Wind Engineering - Science topic

Based on your final statement it appears that you are already monitoring the power to your sensors and instrumentation. However, a simple amp-meter on the input to the electronics package would work.

The best way to reduce the power consumption is to first eliminate any sensor, and it's related instrumentation, that is not strictly required for your project. The next step would be to evaluate the sensors to determine if they are the most energy efficient type available. Finally, analyze your instrumentation to eliminate any redundancy. For example, if one sensor has a power supply of 5 watts but only requires 3 watts to operate and a second sensor has a power supply of 7 watts but only requires 4 watts to operate. You may be able to eliminate the first power supply and use the second to power both. This reduces the overall power consumption because a power supply rated at 5 watts will actually consume 6 or 7 watts due to internal resistances and parasitic losses in transformers.

The phenomenon in the difference in pile settlement along the length is typical for long piles. Especially this phenomenon occurs in long bored piles.

Integral length scales can arise from both Eulerian and Lagrangian autocorrelation functions and both are useful and both can be negative in at least some regions. If, on average, a velocity perturbation at one point or residence time is negative when the perturbation at the initial point is positive, the perturbations are negatively correlated and the autocorrelation function is negative valued at that point/time. If this persists far/long enough, the integral of the function can become negative. This is not common but is routinely observed in flows, especially those that have coherent structures. It is common that people use exponential decay functions to approximate the autocorrelation functions, and there is some theoretical basis for this. However, complex flows have much more complex autocorrelation functions. You may be being misled by the common practice of using such functions to approximate what can be a more complex function. The exponential decay function, by the way, cannot be entirely accurate since its derivative at initial condition is not zero. Since flows have mass/momentum, their autocorrelation functions should have a zero derivative in the limit of zero distance/time from the origin.

Having said all that, I suspect there is an error in your data analysis.

WindFarmer is proprietary and costs around 5000 Euros per year. Not Open source, nor free

Dear Bassam:

At the first, and as you know that several different factors influence the potential wind resource in an area. The three main factors that influence power output are: wind speed, air density, and blade radius. Wind turbines need to be in areas with a lot of wind on a regular basis, which is more important than having occasional high winds.

# Wind speed:

Wind speed largely determines the amount of electricity generated by a turbine. Higher wind speeds generate more power because stronger winds allow the blades to rotate faster. Faster rotation translates to more mechanical power and more electrical power from the generator. The relationship between wind speed and power for a typical wind turbine is shown in Figure (a).

Turbines are designed to operate within a specific range of wind speeds. The limits of the range are known as the cut-in speed and cut-out speed. The cut-in speed is the point at which the wind turbine is able to generate power. Between the cut-in speed and the rated speed, where the maximum output is reached, the power output will increase cubically with wind speed. For example, if wind speed doubles, the power output will increase 8 times. This cubic relationship is what makes wind speed such an important factor for wind power. This cubic dependence does cut out at the rated wind speed. This leads to the relatively flat part of the curve in Figure (a), so the cubic dependence is during the speeds below 15 m/s (54 kph).

The cut-out speed is the point at which the turbine must be shut down to avoid damage to the equipment. The cut-in and cut-out speeds are related to the turbine design and size and are decided on prior to construction.

#Air Density:

Power output is related to the local air density, which is a function of altitude, pressure, and temperature. Dense air exerts more pressure on the rotors, which results in higher power output.

#Turbine Design:

Wind turbines are designed to maximize the rotor blade radius to maximize power output. Larger blades allow the turbine to capture more of the kinetic energy of the wind by moving more air through the rotors. However, larger blades require more space and higher wind speeds to operate. As a general rule, turbines are spaced out at four times the rotor diameter. This distance is necessary to avoid interference between turbines, which decreases the power output.

# There's a phenomenon, which referred to as the reduced wake effect:

During curtailment, less power is extracted from the wind and thus the wake effects are reduced. This leads to a wind speed increase at the downstream turbine and therefore to an apparent increase of its available power. This phenomenon is referred to as the reduced wake effect.

# So you could benefit from this valuable article about this topic:

"Analysis of the reduced wake effect for available wind power calculation during curtailment"

# Abstract:

With the increase of installed wind power capacity, the contribution of wind power curtailment to power balancing becomes more relevant. Determining the available power during curtailment at the wind farm level is not trivial, as curtailment changes the wake effects in a wind farm. Current best practice to estimate the available power is to sum the available power calculated by every wind turbine. However, during curtailment the changed local wind conditions at the wind turbines lead to inaccurate results at the wind farm level. This paper presents an algorithm to determine the available power of a wind farm during curtailment. Moreover, results of curtailment experiments are discussed that were performed on nearshore wind farm Westermeerwind to validate the algorithm. For the case where a single turbine is being curtailed, it is shown that the algorithm reduces the estimation error for the first downstream turbine significantly. Further development of the algorithm is required for accurate estimation of the second turbine. All further downstream turbines did not experience a change in wake conditions.

I hope it will be helpful ...

With my best regards ...

We are using turbulent air jets which need low air flow whil are rotating the leaves and cover all of them on both sides agmanor@ airgreen.co.il

The main difference between the two loads lie in the prediction of their occurrence. While wind loads could be predicted with much accuracy(including the time of occurrence & intensity levels), unfortunately we have not yet developed any methodologies that enable prediction of time-specific or intensity specific occurrence of earthquakes at a site. Only probabilistic seismic hazard analyses (PSHA) are undertaken for better prediction of earthquake occurrence.

Secondly it is highly uneconomical and impractical to design a structure to remain elastic for a highly uncertain event such as earthquake. Therefore, the ductility of the structure is called for( by introducing R factor) while designing the structure for a much lower level of earthquake. Further it shall be noted that during earthquakes, structures are permitted to undergo different damage states depending on the return periods of the earthquake event.

As elaborated in a 2014 US patent for Artificial Wind Generator:

Ahmet Emre Onay, You can click any location and select the data type (Hourly, daily etc.), select dates, then click process, download result. this will give 10m height data, use power law or logarithmic law to convert to 50 m. Also, you can check Global wind atlas

Dear Prasenjit Sanyal

Try this book https://books.google.com.ua/books?hl=ru&lr=&id=nUHWDwAAQBAJ&oi=fnd&pg=PR11&dq=wind+tunnel&ots=LwHmhX27Xx&sig=FoSoHM6daPPoys2R92pMnkpecQw&redir_esc=y#v=onepage&q=wind%20tunnel&f=false

Barlow, Jewel B., William H. Rae, and Alan Pope. Low-speed wind tunnel testing. John Wiley & Sons, 1999.

Regards

Mr.Prasenjit, i feel for correcting your problem it is better to go with smaller size element with fine mesh. Also, your problem could be corrected with aspect ratio 1, many researchers mentioned that aspect ratio 1 would give better results with close converging with exact results. I mean to say instead of refining longer or shorter direction it is better to use length to width ratio of element is 1 for getting close results..ok all the best in your research..

The new study indicates that large natural climate cycles are a potential culprit.

Using models to study factors that influence global wind behavior, researchers have found that large climate patterns - which affect temperatures in certain parts of the world - have a major impact on wind speed. Temperature differences between adjacent areas, or between the ocean and adjacent land areas, can affect air flow.

You can also read this file below:

1- https://www.scientificamerican.com/article/the-worlds-winds-are-speeding-up/

2- https://www.sciencedirect.com/science/article/abs/pii/S1364032119303259

to estimate wind speed based on the environmental specifications, can also read this file below:

file:///C:/Users/dell/Downloads/atmosphere-10-00804.pdf

file:///C:/Users/dell/Downloads/applsci-09-05385-v2%20(1).pdf

Wind energy is used to generate environmentally friendly electrical energy with high moment forces through the wind turbine rotation. Although electric power generation is good, wind turbine noise affects the environment by creating different sound pressure levels.

1- https://www.tandfonline.com/doi/abs/10.1080/01430750.2020.1720806?journalCode=taen20

2- https://www.simscale.com/blog/2019/09/wind-turbine-blade-design/

3- http://www.ijrar.org/papers/IJRAR19J1380.pdf

You need to keep track of friends and students who are studying in Australia. They usually work on data from neighboring countries.

This is an empirical equation, there is no derivation.

It is usually used by designers to estimate the wind load.

Hello, try to save the txt file as excel format.

Dear Vignesh, depending on what you want to measure, but I think you should use as characteristic length the width of the building or its dimensions in the main direction of motion of the flow.

Let me add the following information FYI: the validity of wind tunnel results obtained in testing of scale models is based on the fluid mechanics Principle of Dynamic Similarity (White, F.M., Fluid Mechanics, 6 ed., Boston, USA: McGraw-Hill, 2003, p. 866) which states that: "If two physical phenomena can be described using the same formulation (same equations and same initial and boundary conditions), the solutions for one of the phenomena are valid for the other one." For the motion of air around and obstacle, this Principle guarantees that the non-dimensional results measured in a wind tunnel for a scale model (e.g., lift, drag, and pitching moment coefficients) will be the same as for the real, full-scale obstacle if the following conditions are fulfilled:

For CFD, this is not usually a problem, since you have much flexibility in defining the boundary conditions and other settings such that these 4 conditions are satisfied and, for example, Re and M match those of the real fluid problem.

Now the dilemma comes when trying to extrapolate wind tunnel results to the real fluid problem: If the fluid properties for both the tests and real case are the same (i.e., same speed of sound (T), ρ and μ), and the scale model is smaller or larger than the real obstacle, it is obvious that it is not possible to have simultaneously the same M and Re as in the real problem. If we cannot replicate simultaneously both parameters, it is then necessary to choose which one will be kept similar to the real case. Generally, we choose the parameter with a stronger influence on the flow. For instance, roughly speaking M is dominant for supersonic flows and Re for subsonic flows (your case). Thus, for example, in high-subsonic testing, we would strive to work with the same Re as in the real case, and would not pay so much attention to M. Effectively, this means that we are not complying fully with the requirements of the Principle of Dynamic Similarity, and thus the test results have some error respect to the behavior in the real case. Many researchers have characterized the Re and M scaling effects to be able to correct for this error when extrapolating the wind tunnel results to the real case, if the Re and/or M in the tunnel are different than those of the real case.

If the fluid properties for both your tests and real case are the same, you should try to work with a model as similar as possible in dimensions the real obstacle, bearing in mind also these recommendations (Barlow, J.B., Rae, W.H., Pope, A., Low-speed Wind Tunnel Testing, 3 ed., NY, USA: Wiley & Sons, 1999, p. 713):

If you manage to have same Re and M, then the lift and drag coefficients (cL = Lift/(0.5*rho*V^2*S) and cD = Drag/(0.5*rho*V^2*S)) that you obtain from the tunnel can be extrapolated to the real vehicle. If you manage to have only the same Re, the lift and drag coefficients that you obtain should be corrected, but this error should not be very large and maybe the values from the tunnel are still valid to you. If you don't manage to have the same Re, then you could correct the cL and cD following the procedure described in the attached image from White's book Fluid Mechanics, for which you need to have values of cL or cD at several flow velocities (i.e., at several Reynolds numbers).

see( https://stackoverflow.com/questions/21484558/how-to-calculate-wind-direction-from-u-and-v-wind-components-in-r )

I think Anays Rigid Dynamics will give you all the possible options in comparison to any other tool. Try for it to cross verify the results.

Dear Amin,

I was also going to suggest you to use QBlade. QBlade is open source software for design and simulation of horizontal and vertical axis wind turbines (HAWT and VAWT), distributed under the GNU General Public License.

What is most interesting to you is that its integration in XFOIL allows airfoil design and airfoil performance analysis, and even allows also for extrapolation of airfoil performance data to 360° angle of attack, etc. That is, QBlade, using panel methods, allows obtaining for any given airfoil the lift and drag coefficients for different angles of attack and values of Re. You can download QBlade and manuals here: http://qblade.npage.de/

If the specific airfoil that you want to test is not available in QBlade's airfoil library/database, in the following UIUC's link you can find the airfoil coordinates to import to QBlade: http://m-selig.ae.illinois.edu/ads.html

Hope this is useful,

Jose

Hi Ahmed, renewable energy is a type of energy which is inexhaustible, while energy efficiency deals with utilising the existing energy irrespective of renewable or non renewable, judiciously. that is, getting the work done with less expenditure of energy without the loss of quality. For example a bulb that draws 3W of power to light a room compared to the similar bulb that draws 5W power to light the same room, is considered to be energy efficient. further if the same bulb utilises electricity obtained from fossil fuel, it is considered to be energy from non renewable source. If the same power is obtained from water or wind energy thn it is energy from renewable source.

hope it helps!! :/

Thank you Leighton Cochran

thank you Leighton Cochran

Khaled. Yes, the buildings and structures you mention (and many other human constructions) are routinely studied in wind tunnels every day. Some at universities (eg UWO, CSU, TTU, UF, Monash, HKUST, etc.) and some at commercial facilities (eg RWDI, CPP, MEL, etc.). The success at modeling various actions on a small-scale model in the wind tunnel has been well-established and refined since the 1960s. There are dozens of wind-engineering societies and associations in many countries around the world (AAWE and AWES to name two I belong to) and these are all connected to the international body, IAWE. The best assessment of "accuracy" is to compare the wind tunnel with a full-scale building in the real wind. There are several good examples of this (a well-known recent example was the Texas Tech University Building that spanned work over the 1990s and 2000s, and an earlier effort in Britain called SILSOE) in the literature and, with some caveats, the agreement is really quite good between model and full scale data. The Elsevier journal called Journal of Wind Engineering and Industrial Aerodynamics has been the source of many papers in this field for over 40 years. Lots of reading for you!

Thank you very much professor Giorgio Soave for the helpful comment, truly the very proper word for the direction of the wind is prevailing direction. As for the foundation, and more specifically the concrete itself which measures could be recommended?

thank you Hayrani Oz

Please check reference below.. hope it will be helpful for you… Regards…

Off course, most limiting factor for installation and use of wind turbine is the wind speed available in the particular area. The decision about the installation of wind turbine is taken on the basis of mean or average wind speed of the particular area. The rated wind speed is considered as 1.4 times of the annual speed for the wind turbine design. The region with annual wind speed with 5 m/s or more is suitable for wind turbine installation.

The most sensitive of the Microswitch pressure transducers (sealed, plastic, robust device about 50x25x12 mm in size with two pressure ports) are inexpensive and at very linear in the calibration in terms of Pa/V. From memory around 100 Pa/v when you calibrate with screw-driven syringe, or similar. Good luck. LC.

Rajasekarababu,

In most of one phase industrial applications, RANS is a pragmatic choice. This is explained by the robustness, ease of use and efficiency of the RANS.

However most of multiphase flows are highly transient and steady state approach does not work.

Some industrial applications expose limitations to the RANS modelling approach. For these applications, LES and DES provide a viable alternative at the expense of increased complexity and simulation time.

Regards

Your first equation is correct. You may refer to the following relevant sources to the LCOE calculations, and its estimation for wind, and solar-PV energy sources. Good luck

I would look on line for the Strouhal number of similar structures at similar Reynolds numbers to see what is already been done. When in doubt 0.22 is a good first guess at the Strouhal number. From there I would set up an excel spreadsheet with different heights above the base plane, then do a 1/7th power law for the boundary layer effect and calculate the wind velocity in 10 or so different points up the height. From there you should be able to get the vortex shedding frequency as a function of wind speed and height to compare to your structural resonances. Figuring out the unsteady lift force is more problematic from first principles but I bet there is a lot out there in the published technical literature. Good luck

Generally there are two approaches for calculating wind pressure: Static approach and dynamic approach. The dynamic approach is more realistic , so it is preferred for any type of structures. Consequently, the dynamic approach is also preferred for towers.

Hello,

I agree with Tony Maine that failures always have non-zero probabilities; however, they can be reduced. There are several ways for achieving that target, such as,

1. Condition, and diagnostic-based monitoring,

2. Preventive maintenance,

3. Enhancing the maintainability of the systems through better designs, sufficient logistics, and technical training.

4. Careful selection of protective devices and subsystems and proper setting of their operation constraints.

5. Oversizing and redundancy of components.

Of course, the reliability is accompanied with costs and so the failure. Therefore, optimal techno-economic reliability level should be determined. There are some relevant publications in my RG profile. Please feel free to read them.

Dear Mehdi,

Could you please explain about how you could come up with "4 percent"?

Hello,

The RETSCreen software includes one of the most complete, and continuously updated database of renewable energy products including wind turbine generators of various scales.

Dear Ali,

Regarding your question, I am attaching a document (even in french) in which it is shown the number ob blades impact on the power coefficient (Cp - left figure)) and the Yaw Moment (right figure) of a wind or marine turbine. When analyzing these curves, it came obvious that a three-blade turbine is the best choice in terms of Cp (even reduced but with a larger TSR range) and Yaw Moment (less oscillations of the turbine pile).

Regards,

Mohamed

My Thanks to you was long pending...Thank you!

Dear Divye Malik

you can put the following steps:

1- the turbulent intensity at the entrance about 0.05 and make a long entrance region, you can read the following papers;

2- make a long entrance region and  you can read the following papers;

3- make the upper and lower boundaries as symmetry.you can read the following papers;

you can read the following papers;

Yes, I know the  synchronous generator wind turbine theoretically and practically well, because also I have treated with it in my PhD when I have designed new Electric Rotary Converter Machine. You can follow and read my published papers in my profile in Google Scholar (Khalid G. Mohammed). My regards

Dr. Khalid G. Mohammed

University of Diyala, College of Engineering, Iraq

Aug.14, 2017

I can also recommend using MERRA-2 which is available here: http://www.soda-pro.com/web-services/meteo-data/merra

The platform itself is very user-friendly and works quite fast.  

Please see the following paper: 

Good luck

Dear Abhishek,

Ingo is right. Just let me add the following to his explanations: The validity of wind tunnel results obtained in testing of scale models is based on the fluid mechanics Principle of Dynamic Similarity [1] which states the following: "If two physical phenomena can be described using the same formulation (same equations and same initial and boundary conditions), the solutions for one of the phenomena are valid for the other one."

For the motion of air around and obstacle, this Principle guarantees that the non-dimensional results measured in a wind tunnel for a scale model will be the same as for the real, full-scale obstacle if the following conditions are fulfilled:

And here is the big Dilemma: If the fluid properties for both the tests and real case are the same (i.e., same speed of sound (T), ρ and μ), and the scale model is smaller or larger than the real obstacle, it is obvious that it is not possible to have simultaneously the same M and Re as in the real problem. If we cannot replicate simultaneously both parameters, it is then necessary to choose which one will be kept similar to the real case. Generally, we choose the parameter with a stronger influence on the flow. For instance, roughly speaking M is dominant for supersonic flows (meaning that the value of M has a stronger effect on the behavior of supersonic flows than the value of Re) and Re for subsonic flows. Thus, for example, in high-subsonic testing, we would strive to work with the same Re as in the real case, and would not pay so much attention to M.

Effectively, this means that we are not complying fully with the requirements of the Principle of Dynamic Similarity. Fortunately, still the wind tunnel results can be useful. The only issue is that they have some error respect to the behavior in the real case, and we have to correct for that. Many researchers have characterized the Re and M scaling effects to be able to correct for this error when extrapolating the wind tunnel results to the real case. So, if the fluid properties for both your tests and real case are the same, you should try to work with a model as similar as possible in dimensions the real obstacle, bearing in mind also these recommendations [2]:

Hope this is useful,

Jose

[1]  White, F.M., Fluid Mechanics, 6 ed., Boston, USA: McGraw-Hill, 2003, p. 866

[2]  Barlow, J.B., Rae, W.H., Pope, A., Low-speed Wind Tunnel Testing, 3 ed., NY, USA: Wiley & Sons, 1999, p. 713

The following link is presenting time history of wind pressures on tall building:

In the base region about 20% of the blade is usually a torque moment large enough and the value of force lift is small, so it is very difficult to get unlimited power in the root of the blade.

Amin- You are right. You may use free wind speed if you are working on large Reynolds number. However, technically, you should be using relative wind speed, especially for small wind turbines. Thanks and best

Thanks and best wishes

The cycloidal propeller StECon works as well horizontal as vertical, because it truns completly under water. The first project StEwaKorad concludes a vertical construction with a gaer outside the water. Now we discuss for a gear filled with water for grease.

The StECon will run also in the wind, but we are looking first for an application in water.

In comparison to an Darrieus-Propeller the blades of the StECon turn arround their own axis and therefore the gear is necessary.

If you are interested have look at www.stecon.xyz and let me know more questions.

Betz limit gives the maximum theoretical output power of wind turbine Cp=0.59. The popular method for finding chord and twist angle of turbine blades is BEM (Blade element momentum) theory with rotor tip and root corrections.  

Many thanks Seghiour

Try to google it, You will find many papers and articles

regards.

Thanks you dear Itsuya Muta sir and all,

I am very thankful to you and above all who has paid their kind attention to this question

Dear sir

I my page please find paper exergy analysis and optimization of wind turbine. I hope it can be helpful

Any fortran code for wavelet analysis?

Hi Verez,

I am already using Emetor. The other sources given by you also very useful. Thanks a lot!!

Given all other parameters being the same, the horizontal axis wind turbines cause less vibrational loads and torque on the tower compared to the vertical axis wind turbines. 

I think this is a testimonial that the horizontal axis wind turbines have the largest market share compared to the vertical axis wind turbines.

Hope this helps answer your question.

Professor Yehia Khalil, Yale University, USA

Fellow of the University of Oxford, UK

It may be of no use to find out that solar and wind energy resources complement each other on a monthly basis - as most weather data are offered. You have to perform simulations in order to know the real situation of the hybrid plant. It does not help much to have simultaneity of wind and solar resources if your storage capacity is dimensioned for one of the sources only; it does not help if there are too long gaps in the availability along time, so that your storage capacity is not big enough, either. I do not believe in such a graphical representation.

Dear Idrisi,

For WInd turbine model, you can find such model in the Matlab simulink demo.

Also you can find some examples for the DFIG in MAtlab DEMO.

for more details please check the following

PMSG are best suited for low-speed and also low-power wind turbine applications.

As you say, it is a small World. I know all those and have worked with them all, some more than others

BR

Søren

Thank you Vinicius Dadalto for your help.

In fact, I worked on the “Robust control by sliding mode of wind turbine based on Doubly-fed Induction Generator” on my M.S work. And now, I continue my PhD work in the same road, i.e. modeling and control of doubly fed induction-generator (DFIG) based on the wind turbine systems. Currently I want to control the MPPT and the pitch angle by fuzzy logic. I need your help if you can. Can you give me your mail please?

Best regards.

Link above was truncated:

Hi all,

I thinks this is good reference for my question. Hope it could be useful for others with the same question.

Mr Bhupendra and Mr Mohamed,

Thank you very much for your help!

Mr Mohamed, I'll study these papers sir. Thank you very much.

Regards

Vinícius

Hi,

Usually using "C_m" in fluent is a good choice.(Torque coefficient)

You can active "C_m" in fluent (in monitors) and by using:

C_p=C_m*TSR

calculate power coefficient.

It's very important that using correct reference values in fluent.

Can you look at the pressure contours near the blades? And the velocity vectors? You should be able to estimate the angle of attack from the vectors and see if the pressure contours make sense according to experiments on airfoils (highly documented)

Dear Ahmed,

I suggest to you a links and attached files in topics.

-Offshore floating vertical axis wind turbines: Advantages ...

https://www.researchgate.net/.../235963001_Offshore_floating_vertical_axis_wind_tu...

-Dr Lin Wang Research Fellow in Structural Mechanics

-15.1 - ijssst

Best regards