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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Analyzing the Effects of Atmospheric Turbulent Fluctuations on the Wake Structure of Wind Turbines and Their Blade Vibrational Dynamics

In recent trends, a rising demand for renewable energy has driven wind turbines to larger proportions, where lighter blade designs are often adopted to reduce the costs associated with logistics and production. This causes modern utility-scale wind turbine blades to be inherently more flexible, and their amplified aeroelastic sensitivity results in complex multi-physics reactions to variant atmospheric conditions, including dynamic patterns of aerodynamic loading at the rotor and vortex structure evolutions within the wake. In this paper, we analyze the influence of inflow variance for wind turbines with large, flexible rotors through simulations of the National Rotor Testbed (NRT) turbine, located at Sandia National Labs’ Scaled Wind Farm Technology (SWiFT) facility in Lubbock, Texas. The Common Ordinary Differential Equation Framework (CODEF) modeling suite is used to simulate wind turbine aeroelastic oscillatory behavior and wind farm vortex wake interactions for a range of flexible NRT blade variations, operating in differing conditions of variant atmospheric flow. CODEF solutions of turbine operation in Steady-In-The-Average (SITA) wind conditions are compared to SITA wind conditions featuring a controlled gust-like pulse overimposed, to isolate the effects of typical wind fluctuations. Finally, simulations of realistic time-varying wind conditions from SWiFT meteorological tower measurements are compared to the solutions of SITA wind conditions. These increasingly complex atmospheric inflow variations are tested to show the differing effects evoked by various patterns of spatiotemporal atmospheric flow fluctuations. An analysis is presented for solutions of wind turbine aeroelastic response and vortex wake evolution, to elucidate the consequences of variant inflow, which pertain to wind turbine dynamics at an individual and farm-collective scale. The comparisons of simulated farm flow for SITA and measured fluctuating wind conditions show that certain regions of the wake contain up to a 12% difference in normalized axial velocity, due to the introduction of wind fluctuations. The findings of this study prove valuable for practical applications in wind farm control and optimization strategies, with particular significance for modern utility-scale wind power plants operating in variant atmospheric conditions.

Farrell, Alayna (ORCID:000000023555720X)↗
DOE OSTI2015

Aerodynamic and aeroacoustic for wind turbine

This paper describes a hybrid approach forpredicting noise radiated from the rotating Wind Turbine (HAWT) blades, where the sources are extracted from an unsteady Reynolds-Averaged-Navier Stocks (URANS) simulation, ANSYS CFX 11.0, was used to calculate The near-field flow parameters around the blade surface that are necessary for FW-H codes. Comparisons with NREL Phase II experimental results are presented with respect to the pressure distributions for validating a capacity of the solver to calculate the near-field flow on and around the wind turbine blades, The results show that numerical data have a good agreement with experimental. The acoustic pressure, presented as a sum of thickness and loading noise components, is analyzed by means of a discrete fast Fourier transformation for the presentation of the time acoustic time histories in the frequency domain. The results convincingly show that dipole source noise is the dominant noise source for this wind turbine.

17 WIND ENERGY↗
DOE OSTI2015

Structural Testing at the NWTC Helps Improve Blade Design and Increase System Reliability

Since 1990, the National Renewable Energy Laboratory's (NREL's) National Wind Technology Center (NWTC) has tested more than 150 wind turbine blades. NWTC researchers can test full-scale and subcomponent articles, conduct data analyses, and provide engineering expertise on best design practices. Structural testing of wind turbine blades enables designers, manufacturers, and owners to validate designs and assess structural performance to specific load conditions. Rigorous structural testing can reveal design and manufacturing problems at an early stage of development that can lead to overall improvements in design and increase system reliability.

17 WIND ENERGY↗
DOE OSTI2017

Maintaining Balance: The Increasing Role of Energy Storage for Renewable Integration

For nearly a century, global power systems have focused on three key functions: generating, transmitting, and distributing electricity as a real-time commodity. Physics requires that electricity generation always be in real-time balance with load-despite variability in load on time scales ranging from subsecond disturbances to multiyear trends. With the increasing role of variable generation from wind and solar, the retirement of fossil-fuel-based generation, and a changing consumer demand profile, grid operators are using new methods to maintain this balance.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2012

Incorporation of Multi-Member Substructure Capabilities in FAST for Analysis of Offshore Wind Turbines: Preprint

FAST, developed by the National Renewable Energy Laboratory (NREL), is an aero-hydro-servo-elastic tool widely used for analyzing onshore and offshore wind turbines. This paper discusses recent modifications made to FAST to enable the examination of offshore wind turbines with fixed-bottom, multi-member support structures (which are commonly used in transitional-depth waters). ; This paperaddresses the methods used for incorporating the hydrostatic and hydrodynamic loading on multi-member structures in FAST through its hydronamic loading module, HydroDyn. Modeling of the hydrodynamic loads was accomplished through the incorporation of Morison and buoyancy loads on the support structures. Issues addressed include how to model loads at the joints of intersecting members and ontapered and tilted members of the support structure. Three example structures are modeled to test and verify the solutions generated by the modifications to HydroDyn, including a monopile, tripod, and jacket structure. Verification is achieved through comparison of the results to a computational fluid dynamics (CFD)-derived solution using the commercial software tool STAR-CCM+.

17 WIND ENERGY↗
DOE OSTI2018

System Levelized Cost of Energy Analysis for Floating Offshore Vertical-Axis Wind Turbines

The levelized cost of energy for an offshore wind plant consisting of floating vertical-axis wind turbines is studied in this report. A 5 MW Darrieus vertical-axis wind turbine rotor is used as the study turbine as this architecture was determined to have the greatest ability to reduce the system cost. The rotor structural design was used with blade manufacturing cost model studies to estimate its cost. A two-bladed, carbon fiber rotor was selected in this analysis since the lower topside mass resulted in a reduction of the platform costs which exceeded the increased rotor cost. A direct-drive, medium efficiency drivetrain was designed which represents 25% of the costs and 45% of the mass of the combined rotor/drivetrain system. A direct-drive, permanent magnet generator drivetrain was selected due to the improved reliability of this type of system, while the cost was not significantly higher than for geared drivetrains. A platform was designed by first identifying the optimal architecture for the vertical-axis wind turbine at a water depth of 150 m. A survey was performed of floating platform types, and six characteristic designs were analyzed which span the range of stability mechanisms available to floating systems. A multi-cellular tension-leg platform was identified as the lowest cost platform which additionally provided some interesting performance benefits. The small motions of the tension-leg platform benefit the system energy capture while limiting inertial loads placed on the rotor’s tower and blades. A final design was produced for the multi-cellular tension-leg platform considering operational fatigue, storm wind and wave conditions, and tow-out design cases. The driving design load was stability during tow-out while ballasting the platform. System levelized cost of energy was calculated, including operational expenses and balance of system costs estimated for the wind plant. Opportunities for reduction in the component costs are predicted and used to make projections of the system levelized cost of energy for future developments. The opportunities and challenges for floating vertical-axis wind turbines are identified by the system design and levelized cost of energy analysis.

17 WIND ENERGY↗
DOE OSTI2015

Significance of Dynamic and Transient Analysis in the Design and Operation of Hybrid Energy Systems

Energy systems were historically designed and operated with a specific energy conversion objective, while managing loads and resources. In the recent years, the increased utilization of non-dispatchable renewable sources such as wind and solar has played a role in power quality and the reliability of power systems. In order to mitigate the risk associated with the non-dispatchable resources an integrated approach, such as Hybrid Energy Systems (HES), has to be taken, integrating the loads and resource management between the traditional thermal power plants and the non-dispatchable resources. As our electric energy becomes more diverse in its generation resources, the HES with its operational control system, its real-time view and its dynamic decisions making will become an essential part of the integrated energy systems and improve the overall grid reliability. The operational constraints of the energy sources on both the thermal power plants and the non-dispatchable resources in HES, plays a vital role in the planning and design stage. It is an established fact that the choice of energy source depends on the available natural resources and possible infrastructure. A critical component of decision-making depends on the complementary nature and controllability of the energy sources to supply the load demands with high reliability. Controllability of complex HES to achieve desired performance and flexibility is implemented via coordinated control systems while simultaneously generating electricity and other useful products such as useful heat or hydrogen. These systems are based on instrumentation, signal processing, control theory, and engineering system design. The entire HES along with the control systems are characterized by widely varying time constants. Hence, for a well-coordinated control and operation, we propose physics based modeling of the subsystems to assist in a dynamic and transient analysis. Dynamic and transient analysis in real and non-real time domain of the potential sources is capable of providing satisfactory results at the feasibility analysis stage. A simplified HES consisting of complementary energy sources is used to demonstrate the proposed approach. Suitable real time simulations to perform dynamic and transient analysis will be performed to verify results from the non-real time analysis. The role of such analyses, especially the real time dynamic and transient analysis for manual controls is elaborated. It is also discussed that faster than real time simulation will pave the future for controller rooms and hence manual control procedures. Multiple tools such as Real Time Simulator, Matlab®, Simulink®, PSCAD®, MOOSE, etc. are expected to be used for the HES analysis.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

A Vortex Step Method for Nonlinear Airfoil Polar Data as Implemented in KiteAeroDyn: Preprint

This paper summarizes the underlying theory in the recently developed KiteAeroDyn (KiteAD) module, which is part of KiteFAST (KiteFAST), a numerical simulation tool that is currently being developed at the NREL. KiteFAST is intended for the simulation of airborne wind energy systems (e.g., energy kites). KiteAD implements an innovative vortex step method for the calculation of aerodynamic loads on all of the lifting surfaces of the kite, which is capable of accounting for two-dimensional viscous effects through the use of nonlinear airfoil polars. Considering nonlinear airfoil polar data allows for the modeling of flap or other moving-surface deflections, as well as for the modelling of inflow conditions with larger angles angles of attack. From preliminary verification against other existing codes that can solve for lift distribution on lifting surfaces, the results of the newly implemented method proved to be numerically robust and computationally inexpensive, thus ideal for aeroelastic design and analysis applications.

17 WIND ENERGY↗
NASA NTRS1975

An interactive graphics program to retrieve, display, compare, manipulate, curve fit, difference and cross plot wind tunnel data

The Aerodynamic Data Analysis and Integration System (ADAIS), developed as a highly interactive computer graphics program capable of manipulating large quantities of data such that addressable elements of a data base can be called up for graphic display, compared, curve fit, stored, retrieved, differenced, etc., was described. The general nature of the system is evidenced by the fact that limited usage has already occurred with data bases consisting of thermodynamic, basic loads, and flight dynamics data. Productivity using ADAIS of five times that for conventional manual methods of wind tunnel data analysis is routinely achieved. In wind tunnel data analysis, data from one or more runs of a particular test may be called up and displayed along with data from one or more runs of a different test. Curves may be faired through the data points by any of four methods, including cubic spline and least squares polynomial fit up to seventh order.

Elliott, R. D.↗
NASA NTRS1975

Results of a Pressure Loads Investigation on a 0.030-scale Model (47-OTS) of the Integrated Space Shuttle Vehicle Configuration 5 in the NASA Ames Research Center 11 by 11 Foot Leg of the Unitary Plan Wind Tunnel (IA81A), Volume 1

Results of wind tunnel tests on a 0.030-scale model of the integrated space shuttle vehicle configuration 5 are presented. Testing was conducted in the NASA Ames Research Center 11 x 11 foot leg of the Unitary Plan Wind Tunnel to investigate pressure distributions for airloads analyses at Mach numbers from 0.9 through 1.4. Angles of attack and sideslip were varied from -6 to +6 degrees.

Chee, E.↗