics of the system are affected by the presence of damage and how these changes manifest themselves in the operational response of a full turbine. A case study of a trailing edge disbond is analysed to demonstrate the multiscale sensitivity of damage approach and to show the potential life extension and increased energy capture that can be achieved using simple changes in the overall turbine control and loads management strategy. Finally, the integration of health monitoring information, economic considerations such as repair costs versus state of health, and a smart loads management methodology provides an initial roadmap for reducing operations and maintenance costs for offshore wind farms while increasing turbine availability and overall profit.

More Details
TYPE Journal Article YEAR 2013
OSTIDOI

Definition of a 5MW/61.5m wind turbine blade reference model

Resor, Brian R.

A basic structural concept of the blade design that is associated with the frequently utilized %E2%80%9CNREL offshore 5-MW baseline wind turbine%E2%80%9D is needed for studies involving blade structural design and blade structural design tools. The blade structural design documented in this report represents a concept that meets basic design criteria set forth by IEC standards for the onshore turbine. The design documented in this report is not a fully vetted blade design which is ready for manufacture. The intent of the structural concept described by this report is to provide a good starting point for more detailed and targeted investigations such as blade design optimization, blade design tool verification, blade materials and structures investigations, and blade design standards evaluation. This report documents the information used to create the current model as well as the analyses used to verify that the blade structural performance meets reasonable blade design criteria.

More Details
TYPE SAND Report YEAR 2013
OSTIDOI

Structural health and prognostics management for offshore wind turbines :

Griffith, Daniel G.; Resor, Brian R.; Paquette, Joshua P.

Operations and maintenance costs for offshore wind plants are expected to be significantly higher than the current costs for onshore plants. One way in which these costs may be able to be reduced is through the use of a structural health and prognostic management system as part of a condition based maintenance paradigm with smart load management. To facilitate the creation of such a system a multiscale modeling approach has been developed to identify how the underlying physics of the system are affected by the presence of damage and how these changes manifest themselves in the operational response of a full turbine. The developed methodology was used to investigate the effects of a candidate blade damage feature, a trailing edge disbond, on a 5-MW offshore wind turbine and the measurements that demonstrated the highest sensitivity to the damage were the local pitching moments around the disbond. The multiscale method demonstrated that these changes were caused by a local decrease in the blades torsional stiffness due to the disbond, which also resulted in changes in the blades local strain field. Full turbine simulations were also used to demonstrate that derating the turbine power by as little as 5% could extend the fatigue life of a blade by as much as a factor of 3. The integration of the health monitoring information, conceptual repair cost versus damage size information, and this load management methodology provides an initial roadmap for reducing operations and maintenance costs for offshore wind farms while increasing turbine availability and overall profit.

More Details
TYPE SAND Report YEAR 2012
OSTIDOI

Simulating the entire life of an offshore wind turbine

European Wind Energy Conference and Exhibition 2012, EWEC 2012

Barone, Matthew; Paquette, Joshua P.; Resor, Brian R.; Manuel, Lance; Nguyen, Hieu

Sixty-three years of aero-hydro-elastic loads simulations are demonstrated for a 5 MW offshore wind turbine deployed in shallow water. This large amount of simulation was made possible through the use of a high-performance computing cluster. The resulting one-hour extreme load distributions are examined; the extensive number of one-hour realizations allows for direct estimation of fifty-year return loads, without resorting to extrapolation. This type of simulation study opens up new possibilities for developing wind turbine design standards and discovering physical mechanisms that lead to extreme loads on wind turbine components.

More Details
TYPE Conference YEAR 2012
ScopusOSTI

Mapping of 1D beam loads to the 3D wind blade for buckling analysis

Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

Berg, Jonathan C.; Paquette, Joshua P.; Resor, Brian R.

This paper discusses the development of a consistent methodology for mapping one-dimensional distributed beam loads to a three-dimensional shell structure. The resultant force distribution is a linear approximation to the actual aerodynamic pressure distribution but is sufficient to obtain accurate strain and displacement results. The purpose of the mapping technique is to apply more realistic wind loads to the shell model of a wind turbine blade without the need to set up and run expensive computational fluid dynamics or fluid structure interaction problems. Subsequent buckling and stress analysis reveal how this approach compares to other simplified methods of defining the loads. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

More Details
TYPE Conference YEAR 2011
ScopusOSTI

System ID modern control algorithms for active aerodynamic load control and impact on gearbox loading

Resor, Brian R.; Berg, Jonathan C.

Prior work on active aerodynamic load control (AALC) of wind turbine blades has demonstrated that appropriate use of this technology has the potential to yield significant reductions in blade loads, leading to a decrease in wind cost of energy. While the general concept of AALC is usually discussed in the context of multiple sensors and active control devices (such as flaps) distributed over the length of the blade, most work to date has been limited to consideration of a single control device per blade with very basic Proportional Derivative controllers, due to limitations in the aeroservoelastic codes used to perform turbine simulations. This work utilizes a new aeroservoelastic code developed at Delft University of Technology to model the NREL/Upwind 5 MW wind turbine to investigate the relative advantage of utilizing multiple-device AALC. System identification techniques are used to identify the frequencies and shapes of turbine vibration modes, and these are used with modern control techniques to develop both Single-Input Single-Output (SISO) and Multiple-Input Multiple-Output (MIMO) LQR flap controllers. Comparison of simulation results with these controllers shows that the MIMO controller does yield some improvement over the SISO controller in fatigue load reduction, but additional improvement is possible with further refinement. In addition, a preliminary investigation shows that AALC has the potential to reduce off-axis gearbox loads, leading to reduced gearbox bearing fatigue damage and improved lifetimes.

More Details
TYPE Conference YEAR 2010
OSTI

An evaluation of wind turbine blade cross section analysis techniques

Resor, Brian R.; Paquette, Joshua P.; Laird, Daniel L.; Griffith, Daniel G.

The blades of a modern wind turbine are critical components central to capturing and transmitting most of the load experienced by the system. They are complex structural items composed of many layers of fiber and resin composite material and typically, one or more shear webs. Large turbine blades being developed today are beyond the point of effective trial-and-error design of the past and design for reliability is always extremely important. Section analysis tools are used to reduce the three-dimensional continuum blade structure to a simpler beam representation for use in system response calculations to support full system design and certification. One model simplification approach is to analyze the two-dimensional blade cross sections to determine the properties for the beam. Another technique is to determine beam properties using static deflections of a full three-dimensional finite element model of a blade. This paper provides insight into discrepancies observed in outputs from each approach. Simple two-dimensional geometries and three-dimensional blade models are analyzed in this investigation. Finally, a subset of computational and experimental section properties for a full turbine blade are compared.

More Details
TYPE Conference YEAR 2010
OSTI

Handbook on dynamics of jointed structures

Gregory, Danny L.; Starr, Michael J.; Resor, Brian R.; Jew, Michael J.; Lauffer, James P.

The problem of understanding and modeling the complicated physics underlying the action and response of the interfaces in typical structures under dynamic loading conditions has occupied researchers for many decades. This handbook presents an integrated approach to the goal of dynamic modeling of typical jointed structures, beginning with a mathematical assessment of experimental or simulation data, development of constitutive models to account for load histories to deformation, establishment of kinematic models coupling to the continuum models, and application of finite element analysis leading to dynamic structural simulation. In addition, formulations are discussed to mitigate the very short simulation time steps that appear to be required in numerical simulation for problems such as this. This handbook satisfies the commitment to DOE that Sandia will develop the technical content and write a Joints Handbook. The content will include: (1) Methods for characterizing the nonlinear stiffness and energy dissipation for typical joints used in mechanical systems and components. (2) The methodology will include practical guidance on experiments, and reduced order models that can be used to characterize joint behavior. (3) Examples for typical bolted and screw joints will be provided.

More Details
TYPE SAND Report YEAR 2009
OSTIDOI

Experimental Investigations of an Inclined Lap-Type Bolted Joint

Gregory, Danny L.; Gregory, Danny L.; Resor, Brian R.; Coleman, Ronald G.; Smallwood, David O.

The dynamic response of critical aerospace components is often strongly dependent upon the dynamic behavior of bolted connections that attach the component to the surrounding structure. These bolted connections often provide the only structural load paths to the component. The bolted joint investigated in this report is an inclined lap-type joint with the interface inclined with respect to the line of action of the force acting on the joint. The accurate analytical modeling of these bolted connections is critical to the prediction of the response of the component to normal and high-level shock environmental loadings. In particular, it is necessary to understand and correctly model the energy dissipation (damping) of the bolted joint that is a nonlinear function of the forces acting on the joint. Experiments were designed and performed to isolate the dynamics of a single bolted connection of the component. Steady state sinusoidal and transient experiments were used to derive energy dissipation curves as a function of input force. Multiple assemblies of the bolted connection were also observed to evaluate the variability of the energy dissipation of the connection. These experiments provide insight into the complex behavior of this bolted joint to assist in the postulation and development of reduced order joint models to capture the important physics of the joint including stiffness and damping. The experiments are described and results presented that provide a basis for candidate joint model calibration and comparison.

More Details
TYPE Report YEAR 2003
OSTIDOI
81 Results
81 Results