Optimization of wind augmenters for urban power generation

Mapping Intimacies ◽

10.32920/ryerson.14661627 ◽

2021 ◽

Author(s):

Hans Hamm

Keyword(s):

Energy Source ◽

Porous Medium ◽

Wind Turbine ◽

Stream Flow ◽

Power Efficiency ◽

Free Stream ◽

Test Case ◽

High Demand ◽

Momentum Loss ◽

Low Costs

Wind power is the most available renewable energy source to date due to the relatively low costs and advances in the field. Consequently, there is a high demand for innovative wind technology. Furthermore, providing energy near consumers, such as in inner city dwellings and urban settings, provides a more efficient and more reliable energy source. The use of architecture to augment wind energy extraction is still unresolved and the area of research is still in its infancy. The few studies conducted have shown substantial benefits by using buildings to collect wind to increase the power efficiency of wind turbines beyond the Betz limit. This study utilized computational fluid dynamics to analyze building shapes to optimize wind turbine power production. Results indicate an increase in power of up to approximately 4-8 times compared with that for the undisturbed free stream flow. Furthermore, a porous medium was used to simulate the momentum loss due to the presence of the wind turbine. The trends remained similar despite the momentum loss caused by the presence of the wind turbine. The porous medium results showed an increase of power approximately 2-3 times. The study extended the geometry to 3D to support the 2D results. The test case indicated the 3D results had a higher performance in comparison to 2D due to the 3D interactions of the vortex shedding dampening the variance of velocity in the gap region. Furthermore, a certain geometry performs better at different angles of attack providing the optimal geometry will be specifically tailored to the typical wind directions associated with the desired building location.

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Optimization of wind augmenters for urban power generation

10.32920/ryerson.14661627.v1 ◽

2021 ◽

Author(s):

Hans Hamm

Keyword(s):

Energy Source ◽

Porous Medium ◽

Wind Turbine ◽

Stream Flow ◽

Power Efficiency ◽

Free Stream ◽

Test Case ◽

High Demand ◽

Momentum Loss ◽

Low Costs

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Investigating the Level of Fidelity of an Actuator Line Model in Predicting Loads and Deflections of Rotating Blades under Uniform Free-Stream Flow

Applied Sciences ◽

10.3390/app112412097 ◽

2021 ◽

Vol 11 (24) ◽

pp. 12097

Author(s):

Nikos Spyropoulos ◽

George Papadakis ◽

John M. Prospathopoulos ◽

Vasilis A. Riziotis

Keyword(s):

Boundary Layer ◽

Wind Turbine ◽

Stream Flow ◽

Free Stream ◽

Viscous Effects ◽

Complex Flow ◽

Aeroelastic Simulations ◽

Helicopter Main Rotor ◽

Ambient Turbulence ◽

Blade Loads

In this paper, the accuracy of an in-house Actuator Line (AL) model is tested on aeroelastic simulations of a Wind Turbine (WT) rotor and a helicopter Main Rotor (MR) under uniform free-stream flow. For the scope of aeroelastic analyses, the AL model is coupled with an in-house multibody dynamics code in which the blades are modeled as beams. The advantage from the introduction of CFD analysis in rotorcraft aeroelasticity is related to its capability to account in detail for the interaction of the rotor wake with the boundary layer developed on the surrounding bodies. This has proven to be of great importance in order to accurately estimate the aerodynamic forces and thus the corresponding structural loads and deflections of the blades. In wind turbine applications, a good example of the above is the rotor/ground interaction. In helicopter configurations, the interaction of MR with the ground or the fuselage and the interaction of tail rotor with the duct in fenestron configurations are typical examples. Furthermore, CFD aerodynamic analysis is an obvious modeling option in which the above mentioned asset can be combined with the consideration of the mutual interaction of the rotor with the ambient turbulence. A WT rotor operating inside the atmospheric boundary layer under turbulent free-stream flow is such a case. In the paper, AL results are compared against Blade Element Momentum (BEM) and Lifting Line (LL) model results in the case of the WT, whereas LL and measured data are considered in the helicopter cases. Blade loads and deflections are mainly compared as azimuthal variations. In the helicopter MR cases, where comparison is made against experimental data, harmonic analysis of structural loads is shown as well. Overall, AL proves to be as reliable as LL in the canonical cases addressed in this paper in terms of loads and deflections predictions. Therefore, it can be trusted in more complex flow conditions where viscous effects are pronounced.

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EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.22-24.051-058 ◽

2018 ◽

pp. 51-58

Author(s):

B. P. Khozyainov

Keyword(s):

Wind Turbine ◽

Flow Velocity ◽

Wind Power ◽

Wind Turbines ◽

Power Efficiency ◽

Air Flow ◽

Geometrical Parameters ◽

Wind Speeds ◽

Analytical Studies ◽

Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

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Large-Eddy Simulation of Wind Turbine Flows: A New Evaluation of Actuator Disk Models

Energies ◽

10.3390/en14133745 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3745

Author(s):

Tristan Revaz ◽

Fernando Porté-Agel

Keyword(s):

Boundary Layer ◽

Simple Model ◽

Wind Turbine ◽

Wake Flow ◽

Test Case ◽

Flow Solver ◽

Eddy Simulation ◽

Large Eddy ◽

Layer Flow ◽

Advanced Model

Large-eddy simulation (LES) with actuator models has become the state-of-the-art numerical tool to study the complex interaction between the atmospheric boundary layer (ABL) and wind turbines. In this paper, a new evaluation of actuator disk models (ADMs) for LES of wind turbine flows is presented. Several details of the implementation of such models are evaluated based on a test case studied experimentally. In contrast to other test cases used in previous similar studies, the present test case consists of a wind turbine immersed in a realistic turbulent boundary-layer flow, for which accurate data for the turbine, the flow, the thrust and the power are available. It is found that the projection of the forces generated by the turbine into the flow solver grid is crucial for rotor predictions, especially for the power, and less important for the wake flow prediction. In this context, the projection of the forces into the flow solver grid should be as accurate as possible, in order to conserve the consistency between the computed axial velocity and the projected axial force. Also, the projection of the force is found to be much more important in the rotor plane directions than in the streamwise direction. It is found that for the case of a wind turbine immersed in a realistic turbulent boundary-layer flow, the potential spurious numerical oscillations originating from sharp force projections are not harmful to the results. By comparing an advanced model which computes the non-uniform distribution of the turbine forces over the rotor with a simple model which assumes uniform effects of the turbine forces, it is found that both can lead to accurate results for the far wake flow and the thrust and power predictions. However, the comparison shows that the advanced model leads to better results for the near wake flow. In addition, it is found that the simple model overestimates the rotor velocity prediction in comparison to the advanced model. These elements are explained by the lack of local feedback between the axial velocity and the axial force in the simple model. By comparing simulations with and without including the effects of the nacelle and tower, it is found that the consideration of the nacelle and tower is relatively important both for the near wake and the power prediction, due to the shadow effects. The grid resolution is not found to be critical once a reasonable resolution is used, i.e. in the order of 10 grid points along each direction across the rotor. The comparison with the experimental data shows that an accurate prediction of the flow, thrust, and power is possible with a very reasonable computational cost. Overall, the results give important guidelines for the implementation of ADMs for LES.

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Identification of coexisting dynamics in boundary layer flows through proper orthogonal decomposition with weighting matrices

Meccanica ◽

10.1007/s11012-021-01367-7 ◽

2021 ◽

Author(s):

Matteo Dellacasagrande ◽

Dario Barsi ◽

Patrizia Bagnerini ◽

Davide Lengani ◽

Daniele Simoni

Keyword(s):

Experimental Data ◽

Proper Orthogonal Decomposition ◽

Fourier Transforms ◽

Free Stream ◽

Numerical Test ◽

Separated Flow ◽

Orthogonal Decomposition ◽

Inner Product ◽

Test Case ◽

Proper Orthogonal

AbstractA different version of the classic proper orthogonal decomposition (POD) procedure introducing spatial and temporal weighting matrices is proposed. Furthermore, a newly defined non-Euclidean (NE) inner product that retain similarities with the POD is introduced in the paper. The aim is to emphasize fluctuation events localized in spatio-temporal regions with low kinetic energy magnitude, which are not highlighted by the classic POD. The different variants proposed in this work are applied to numerical and experimental data, highlighting analogies and differences with respect to the classic and other normalized variants of POD available in the literature. The numerical test case provides a noise-free environment of the strongly organized vortex shedding behind a cylinder. Conversely, experimental data describing transitional boundary layers are used to test the capability of the procedures in strongly not uniform flows. By-pass and separated flow transition processes developing with high free-stream disturbances have been considered. In both cases streaky structures are expected to interact with other vortical structures (i.e. free-stream vortices in the by-pass case and Kelvin–Helmholtz rolls in the separated type) that carry a significant different amount of energy. Modes obtained by the non-Euclidean POD (NE-POD) procedure (where weighted projections are considered) are shown to better extract low energy events sparse in time and space with respect to modes extracted by other variants. Moreover, NE-POD modes are further decomposed as a combination of Fourier transforms of the related temporal coefficients and the normalized data ensemble to isolate the frequency content of each mode.

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Analysis of Wind Turbine Aging through Operation Data Calibrated by LiDAR Measurement

Energies ◽

10.3390/en14082319 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2319

Author(s):

Hyun-Goo Kim ◽

Jin-Young Kim

Keyword(s):

Power Generation ◽

Wind Speed ◽

Wind Turbine ◽

Wind Farm ◽

Free Stream ◽

Turbine Blades ◽

Wind Farms ◽

Lidar Measurement ◽

Wind Turbine Blades ◽

Wake Effect

This study analyzed the performance decline of wind turbine with age using the SCADA (Supervisory Control And Data Acquisition) data and the short-term in situ LiDAR (Light Detection and Ranging) measurements taken at the Shinan wind farm located on the coast of Bigeumdo Island in the southwestern sea of South Korea. Existing methods have generally attempted to estimate performance aging through long-term trend analysis of a normalized capacity factor in which wind speed variability is calibrated. However, this study proposes a new method using SCADA data for wind farms whose total operation period is short (less than a decade). That is, the trend of power output deficit between predicted and actual power generation was analyzed in order to estimate performance aging, wherein a theoretically predicted level of power generation was calculated by substituting a free stream wind speed projecting to a wind turbine into its power curve. To calibrate a distorted wind speed measurement in a nacelle anemometer caused by the wake effect resulting from the rotation of wind-turbine blades and the shape of the nacelle, the free stream wind speed was measured using LiDAR remote sensing as the reference data; and the nacelle transfer function, which converts nacelle wind speed into free stream wind speed, was derived. A four-year analysis of the Shinan wind farm showed that the rate of performance aging of the wind turbines was estimated to be −0.52%p/year.

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Aspects of Shear Layer Unsteadiness in a Three-Dimensional Supersonic Wake

Journal of Fluids Engineering ◽

10.1115/1.2062727 ◽

2005 ◽

Vol 127 (6) ◽

pp. 1085-1094 ◽

Cited By ~ 4

Author(s):

Alan L. Kastengren ◽

J. Craig Dutton

Keyword(s):

Shear Layer ◽

Stream Flow ◽

Free Stream ◽

Angle Of Attack ◽

Three Dimensional ◽

Base Flow ◽

Recirculation Region ◽

Side View ◽

Near Wake ◽

Supersonic Wake

The near wake of a blunt-base cylinder at 10° angle-of-attack to a Mach 2.46 free-stream flow is visualized at several locations to study unsteady aspects of its structure. In both side-view and end-view images, the shear layer flapping grows monotonically as the shear layer develops, similar to the trends seen in a corresponding axisymmetric supersonic base flow. The interface convolution, a measure of the tortuousness of the shear layer, peaks for side-view and end-view images during recompression. The high convolution for a septum of fluid seen in the middle of the wake indicates that the septum actively entrains fluid from the recirculation region, which helps to explain the low base pressure for this wake compared to that for a corresponding axisymmetric wake.

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