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Lackner, Matthew A.

Publications and source records attributed to Lackner, Matthew A..

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

A Biomimetic Ultrasonic Whistle for Use as a Bat Deterrent on Wind Turbines

Our project goal was to design a novel mechanical ultrasonic deterrent for use on wind turbines in order to reduce bat fatalities around these structures. Our proposed deterrent design would be composed of a series of ultrasonic pulse generators, or whistles, affixed to a wind turbine blade, which produce ultrasound through mechanical means. The whistles would produce sounds mimicking the spectrotemporal patterns of bat echolocation pulses, thereby enhancing the bats’ ability to detect, localize and avoid the moving blades. These whistles are intended to be operated passively, blown by the wind, and to be positioned at intervals along a turbine blade. Because the source of sound generation will be mechanical in nature, these devices will require no external power source, should require little maintenance, and will be small and cost-effective.

17 WIND ENERGY↗
DOE OSTI2021

Floating platform effects on power generation in spar and semisubmersible wind turbines

The design and financing of commercial-scale floating offshore wind projects require a better understanding of how power generation differs between newer floating turbines and well-established fixed-bottom turbines. In floating turbines, platform mobility causes additional rotor motion that can change the time-averaged power generation. In this work, OpenFAST simulations examine the power generated by the National Renewable Energy Laboratory's 5-MW reference turbine mounted on the OC3-UMaine spar and OC4-DeepCWind semisubmersible floating platforms, subjected to extreme irregular waves and below-rated turbulent inflow wind from large-eddy simulations of a neutral atmospheric boundary layer. For these below-rated conditions, average power generation in floating turbines is most affected by two types of turbine displacements: an average rotor pitch angle that reduces power, caused by platform pitch; and rotor motion upwind-downwind that increases power, caused by platform surge and pitch. The relative balance between these two effects determines whether a floating platform causes power gains or losses compared to a fixed-bottom turbine; for example, the spar creates modest (3.1%–4.5%) power gains, whereas the semisubmersible creates insignificant (0.1%–0.2%) power gains for the simulated conditions. Furthermore, platform surge and pitch motions must be analyzed concurrently to fully capture power generation in floating turbines, which is not yet universal practice. Finally, a simple analytical model for predicting average power in floating turbines under below-rated wind speeds is proposed, incorporating effects from both the time-averaged pitch displacement and the dynamic upwind-downwind displacements.

17 WIND ENERGY↗
DOE OSTI2019

Hurricane Eyewall Winds and Structural Response of Wind Turbines

This paper describes the analysis of a wind turbine and support structure subject to simulated hurricane wind fields. The hurricane wind fields, which result from a Large Eddy Simulation of a hurricane, exhibit features such as very high gust factors (> 1.7), rapid direction changes (30 degrees in 30 sec) and substantial veer. Wind fields including these features have not previously been used in an analysis of a wind turbine and their effect on structural loads may be an important driver of enhanced design considerations. With a focus on blade root loads and tower base loads, the simulations show that these features of hurricane wind fields can lead to loads that are substantially in excess of those that would be predicted were wind fields with equally high mean wind speeds but without associated direction change and veer used in the analysis. This result, if further verified for a range of hurricane and tropical storm simulations, should provide an impetus for revisiting design standards.

17 WIND ENERGY↗
DOE OSTI2016

An Investigation of Passive and Semi-Active Tuned Mass Dampers for a Tension Leg Platform Floating Offshore Wind Turbine in ULS Conditions

Offshore Wind Turbines (OWTs) are subjected to complex external loadings caused by combined wind and wave sources. The application of structural damping control techniques to OWTs using Tuned Mass Dampers (TMDs) has shown to be effective in reducing the integrated system loads and accelerations. In this work, the impact of passive and semi-active (S-A) TMD’s applied to both fixed-bottom (monopile) and floating (tension leg platform) OWTs are evaluated under the Fatigue Limit State (FLS) and Ultimate Limit State (ULS). Different S-A control logics like ON/OFF state damping based on the ground hook (GH) control policy are implemented, and the frequency response of each algorithm is investigated. It is shown that the performance of each algorithm varies according to the load conditions such as FLS (normal operation) and ULS (idling state). Fully-coupled time domain simulations are conducted through the developed simulation tool for structural control integrated into the high-fidelity wind turbine design code, FASTv8. Compared to the passive TMD, it is shown that a S-A TMD results in higher load reductions, as well as, smaller strokes under both FLS and ULS conditions. In FLS analysis, the S-A TMD using Displacement Based Ground Hook (DB-GH) control is capable of reducing the fore-aft and side-to-side damage equivalent loads for the monopile substructure by approximately 12 % and 64 %, respectively. The ultimate loads at the tower base for the floating substructure (TLP) are also reduced by 9% with S-A TMD followed by Inverse Velocity Based Ground Hook control (IVB-GH). The dynamic characteristics and practical feasibility of a magnetorheological (MR) damper (for S-A control) are also evaluated.

17 WIND ENERGY↗
DOE OSTI2015

The creation of a comprehensive metocean data set for offshore wind turbine simulations: Comprehensive metocean data set

A database of meteorological and ocean conditions is presented for use in offshore wind energy research and design. The original data are from 23 ocean sites around the USA and were obtained from the National Data Buoy Center run by the National Oceanic and Atmospheric Administration. The data are presented in a processed form that includes the variables of interest for offshore wind energy design: wind speed, significant wave height, wave peak-spectral period, wind direction and wave direction. For each site, a binning process is conducted to create conditional probability functions for each of these variables. The sites are then grouped according to geographic location and combined to create three representative sites, including a West Coast site, an East Coast site and a Gulf of Mexico site. Both the processed data and the probability distribution parameters for the individual and representative sites are being hosted on a publicly available domain by the National Renewable Energy Laboratory, with the intent of providing a standard basis of comparison for meteorological and ocean conditions for offshore wind energy research worldwide.

17 WIND ENERGY↗
DOE OSTI2012

Offshore Wind Energy Systems Engineering Curriculum Development

Utility-scale electricity produced from offshore wind farms has the potential to contribute significantly to the energy production of the United States. In order for the U.S. to rapidly develop these abundant resources, knowledgeable scientists and engineers with sound understanding of offshore wind energy systems are critical. This report summarizes the development of an upper-level engineering course in "Offshore Wind Energy Systems Engineering." This course is designed to provide students with a comprehensive knowledge of both the technical challenges of offshore wind energy and the practical regulatory, permitting, and planning aspects of developing offshore wind farms in the U.S. This course was offered on a pilot basis in 2011 at the University of Massachusetts and the National Renewable Energy Laboratory (NREL), TU Delft, and GL Garrad Hassan have reviewed its content. As summarized in this report, the course consists of 17 separate topic areas emphasizing appropriate engineering fundamentals as well as development, planning, and regulatory issues. In addition to the course summary, the report gives the details of a public Internet site where references and related course material can be obtained. This course will fill a pressing need for the education and training of the U.S. workforce in this critically important area. Fundamentally, this course will be unique due to two attributes: an emphasis on the engineering and technical aspects of offshore wind energy systems, and a focus on offshore wind energy issues specific to the United States.

17 WIND ENERGY↗