Wind-induced loads on a launch vehicle
Launch vehicle design, considering tradeoffs between wind effects and analysis time
King, A.↗
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Wind and structural loads data measured on parabolic trough solar collectors at an operational power plant
Abstract Wind loading is a primary contributor to structural design costs of concentrating solar-thermal power collectors, such as heliostats and parabolic troughs. These structures must resist the mechanical forces generated by turbulent wind, while the reflector surfaces must maintain optimal optical performance. Studying wind-driven loads at a full-scale, operational concentrating solar-thermal power plant provides insights into the wind impact on the solar collector field beyond the capabilities of wind tunnel tests or state-of-the-art simulations. We conducted comprehensive field measurements of the atmospheric turbulent wind conditions and the resulting structural wind loads on parabolic troughs at the Nevada Solar One plant over a two-year period. The measurement setup included meteorological masts and structural load sensors on four trough rows. Additionally, a lidar scanned the horizontal plane above the trough field. In this study, we describe the high-resolution dataset characterizing the complex flow field and resulting structural loads. This first-of-its-kind dataset will enhance the understanding of wind loading on collector structures and will help in designing the next-generation solar collectors and photovoltaic trackers.
14 SOLAR ENERGY↗
Impacts of Providing Inertial Response on Dynamic Loads of Wind Turbine Drivetrains
There has been growing demand from the power industry for wind power plants to support power system operations. One such requirement is for wind turbines to provide ancillary services in the form of inertial response. When the grid frequency drops, it is essential for wind turbine generators (WTGs) to inject kinetic energy stored in their inertia into the grid to help arrest the frequency decline. However, the impacts of inertial response on the structural loads of the wind turbine have not been given much attention. To bridge this gap, this paper utilizes a holistic model for both fixed-speed and variable-speed WTGs by integrating the aeroelastic wind turbine model in FAST, developed by the National Renewable Energy Laboratory, with the electromechanical drivetrain model in SimDriveline and SimPowerSystems.
17 WIND ENERGY↗
Gaining Insights in Loading Events for Wind Turbine Drivetrain Prognostics
Wind energy is one of the largest sources of renewable energy in the world. To further reduce the operations and maintenance (O&M) costs of wind farms, it is essential to be able to accurately pinpoint the root causes of different failure modes of interest. An example of such a failure mode that is not yet fully understood is white etching cracks (WEC). This can cause the bearing lifetime to be reduced to 5–10% of its design value. Multiple hypotheses are available in literature concerning its cause. To be able to validate or disprove these hypotheses, it is essential to have historic high-frequency measurement data (e.g., load and vibration levels) available. In time, this will allow linking to the history of the turbine operating data with failure data. This paper discusses the dynamic loading on the turbine during certain events (e.g., emergency stops, run-ups, and during normal operating conditions). By combining the number of specific events that each turbine has seen with the severity of each event, it becomes possible to assess which turbines are most likely to show signs of damage.
49 EE - Wind and Water Power Program - Wind (EE-4W↗
In Situ Wind and Turbulence Measurements in a Field of Full-Size Parabolic Trough Solar Collectors
Concentrated Solar Power (CSP) is a promising method for using Solar power for electricity generation with thermal energy storage. One of the primary drivers of structural design costs of CSP collector structures is wind loading. To date, the design of these structures has relied on data from wind tunnels that do not adequately capture the dynamic effects observed at scale. NREL initiated a field measurement campaign at the operational Nevada Solar One (NSO) powerplant that uses parabolic troughs as solar collectors. The aim of the project is a detailed characterization of prevailing wind and turbulence conditions and resulting operational loads on parabolic troughs, providing insights on structural dynamic response, and generating a first-of-a-kind, comprehensive, high-resolution wind-loading dataset available for validating simulations of wind loading on collector structures. The measurements at NSO consist of Sonic anemometers on masts at different heights to characterize the incoming flow and conditions within and above the trough field, in combination with a Doppler Lidar scanning the horizontal plane above the troughs. The wind measurements at NSO have been continuously operating since October 2021 and provide a year-long dataset characterizing wind and turbulence conditions. The structural load measurements start in November 2022 and will complement the wind measurements. In this poster, we present first results of the wind measurement campaign by highlighting days with different atmospheric flow conditions. We identified three main factors altering the flow over the parabolic troughs: Wind speed, wind direction, and the angle of the parabolic troughs. The highest loads are expected when the wind blows perpendicular to the trough rows. In this case, the first rows experience the highest loads and block the subsequent rows, creating conditions with decreased wind speed and enhanced turbulence within the trough field. Also, turbulent length scales change. These affected conditions produce unique load cases on the structures that will be captured by the load measurements. If the wind blows along the trough rows, wind and turbulence conditions are less influenced by the troughs.
atmospheric turbulence↗
In Situ Wind and Turbulence Measurements in a Field of Full-Size Parabolic Trough Collectors
Concentrated Solar Power (CSP) is a promising method for using Solar power for electricity generation with thermal energy storage. One of the primary drivers of structural design costs of CSP collector structures is wind loading. To date, the design of these structures has relied on data from wind tunnels that do not adequately capture the dynamic effects observed at scale. NREL initiated a field measurement campaign at the operational Nevada Solar One (NSO) powerplant that uses parabolic troughs as solar collectors. The aim of the project is a detailed characterization of prevailing wind and turbulence conditions and resulting operational loads on parabolic troughs, providing insights on structural dynamic response, and generating a first-of-a-kind, comprehensive, high-resolution wind-loading dataset available for validating simulations of wind loading on collector structures. The measurements at NSO consist of Sonic anemometers on masts at different heights to characterize the incoming flow and conditions within and above the trough field, in combination with a Doppler Lidar scanning the horizontal plane above the troughs. The wind measurements at NSO have been continuously operating since October 2021 and provide a year-long dataset characterizing wind and turbulence conditions. The structural load measurements start in November 2022 and will complement the wind measurements. In this poster, we present first results of the wind measurement campaign by highlighting days with different atmospheric flow conditions. We identified three main factors altering the flow over the parabolic troughs: Wind speed, wind direction, and the angle of the parabolic troughs. The highest loads are expected when the wind blows perpendicular to the trough rows. In this case, the first rows experience the highest loads and block the subsequent rows, creating conditions with decreased wind speed and enhanced turbulence within the trough field. Also, turbulent length scales change. These affected conditions produce unique load cases on the structures that will be captured by the load measurements. If the wind blows along the trough rows, wind and turbulence conditions are less influenced by the troughs.
concentrated solar power↗
Visual display and alarm system for wind tunnel static and dynamic loads
A wind tunnel balance monitor and alarm system developed at NASA Ames Research Center will produce several beneficial results. The costs of wind tunnel delays because of inadvertent balance damage and the costs of balance repair or replacement can be greatly reduced or eliminated with better real-time information on the balance static and dynamic loading. The wind tunnel itself will have enhanced utility with the elimination of overly cautious limits on test conditions. The microprocessor-based system features automatic scaling and 16 multicolored LED bargraphs to indicate both static and dynamic components of the signals from eight individual channels. Five individually programmable alarm levels are available with relay closures for internal or external visual and audible warning devices and other functions such as automatic activation of external recording devices, model positioning mechanisms, or tunnel shutdown.
Hanly, Richard D.↗
Visual display and alarm system for wind tunnel static and dynamic loads
A wind tunnel balance monitor and alarm system developed at NASA Ames Research Center will produce several beneficial results. The costs of wind tunnel delays because of inadvertent balance damage and the costs of balance repair or replacement can be greatly reduced or eliminated with better real-time information on the balance static and dynamic loading. The wind tunnel itself will have enhanced utility with the elimination of overly cautious limits on test conditions. The microprocessor-based system features automatic scaling and 16 multicolored LED bargraphs to indicate both static and dynamic components of the signals from eight individual channels. Five individually programmable alarm levels are available with relay closures for internal or external visual and audible warning devices and other functions such as automatic activation of external recording devices, model positioning mechanism, or tunnel shutdown.
Hanly, Richard D.↗
Nonsteady Load Responses of Wind Turbines to Atmospheric and Mountain-Generated Turbulence Eddies, With Impacts on the Main Bearing: A Validation Study
Previous computational and field experiments identify three characteristic time scales in the aerodynamic responses of utility-scale wind turbine loads to atmospheric boundary layer (ABL) turbulence: a 30-90 second time scale for the passage of high/low speed "streaks" through the rotor plane, the blade and rotor rotation time scales (approximately 1 to 5 seconds), and a sub-second time scale created by blade rotation through gradients within eddy coherent structure. In the current study we compare aerodynamic load responses from daytime ABL turbulence quantified with large-eddy simulation and a actuator line model of the NREL 5 MW wind turbine with analysis of field data from the NREL/GE 1.5 MW wind turbine 5 kilometers east of the Rocky Mountain Front Range in Colorado. In addition, we contrast the responses to the passage of the mountain-generated eddies embedded within the westerly winds with the ABL eddies embedded within northerly/southerly winds. These analyses are in context with the nonsteady forcing of the main bearing by the aerodynamic generation of nontorque bending moments on the main shaft. Potentially relevant to main bearing failure mechanisms, both computational and field data show that the magnitudes of turbulence-generated nontorque bending moments, that we show generate nonsteady force on the main bearing, are of order, and often larger than, torque (which underlies power). However, the temporal variations in these two responses are uncorrelated, implying that the aerodynamic mechanisms that drive power and main bearing response are fundamentally different. We find this to be the case in the field with both mountain-generated eddies (westerly winds) and ABL-generated eddies (northerly/southerly winds). Whereas the time and length scales are comparable, the mountain eddies were somewhat more energetic than the northerly/southerly ABL eddies. Interestingly, however, the fluctuations in nontorque bending moment that force the main bearing were found to be stronger when forced by the ABL eddies than the mountain eddies. The field studies validate the key results from the computational study and show even stronger response in the nontorque bending moment than in the computer simulations. In all cases, the torque and nontorque bending moments are temporally uncorrelated, torque and power are driven by time variations in rotor-averaged horizontal wind velocity and nontorque bending moments are driven by time changes in the degree of nonuniformity in the distribution of velocity over the rotor plane. Thus the results generalize the mechanisms underlying nonsteady aerodynamic forcing to classes of turbulence eddy types with strength of order or stronger than ABL eddies with transverse scale of order the wind turbine rotor. These include atmospheric turbulence eddies, topography-generated turbulence eddies and, by extension, impacts of turbine-wake-scale turbulence eddies on downstream wind turbine rotors.
17 WIND ENERGY↗
Ground Winds Experienced by the Space Launch System Rocket on the Pad before the Artemis I Launch
Over the course of the development of the Space Launch System (SLS) human-rated heavy-lift launch vehicle, the magnitude and nature of the ground winds experienced by the rocket and its Mobile Launcher (ML) on Pad 39B at the NASA Kennedy Space Center (KSC) became a more critical environment that required characterization as well as a more accurate prediction of the vehicle and ML response in the form of detailed wind loads. The numerous reasons for the sensitivity of the launch system to these ground winds and the growing importance of high fidelity rollout and launch pad wind loading estimates are discussed in this article. A description of the wind measurement instrumentation at and around the Launch Complex is provided. A methodology is developed to estimate from these raw anemometer measurements the winds experienced by the rocket and mobile launcher on the launch pad, either in real time or during post-processing. An analysis is then performed and documented on the 121 days worth of wind measurements recorded while the SLS vehicle was secured on the pad during various launch attempts and wet dress rehearsals. This included the occurrence of a tropical storm that evolved into a named hurricane by the time it arrived on Cape Canaveral and hit the vehicle while sitting on the launch pad. Plans for further developments to improve on this predictive capability in preparation for Artemis II are also presented.
Jeremy T Pinier↗
Ground Winds Experienced by the Space Launch System Rocket on the Pad before the Artemis I Launch
Over the course of the development of the Space Launch System (SLS) human-rated heavy-lift launch vehicle, the magnitude and nature of the ground winds experienced by the rocket and its Mobile Launcher (ML) on Pad 39B at the NASA Kennedy Space Center (KSC) became a more critical environment that required characterization as well as a more accurate prediction of the vehicle and ML response in the form of detailed wind loads. The numerous reasons for the sensitivity of the launch system to these ground winds and the growing importance of high fidelity rollout and launch pad wind loading estimates are discussed in this article. A description of the wind measurement instrumentation at and around the Launch Complex is provided. A methodology is developed to estimate from these raw anemometer measurements the winds experienced by the rocket and mobile launcher on the launch pad, either in real time or during post-processing. An analysis is then performed and documented on the 121 days worth of wind measurements recorded while the SLS vehicle was secured on the pad during various launch attempts and wet dress rehearsals. This included the occurrence of a tropical storm that evolved into a named hurricane by the time it arrived on Cape Canaveral and hit the vehicle while sitting on the launch pad. Plans for further developments to improve on this predictive capability in preparation for Artemis II are also presented.
Jeremy T. Pinier↗
NWTC Researchers Field-Test Advanced Control Turbine Systems to Increase Performance, Decrease Structural Loading of Wind Turbines and Plants
Researchers at the National Renewable Energy Laboratory's (NREL's) National Wind Technology Center (NWTC) are studying component controls, including new advanced actuators and sensors, for both conventional turbines as well as wind plants. This research will help develop innovative control strategies that reduce aerodynamic structural loads and improve performance. Structural loads can cause damage that increase maintenance costs and shorten the life of a turbine or wind plant.
17 WIND ENERGY↗
Assessment of Airfoil Property Sensitivity on Wind Turbine Extreme and Fatigue Loads: Preprint
Wind turbines are designed using a set of simulations to determine the structural loads that the turbine could experience. These structural loads can be significant influenced by physical turbine parameters. While significant research and effort has been put into measuring and defining such parameters, limited work has been done to quantify the sensitivity of structural loads to uncertainty in the physical turbine parameters. This paper therefore seeks to assess the sensitivity of different turbine aerodynamic parameters on the resulting ultimate and fatigue loads of the turbine during normal operational conditions. Eighteen different turbine parameters are screened using an Elementary Effects approach with radial points. The results show a high sensitivity of the loads to the blade twist and lift coefficient distributions. To a lesser extent, other turbine parameters that drive loads include the maximum lift coefficient location, blade chord length, and drag coefficient distributions.
17 WIND ENERGY↗
Reliability‐based layout optimization in offshore wind energy systems
Abstract Existing methods for optimizing wind array layouts typically use power or cost objectives and rarely consider reliability‐based objectives. Component and system failure rates, however, are dependent on location‐specific wind conditions, are influenced by array layout and wake interactions, and have a direct and significant impact on capital costs, operational costs, and power production. Although wind power plant models exist that calculate wind loads with sufficient resolution to capture component loading dynamics from wind conditions, they are computationally expensive and thus not suitable for research applications requiring many evaluations, particularly optimization. This study describes the development of computationally efficient, reliability‐based layout optimization methods, enabling us to explore the relationship between component reliability and layout optimization. These methods include the surrogate modeling of the planet bearing life based on varying wind conditions simulated in FAST.Farm and the formulation of reliability‐based objectives based on failure cost and power production models. Through demonstration of this method, we explore how wind conditions, objective functions, and capacity density influence reliability‐based layout optimization. Results indicate that considering reliability alongside power production can reduce failure costs associated with replacement costs and downtime while maintaining or improving power production. Our conclusions highlight the opportunity for wind power plant developers to integrate reliability and operational expenditures alongside performance and capital expenditure objectives in plant design and development to improve plant performance and costs.
17 WIND ENERGY↗
Reflector Technology Development and System Design for Concentrating Solar Power Technologies
Alcoa began this program in March of 2008 with the goal of developing and validating an advanced CSP trough design to lower the levelized cost of energy (LCOE) as compared to existing glass based, space-frame trough technology. In addition to showing a pathway to a significant LCOE reduction, Alcoa also desired to create US jobs to support the emerging CSP industry. Alcoa's objective during Phase I: Concept Feasibility was to provide the DOE with a design approach that demonstrates significant overall system cost savings without sacrificing performance. Phase I consisted of two major tasks; reflector surface development and system concept development. Two specific reflective surface technologies were investigated, silver metallized lamination, and thin film deposition both applied on an aluminum substrate. Alcoa prepared samples; performed test validation internally; and provided samples to the NREL for full-spectrum reflectivity measurements. The final objective was to report reflectivity at t = 0 and the latest durability results as of the completion of Phase 1. The target criteria for reflectance and durability were as follows: (1) initial (t = 0), hemispherical reflectance >93%, (2) initial spectral reflectance >90% for 25-mrad reading and >87% for 7-mrad reading, and (3) predicted 20 year durability of less than 5% optical performance drop. While the results of the reflective development activities were promising, Alcoa was unable to down-select on a reflective technology that met the target criteria. Given the progress and potential of both silver film and thin film technologies, Alcoa continued reflector surface development activities in Phase II. The Phase I concept development activities began with acquiring baseline CSP system information from both CSP Services and the DOE. This information was used as the basis to develop conceptual designs through ideation sessions. The concepts were evaluated based on estimated cost and high-level structural performance. The target criteria for the concept development was to achieve a solar field cost savings of 25%-50% thereby meeting or exceeding the DOE solar field cost savings target of $\$$350/m 2 . After evaluating various structural design approaches, Alcoa down-selected to a monocoque, dubbed Wing Box, design that utilizes the reflective surface as a structural, load carrying member. The cost and performance potential of the Wing Box concept was developed via initial finite element analysis (FEA) and cost modeling. The structural members were sized through material utilization modeling when subjected to representative loading conditions including wind loading. Cost modeling was utilized to refine potential manufacturing techniques that could be employed to manufacture the structural members. Alcoa concluded that an aluminum intensive collector design can achieve significant cost savings without sacrificing performance. Based on the cost saving potential of this Concept Feasibility study, Alcoa recommended further validation of this CSP approach through the execution of Phase II: Design and Prototype Development. Alcoa Phase II objective was to provide the DOE with a validated CSP trough design that demonstrates significant overall system cost savings without sacrificing performance. Phase II consisted of three major tasks; Detail System Design, Prototype Build, and System Validation. Additionally, the reflector surface development that began in Phase I was continued in Phase II. After further development work, Alcoa was unable to develop a reflective technology that demonstrated significant performance or cost benefits compared to commercially available CSP reflective products. After considering other commercially available reflective surfaces, Alcoa selected Alano's MIRO-SUN product for use on the full scale prototype. Although MIRO-SUN has a lower specular reflectivity compared to other options, its durability in terms of handling, cleaning, and long-term reflectivity was deemed the most important attribute to successfully validate Alcoa's advanced trough architecture. To validate the performance of the Wing Box trough, a 6 meter aperture by 14 meter long prototype trough was built. For ease of shipping to and assembly at NREL's test facility, the prototype was fabricated in two half modules and joined along the centerline to create the Wing Box trough. The trough components were designed to achieve high precision of the reflective surface while leveraging high volume manufacturing and assembly techniques.
14 SOLAR ENERGY↗
Structural analysis for a 40-story building
NASTRAN was chosen as the principal analytical tool for structural analysis of the Illinois Center Plaza Hotel Building in Chicago, Illinois. The building is a 40-story, reinforced concrete structure utilizing a monolithic slab-column system. The displacements, member stresses, and foundation loads due to wind load, live load, and dead load were obtained through a series of NASTRAN runs. These analyses and the input technique are described.
Hua, L.↗
The Study of the Relationship between Probabilistic Design and Axiomatic Design Methodology
Structural failure is rarely a "sudden death" type of event, such sudden failures may occur only under abnormal loadings like bomb or gas explosions and very strong earthquakes. In most cases, structures fail due to damage accumulated under normal loadings such as wind loads, dead and live loads. The consequence of cumulative damage will affect the reliability of surviving components and finally causes collapse of the system. The cumulative damage effects on system reliability under time-invariant loadings are of practical interest in structural design and therefore will be investigated in this study. The scope of this study is, however, restricted to the consideration of damage accumulation as the increase in the number of failed components due to the violation of their strength limits.
Onwubiko, Chin-Yere↗
A DNN surrogate unsteady aerodynamic model for wind turbine loads calculations
A recurrent deep-neural network (DNN) surrogate model capable of modeling the unsteady aerodynamic response and dynamic stall behavior of wind turbine blades has been developed and validated for use in engineering design codes. The model is trained using a subset of the oscillating airfoil experiments conducted at the Ohio State University wind tunnel. The predictions from our DNN model show excellent agreement with the measured data and, in all cases, a marked improvement over the state-of-the-art unsteady aerodynamic models. The DNN-based unsteady aerodynamics model was integrated with OpenFAST to perform full-turbine load computations for the NREL-5MW rotor. The largest differences are observed for the inboard stations, particularly in the pitching moment response, when using the new surrogate model compared to the other models available in OpenFAST.
17 WIND ENERGY↗