Seven-Sensor Fast-Response Probe for Full-Scale Wind Turbine Flowfield Measurements

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
M. Mansour ◽  
G. Kocer ◽  
C. Lenherr ◽  
N. Chokani ◽  
R. S. Abhari
Keyword(s):  
Wind Turbine ◽  
Wind Profile ◽  
Lift Coefficient ◽  
Cost Effective ◽  
Fast Response ◽  
Full Scale ◽  
Site Assessment ◽  
Measured Time ◽  
Wind Profiles ◽  
Logarithmic Height

The unsteady wind profile in the atmospheric boundary layer upstream of a modern wind turbine is measured. The measurements are accomplished using a novel measurement approach that is comprised of an autonomous uninhabited aerial vehicle (UAV) that is equipped with a seven-sensor fast-response aerodynamic probe (F7S-UAV). The autonomous UAV enables high spatial resolution (∼6.3% of rotor diameter) measurements, which hitherto have not been accomplished around full-scale wind turbines. The F7S-UAV probe developed at ETH Zurich is the key-enabling technology for the measurements. The time-averaged wind profile from the F7S-UAV probe is found to be in very good agreement to an independently measured profile using the UAV. This time-averaged profile, which is measured in moderately complex terrain, differs by as much as 30% from the wind profile that is extrapolated from a logarithmic height formula; therefore, the limited utility of extrapolated profiles, which are commonly used in site assessments, is made evident. The time-varying wind profiles show that at a given height, the velocity fluctuations can be as much as 44% of the time-averaged velocity, therefore indicating that there are substantial loads that may impact the fatigue life of the wind turbine’s components. Furthermore, the shear in the velocity profile also subjects the fixed pitch blade to varying incidences and loading. Analysis of the associated velocity triangles indicates that the sectional lift coefficient at midspan of this modern turbine would vary by 12% in the measured time-averaged wind profile. These variations must be accounted in the structural design of the blades. Thus, the measurements of the unsteady wind profile accomplished with this novel measurement system demonstrate that it is a cost effective complement to the suite of available site assessment measurement tools.

Full Scale Wind Turbine Flowfield Measurements Using a 7-Sensor Fast Response Probe

2010 ◽  
Author(s):  
M. Mansour ◽  
G. Kocer ◽  
C. Lenherr ◽  
N. Chokani ◽  
R. S. Abhari
Keyword(s):  
Wind Turbine ◽  
Measurement System ◽  
Wind Profile ◽  
Lift Coefficient ◽  
Cost Effective ◽  
Fast Response ◽  
Turbine Rotor ◽  
Full Scale ◽  
Weight Restrictions ◽  
Measurement Approach

The unsteady wind profile in the atmospheric boundary layer upstream of a modern wind turbine is measured. The measurements are accomplished using a novel measurement approach that is developed and demonstrated for wind energy applications. The measurements of the unsteady 3D velocity field have to be resolved in a low dynamic head environment and over large flow angles around a modern wind turbine (rotor diameter 80–120m and tower height 60–100m). The novel measurement approach is comprised of an autonomous Uninhabited Aerial Vehicle (UAV) that is equipped with a seven-sensor fast-response aerodynamic probe (F7S-UAV). The autonomous UAV enables high spatial resolution (∼9% of rotor diameter) measurements, which hitherto have not been accomplished around full-scale wind turbines. The 7-sensor fast-response aerodynamic probe developed at ETH Zurich is the key-enabling technology for the measurements. This measurement system is realized as a light, compact measurement chain that conforms to the limited payload area and weight restrictions of the UAV. The time-averaged wind profile from the F7S-UAV probe is found to be in very good agreement to an independently measured profile using the UAV. This time-averaged profile, which is measured at a wind turbine that is located in moderately complex terrain, differs by as much as 30% from the wind profile that is extrapolated from a logarithmic height formula; therefore the limited utility of extrapolated profiles, which are commonly used in site assessments, is made evident. The time-varying wind profiles show that, at a given height, the velocity fluctuations can be as much as 44% of the time-averaged velocity, therefore indicating that the wind turbine and its components, notably the gearbox, will experience substantial loads that may impact the fatigue life of the components. Furthermore, the shear in the velocity profile also subjects the fixed pitch blade to varying incidences and loading. Analysis of the associated velocity triangles indicates that the sectional lift coefficient at mid-span of this modern turbine would vary by 12% in the measured time-averaged wind profile. These variations must be accounted in the structural design of the blades. Thus the measurements of the unsteady wind profile accomplished with this novel measurement system, demonstrate that it is a cost effective complement to the suite of available site assessment measurement tools.

scholarly journals Determining the Optimized Hub Height of Wind Turbine Using the Wind Resource Map of South Korea

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2949 ◽  
Author(s):  
Lee ◽  
Kim ◽  
Kang ◽  
Kim
Keyword(s):  
South Korea ◽  
Wind Turbine ◽  
Wind Profile ◽  
Lower Layer ◽  
Economic Feasibility ◽  
Strong Wind ◽  
Cost Of Energy ◽  
Height Increase ◽  
Wind Profiles ◽  
Wind Resource

Although the size of the wind turbine has become larger to improve the economic feasibility of wind power generation, whether increases in rotor diameter and hub height always lead to the optimization of energy cost remains to be seen. This paper proposes an algorithm that calculates the optimized hub height to minimize the cost of energy (COE) using the regional wind profile database. The optimized hub height was determined by identifying the minimum COE after calculating the annual energy production (AEP) and cost increase, according to hub height increase, by using the wind profiles of the wind resource map in South Korea and drawing the COE curve. The optimized hub altitude was calculated as 75~80 m in the inland plain but as 60~70 m in onshore or mountain sites, where the wind profile at the lower layer from the hub height showed relatively strong wind speed than that in inland plain. The AEP loss due to the decrease in hub height was compensated for by increasing the rotor diameter, in which case COE also decreased in the entire region of South Korea. The proposed algorithm of identifying the optimized hub height is expected to serve as a good guideline when determining the hub height according to different geographic regions.

scholarly journals Design and Implementation of a Low Power Wind Turbine Emulator Through the Induction Motor-Permanent Magnet Generator Arrangement

2020 ◽  
Vol 29 (54) ◽  
pp. e10530
Author(s):  
David Felipe Bajonero-Sandoval ◽  
Jeyson Sanabria-Vargas ◽  
César Leonardo Trujillo-Rodriguez
Keyword(s):  
Wind Speed ◽  
Low Power ◽  
Wind Turbine ◽  
Permanent Magnet ◽  
Induction Motor ◽  
Wind Profile ◽  
Labview Software ◽  
Three Phase ◽  
Wind Profiles ◽  
Permanent Magnet Generator

This paper presents the design and construction stage of a low power wind turbine emulator, which is used at the laboratory level, to reproduce different wind profiles. There are several types of wind emulators, among which the wind tunnel emulators stand out. These emulators use a motor with a propeller on their axis to obtain the desired wind speed. However, in the present work -and done from a computer- speed control is developed for a three-phase induction motor, thus driving a permanent magnet generator. The motor-generator group is controlled through a program developed in the Labview software. Also, it has the particularity of operating automatically, being able to load different speed data. Such data is associated with a particular power that takes into account the selected wind profile and can operate through manual control of the wind speed. However, this depends on the frequency given. The emulator operation is validated experimentally through two scenarios: the first one emulates the curve presented by the Eolos turbine and subsequently compares the results obtained, whereas the second one loads the wind profile of Uribía-Guajira -a region in Colombia-  achieving that the emulated wind profile can be accurately seen in the loaded wind profile.

Full-Scale Wind Turbine Near-Wake Measurements Using an Instrumented Uninhabited Aerial Vehicle

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
G. Kocer ◽  
M. Mansour ◽  
N. Chokani ◽  
R.S. Abhari ◽  
M. Müller
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Three Dimensional ◽  
Fast Response ◽  
Full Scale ◽  
Wake Flow ◽  
Near Wake ◽  
Simulation Tools ◽  
Wind Simulation ◽  
Aerial Vehicle

In this paper, the first-ever measurements of the wake of a full-scale wind turbine using an instrumented uninhabited aerial vehicle (UAV) are reported. The key enabler for this novel measurement approach is the integration of fast response aerodynamic probe technology with miniaturized hardware and software for UAVs that enable autonomous UAV operation. The measurements, made to support the development of advanced wind simulation tools, are made in the near-wake (0.5D–3D, where D is rotor diameter) region of a 2 MW wind turbine that is located in a topography of complex terrain and varied vegetation. Downwind of the wind turbine, profiles of the wind speed show that there is strong three-dimensional shear in the near-wake flow. Along the centerline of the wake, the deficit in wind speed is a consequence of wakes from the rotor, nacelle, and tower. By comparison with the profiles away from the centerline, the shadowing effects of nacelle and tower diminish downstream of 2.5D. Away from the centerline, the deficit in wind speed is approximately constant ≈ 25%. However, along the centerline, the deficit is ≈ 65% near to the rotor, 0.5D–1.75D, and only decreases to ≈ 25% downstream of 2.5D.

Wind Profile Effect on Small Wind Turbine Noise Generation

2014 ◽  
Author(s):  
Aki Grönman ◽  
Jari Backman ◽  
Anna Avramenko
Keyword(s):  
Wind Turbine ◽  
Wind Profile ◽  
Three Dimensional ◽  
Ground Surface ◽  
Aerodynamic Noise ◽  
Speed Ratio ◽  
Small Scale ◽  
Noise Generation ◽  
Acoustic Analogy ◽  
Wind Profiles

Small wind turbines are usually located close to buildings, and therefore, the noise generation can be both annoying and a risk for the health. The number of wind turbine installations is growing, and the request for distributed small scale energy production is one of the future trends in the energy market. The wind behavior is usually non-linear close to the ground surface. Especially, small turbines with low nacelle heights have a relatively declined wind profile at the blades. The chosen modeling approach coupled three-dimensional RANS with the Ffowcs Williams-Hawkings acoustic analogy. A series of numerical simulations was performed to study the reliability of the modeling. Three different grids were used to study the grid independency close to the turbine nominal tip to speed ratio. A reasonable agreement in the noise trends was found between the modeling and the measurements and previous studies. This encouraged us to study three different wind profiles with a down scaled wind turbine model. The results indicate that the aerodynamic noise of small turbines is not markedly affected by the wind profile.

Full‐scale shake‐table tests on two unreinforced masonry cavity‐wall buildings: effect of an innovative timber retrofit

2021 ◽  
Author(s):  
Marco Miglietta ◽  
Nicolò Damiani ◽  
Gabriele Guerrini ◽  
Francesco Graziotti
Keyword(s):  
Seismic Vulnerability ◽  
Concrete Slab ◽  
Cost Effective ◽  
Unreinforced Masonry ◽  
Full Scale ◽  
Cavity Wall ◽  
Masonry Walls ◽  
Shake Table ◽  
Earthquake Excitation ◽  
Reinforced Concrete Slab

AbstractTwo full-scale building specimens were tested on the shake-table at the EUCENTRE Foundation laboratories in Pavia (Italy), to assess the effectiveness of an innovative timber retrofit solution, within a comprehensive research campaign on the seismic vulnerability of existing Dutch unreinforced masonry structures. The buildings represented the end-unit of a two-storey terraced house typical of the North-Eastern Netherlands, a region affected by induced seismicity over the last few decades. This building typology is particularly vulnerable to earthquake excitation due to lack of seismic details and irregular distribution of large openings in masonry walls. Both specimens were built with the same geometry. Their structural system consisted of cavity walls, with interior load-bearing calcium-silicate leaf and exterior clay veneer, and included a first-floor reinforced concrete slab, a second-floor timber framing, and a roof timber structure supported by masonry gables. A timber retrofit was designed and installed inside the second specimen, providing an innovative sustainable, light-weight, reversible, and cost-effective technique, which could be extensively applied to actual buildings. Timber frames were connected to the interior surface of the masonry walls and completed by oriented strands boards nailed to them. The second-floor timber diaphragm was stiffened and strengthened by a layer of oriented-strand boards, nailed to the existing joists and to additional blocking elements through the existing planks. These interventions resulted also in improved wall-to-diaphragm connections with the inner leaf at both floors, while steel ties were added between the cavity-wall leaves. The application of the retrofit system favored a global response of the building with increased lateral capacities of the masonry walls. This paper describes in detail the bare and retrofitted specimens, compares the experimental results obtained through similar incremental dynamic shake-table test protocols up to near-collapse conditions, and identifies damage states and damage limits associated with displacements and deformations.

Experimental investigations of flow over NACA airfoils 0021 and 4412 of wind turbine blades with and without Tubercles

2021 ◽  
pp. 0309524X2110071
Author(s):  
Usman Butt ◽  
Shafqat Hussain ◽  
Stephan Schacht ◽  
Uwe Ritschel
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Wind Turbine ◽  
Critical Region ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Experimental Investigations ◽  
Wind Turbine Blades

Experimental investigations of wind turbine blades having NACA airfoils 0021 and 4412 with and without tubercles on the leading edge have been performed in a wind tunnel. It was found that the lift coefficient of the airfoil 0021 with tubercles was higher at Re = 1.2×105 and 1.69×105 in post critical region (at higher angle of attach) than airfoils without tubercles but this difference relatively diminished at higher Reynolds numbers and beyond indicating that there is no effect on the lift coefficients of airfoils with tubercles at higher Reynolds numbers whereas drag coefficient remains unchanged. It is noted that at Re = 1.69×105, the lift coefficient of airfoil without tubercles drops from 0.96 to 0.42 as the angle of attack increases from 15° to 20° which is about 56% and the corresponding values of lift coefficient for airfoil with tubercles are 0.86 and 0.7 at respective angles with18% drop.

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