scholarly journals Demonstration and uncertainty analysis of synchronised scanning lidar measurements of 2D velocity fields in a boundary-layer wind tunnel

2017 ◽  
Author(s):  
Marijn F. van Dooren ◽  
Filippo Campagnolo ◽  
Mikael Sjöholm ◽  
Nikolas Angelou ◽  
Torben Mikkelsen ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Wind Tunnel ◽  
Uncertainty Analysis ◽  
Wind Turbine ◽  
Short Range ◽  
Goodness Of Fit ◽  
Wind Tunnels ◽  
Small Scale ◽  
Lidar Measurement ◽  
Hot Wire

Abstract. This paper combines the currently relevant research methodologies of scaled wind turbine model experiments in wind tunnels with remote-sensing short-range WindScanner lidar measurement technology. The wind tunnel of the Politecnico di Milano was equipped with three wind turbine models and two short-range WindScanner lidars to demonstrate the benefits of synchronised scanning lidars in such experimental surroundings for the first time. The dual-lidar system can provide fully synchronised trajectory scans with sampling time scales ranging from seconds to minutes. First, staring mode measurements were compared to hot-wire probe measurements commonly used in wind tunnels. This yielded goodness of fit coefficients of 0.969 and 0.902 for the 1 Hz averaged u- and v-components of the wind speed, respectively, validating the 2D measurement capability of the lidar scanners. Subsequently, the measurement of wake profiles on a line as well as wake area scans were executed to illustrate the applicability of lidar scanning to measuring small scale wind flow effects. An extensive uncertainty analysis was executed to assess the accuracy of the method. The downsides of lidar with respect to the hot-wire probes are the larger measurement probe volume and the loss of some measurements due to moving blades. In contrast, the benefits are the high flexibility in conducting both point measurements and area scanning, and the fact that remote sensing techniques do not disturb the flow while measuring. The research campaign revealed a high potential for using short-range synchronised scanning lidars to accurately measure small scale flow structures in a wind tunnel, and increased the knowledge about the corresponding uncertainties.

scholarly journals Demonstration and uncertainty analysis of synchronised scanning lidar measurements of 2-D velocity fields in a boundary-layer wind tunnel

2017 ◽  
Vol 2 (1) ◽  
pp. 329-341 ◽  
Author(s):  
Marijn Floris van Dooren ◽  
Filippo Campagnolo ◽  
Mikael Sjöholm ◽  
Nikolas Angelou ◽  
Torben Mikkelsen ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Uncertainty Analysis ◽  
Wind Turbine ◽  
Short Range ◽  
Goodness Of Fit ◽  
Wind Tunnels ◽  
Small Scale ◽  
Measurement Technology ◽  
Lidar Measurement ◽  
Hot Wire

Abstract. This paper combines the research methodologies of scaled wind turbine model experiments in wind tunnels with short-range WindScanner lidar measurement technology. The wind tunnel at the Politecnico di Milano was equipped with three wind turbine models and two short-range WindScanner lidars to demonstrate the benefits of synchronised scanning lidars in such experimental surroundings for the first time. The dual-lidar system can provide fully synchronised trajectory scans with sampling timescales ranging from seconds to minutes. First, staring mode measurements were compared to hot-wire probe measurements commonly used in wind tunnels. This yielded goodness of fit coefficients of 0.969 and 0.902 for the 1 Hz averaged u and v components of the wind speed, respectively, validating the 2-D measurement capability of the lidar scanners. Subsequently, the measurement of wake profiles on a line as well as wake area scans were executed to illustrate the applicability of lidar scanning to the measurement of small-scale wind flow effects. An extensive uncertainty analysis was executed to assess the accuracy of the method. The downsides of lidar with respect to the hot-wire probes are the larger measurement probe volume, which compromises the ability to measure turbulence, and the possible loss of a small part of the measurements due to hard target beam reflection. In contrast, the benefits are the high flexibility in conducting both point measurements and area scanning and the fact that remote sensing techniques do not disturb the flow during measuring. The research campaign revealed a high potential for using short-range synchronised scanning lidars to measure the flow around wind turbines in a wind tunnel and increased the knowledge about the corresponding uncertainties.

scholarly journals Comparison of Different Driving Modes for the Wind Turbine Wake in Wind Tunnels

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1915
Author(s):  
Bingzheng Dou ◽  
Zhanpei Yang ◽  
Michele Guala ◽  
Timing Qu ◽  
Liping Lei ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Farm ◽  
Relevant Information ◽  
Operating Conditions ◽  
Wind Tunnels ◽  
Driving Mode ◽  
Significant Difference ◽  
The Mean ◽  
Turbine Wake

The wake of upstream wind turbine is known to affect the operation of downstream turbines and the overall efficiency of the wind farm. Wind tunnel experiments provide relevant information for understanding and modeling the wake and its dependency on the turbine operating conditions. There are always two main driving modes to operate turbines in a wake experiment: (1) the turbine rotor is driven and controlled by a motor, defined active driving mode; (2) the rotor is driven by the incoming wind and subject to a drag torque, defined passive driving mode. The effect of the varying driving mode on the turbine wake is explored in this study. The mean wake velocities, turbulence intensities, skewness and kurtosis of the velocity time-series estimated from hot-wire anemometry data, were obtained at various downstream locations, in a uniform incoming flow wind tunnel and in an atmospheric boundary layer wind tunnel. The results show that there is not a significant difference in the mean wake velocity between these two driving modes. An acceptable agreement is observed in the comparison of wake turbulence intensity and higher-order statistics in the two wind tunnels.

scholarly journals Aerodynamic Design of a Small-Scale Model of a Vertical Axis Wind Turbine

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1465 ◽  
Author(s):  
Andrés Meana-Fernández ◽  
Jesús Manuel Fernández Oro ◽  
Katia María Argüelles Díaz ◽  
Mónica Galdo-Vega ◽  
Sandra Velarde-Suárez
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Vertical Axis ◽  
Scale Model ◽  
Small Scale ◽  
Wind Tunnel Testing ◽  
Aerodynamic Design ◽  
Vertical Axis Wind Turbine ◽  
Small Scale Model ◽  
Tunnel Testing

Wind tunnel testing of small-scale models is one of the most useful techniques to predict the performance of real-scale applications. In this work, the aerodynamic design and the construction of a small-scale model of a straight-bladed vertical axis wind turbine for wind tunnel testing has been performed. Using a double multiple streamtube model (DMST), different solidity values for the turbine and different airfoil geometries were compared to select the final design. Once an optimal design was selected, a numerical simulation using Computational Fluid Dynamics (CFD) was performed in order to obtain a more precise description of the flow field as well as the performance of the model. Future work will comprise the characterization of the model and the comparison of the experimental and numerical results.

scholarly journals Validation of CFD Predictions of Urban Wind - Developing a Methodology

2021 ◽  
Author(s):  
◽  
Riley Willis
Keyword(s):  
Wind Tunnel ◽  
City Council ◽  
Wind Tunnels ◽  
Small Scale ◽  
Cfd Model ◽  
Validation Process ◽  
Cfd Simulations ◽  
Entire Area ◽  
Cfd Models ◽  
Wind Tunnel Measurements

<p>“Good mental health in a fluid or CFD modeller is always indicated by the presence of a suspicious nature, cynicism and a ‘show me’ attitude. These are not necessarily the best traits for a life mate or a best friend, but they are essential if the integrity of the modelling process is to be maintained.” (Meroney, 2004)  Over the past 50 years, Computational Fluid Dynamics (CFD) computer simulation programs have offered a new method of calculating the wind comfort and safety data for use in pedestrian wind studies. CFD models claim to have some important advantages over wind tunnels; which remain the most common method of wind calculation. While wind tunnels provide measurements of selected points, CFD simulations provide whole-flow field data for the entire area under investigation (Blocken, 2014; Blocken, Stathopoulos, & van Beeck, 2016). Similarly, wind tunnel measurements must consider the similarity requirements involved with testing a model at small scale, while CFD simulations can avoid this as they are conducted at full scale (Ramponi & Blocken, 2012a).  However, CFD simulations can also often be misleading; and they should only be trusted once they can be proven to be accurate. To appease the requirements for this cynical view- referenced in the above quote- proper verification and validation of a model is imperative.  This thesis investigated and tested the current best practice guidelines around CFD model validation, using existing wind tunnel measurements of generic urban arrays. The goal of the research was to determine whether the existing data and guidance around the validation process was sufficient for a consultant user to trust that a CFD model they created was sufficiently accurate to base design decisions from.  The CFD code Autodesk CFD was used to simulate two configurations first tested as wind tunnel models by the Architectural Institute of Japan, and Opus labs in Wellington. The Wellington City Council wind speed criteria were used to determine whether the CFD simulations met the required accuracy criteria for council consent.  Results from the study found that the CFD models could not meet the accuracy criteria. It concluded that while the validation process provided sufficient guidance, there is a lack of available data which is relevant to CFD validation for urban flows.  It was recommended that at least one improved dataset was required, to build a system by which a consultant can identify what the requirements of a CFD model are to provide accurate CFD analysis of the site under investigation. To accommodate the range of sites likely to be present in urban wind studies, it was recommended that the new dataset provided data for a variety of wind flows likely to be found in cities.</p>

The Dust Problem in Hot-Wire Anemometry

1954 ◽  
Vol 4 (1) ◽  
pp. 93-102 ◽  
Author(s):  
D. C. Collis
Keyword(s):  
Wind Tunnel ◽  
Experimental Work ◽  
Fluid Motion ◽  
Rate Of Change ◽  
Closed Circuit ◽  
Wind Tunnels ◽  
Hot Wire ◽  
Hot Wire Anemometry ◽  
Hot Wires ◽  
The Wire

SummaryExperimental work is described showing that a major cause of changes in the calibrations of hot-wire anemometers consists in the precipitation of dust on the upstream surface of the wire during use. A simple means of cleaning the air in closed-circuit wind tunnels is described. The rate of change of calibration due to dust was reduced in the Manchester University Fluid Motion Laboratory by at least a factor of 15, by adequate cleaning of the air and by minimising the amount of interchange between the tunnel air and the atmosphere. It is concluded that where accurate results are required from hot wires used in a wind tunnel, the tunnel should be designed to be dust-free.

Experimental investigation of the performance and wake effect of a small-scale wind turbine in a wind tunnel

Energy ◽  
2019 ◽  
Vol 166 ◽  
pp. 819-833 ◽  
Author(s):  
Bingzheng Dou ◽  
Michele Guala ◽  
Liping Lei ◽  
Pan Zeng
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Small Scale ◽  
Wake Effect

Turbulence reduction by screens

1988 ◽  
Vol 197 ◽  
pp. 139-155 ◽  
Author(s):  
Johan Groth ◽  
Arne V. Johansson
Keyword(s):  
Wind Tunnel ◽  
Reynolds Numbers ◽  
Wind Tunnels ◽  
Small Scale ◽  
Flow Conditions ◽  
Upstream Side ◽  
Turbulence Suppression ◽  
Controlled Flow ◽  
Reduction Effectiveness

Turbulence suppression by use of screens was studied in a small wind tunnel especially designed and built for the purpose. Wide ranges of mesh sizes and wire-diameter Reynolds numbers were covered in the present investigation, enabling the study of sub- and super-critical screens under the same, well-controlled, flow conditions. For the latter type small-scale fluctuations, produced by the screen itself, interact with the incoming turbulence. In the immediate vicinity of the screen the turbulence was found to be highly anisotropic and the intensities were higher than on the upstream side. Downstream of a short initial decay region, where the intensities decrease rapidly, the return to isotropy was found to be much slower than for the unmanipulated turbulence. The latter was generated by a square rod grid, and was shown to become practically isotropic beyond a distance of roughly 20 mesh widths from the grid. The role of the turbulence scales for the overall reduction effectiveness, and for the optimization of screen combinations for application in low-turbulence wind tunnels was studied.

Smart dynamic rotor control using active flaps on a small-scale wind turbine: aeroelastic modeling and comparison with wind tunnel measurements

Wind Energy ◽  
2012 ◽  
pp. n/a-n/a ◽  
Author(s):  
T.K. Barlas ◽  
W. van Wingerden ◽  
A.W. Hulskamp ◽  
G.A. M. van Kuik ◽  
H.E. N. Bersee
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Small Scale ◽  
Wind Tunnel Measurements ◽  
Rotor Control

A Modular Wing-Tail Airplane Configuration for the Educational Wind Tunnel Laboratory

2004 ◽  
Author(s):  
B. Terry Beck
Keyword(s):  
Wind Tunnel ◽  
Rapid Prototyping ◽  
Calibration Procedure ◽  
Aerodynamic Characteristics ◽  
Wind Tunnels ◽  
Small Scale ◽  
Pitching Moment ◽  
Gravity Effects ◽  
Basic Parameters ◽  
Rapid Prototyping System

An innovative modular airplane configuration has been developed for use in small-scale educational wind tunnels. The “airplane” consists of an interchangeable wing and horizontal tail configuration that mounts on a conventional wind tunnel electronic balance (“sting”) to facilitate measurements of normal force, axial force and longitudinal pitching moment. From these basic parameters, the total lift, total drag, and resultant airplane pitching moment can be deduced, along with the location of the aerodynamic center of the total airplane. Using known wing planform and airfoil shapes facilitates comparison of the total airplane aerodynamic characteristics with those predicted from the known characteristics of the separate wing and horizontal tail. In particular, the aerodynamic center of the simplified airplane configuration can be determined, along with the effect that downwash on the tail has on longitudinal stability of the airplane. Included in the paper is a description of the calibration procedure for the modular “sting” mount. This procedure accounts for an offset “line of action” for aerodynamic forces, as well as offset center of gravity effects. In conjunction with this same test setup, an available Rapid Prototyping system has been used to manufacture the test sections (separate wing and tail) for use in the wind tunnel, and in particular, in the modular wing-tail assembly. This provides tremendous flexibility in the types of wing-tail assemblies that can be investigated experimentally using the same module. The relatively inexpensive prototyping procedure also provides the capability for students to design and test their own configurations. Furthermore, the precision manufacturing capability of the Rapid Prototyping system guarantees reliable reproduction of virtually any desired aerodynamic planform and airfoil shape.

Blade Offset and Pitch Effects on a High Solidity Vertical Axis Wind Turbine

2009 ◽  
Vol 33 (3) ◽  
pp. 237-246 ◽  
Author(s):  
Andrzej J. Fiedler ◽  
Stephen Tullis
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Leading Edge ◽  
Vertical Axis ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Data Set ◽  
Naca 0015 ◽  
Base Data

A high solidity, small scale, 2.5m diameter by 3m high Vertical Axis Wind Turbine (VAWT) consisting of three NACA 0015 profile blades, each with a span of 3m and a chord length of 0.4m, was tested in an open-air wind tunnel facility to investigate the effects of preset toe-in and toe-out turbine blade pitch. The effect of blade mount-point offset was also investigated. The results from these tests are presented for a range of tip speed ratios, and compared with an extensive base data set obtained for a nominal wind speed of 10m/s. Results show measured performance decreases of up to 47% for toe-in, and increases of up to 29% for toe-out blade pitch angles, relative to the zero preset pitch case. Also, blade mount-point offset tests indicate decreases in performance as the mount location is moved from mid-chord towards the leading edge, as a result of an inherent toe-in condition. Observations indicate that these performance decreases may be minimized by compensating for the blade mount offset with a toe-out preset pitch. The trends of the preset blade pitch tests agree with those found in literature for much lower solidity turbines.

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