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Aerospace Optimum wind turbine blade design with xfoil

  1. May 10, 2010 #1
    my dessertation topic is optimum wind turbine blade design with xfoil. and the aim of this project is to find a series of airfoil that gives a good efficiency and also how the angle of attack changes with rotation...pls has somebody got an idea about...and also how best can i start this dessertation....

    pls i need help on this...all help will do... thank you
     
  2. jcsd
  3. May 10, 2010 #2
    Usually the best place to start is with a literature review.

    This isn't a PhD dissertation is it?
     
  4. May 10, 2010 #3
    it is an MSC AEROSPACE ENGINEERING DESSERTATION.
     
  5. May 14, 2010 #4

    FlexGunship

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    Gold Member

    Are you talking about variable blade geometry or variable axial geometry?
     
  6. May 14, 2010 #5
    no even the geometry cuz am only optimizing in a 2D form. well am looking into now is how to look up for the typical windspeed and the typical rotational speed of the turbine..
    i read some journal adviced to use the weibull distribution to find the wind speed with respect to the area at which the turbine will be placed... but when i looked the distribution there is proper understanding.

    pls if someone have got any idea on how to find the typical wind speed and rotational speed i will be very much pleased...

    thanks
     
  7. May 14, 2010 #6
    i think your topic is to design a blade,
    1) for that you have to first decide your operating range of the wind turbine means a speceific value of wind speed, it may be assumed or selected for perticuler location on the basis of atmospheric data,
    2) then you also have to fix your rpm of turbine based on the aplication of the wind turbine (for example if it is conected with generator then you have to fix torque and rpm as per generator load where torque helps in finding length by moment calc and rpm helps in getting angle of attack of airfoil at diff location)
    3) Now it will give you a complete picture of diff velocities at diff location of the span. (total incoming air velcity is the vector sumation of the wind speed in axial diraction and the tangential velocity at any location due to rotation)

    so on the basis of these data you can select or design diff airfoil shape for diff location over the blade span that gives you the complete model of the blade
     
  8. May 21, 2010 #7
    thank malay. well i have trying to get the annual(2009) mean wind speed for the calcualtion of the windspeed using linear regression and last weibull distribution..but i cant get the wind speed.

    it hard to come by this information. pls do u have any help. anyway i got a data for 2007 which i found on a previous project. but am tryin to get 2009
     
  9. May 28, 2010 #8
    If I understand what the topic of your dissertation is it's really related to general propeller blade design. There are loads of resources out there on the internet regarding propeller blade design that you can dig up. There should be loads of reports on the NASA Technical Reports Server ( ntrs.nasa.gov ) on the topic.

    In general if you're working with a fixed pitch wind turbine propeller the efficiency of the propeller is a function of propeller advance ratio, thrust coefficient, and power coefficient and there is a combination of the three of these that gives you the highest efficiency for a given propeller. For your case one way you can start the analysis is by determining what you think the advance ratio will generally be given the atmospheric / wind conditions are like for the geographic site you are designing for. Advance Ratio is defined as

    J = V/nd where

    J= advance ratio
    V= velocity
    n= revolutions
    d= prop diameter

    Starting with velocity (wind speed) and revolutions (whatever you need the turbine to turn the generator at) will give you some target constraints you need to start your turbine blade design from.

    Be sure to look into Blade Element Theory as a starting place to model blade geometry to get the right thrust and power coefficients that you want.

    I have no clue if you have to account for wind direction or not which makes a difference on the aerodynamic results, nor if wind turbines are variable pitched or not, etc. Hope that helps!
     
  10. May 28, 2010 #9
    Thanks dtango, for sometime nw I have been looking through the BEM theory it similar to the turbine blade design. But my worry hw to get the average wind for a year. I have got the mean wind speed data of 2008 and I have done all the necessary statistics, graphs and after that I used weibull to find the distribution based on 2 parameters that is K and C. Nw the only thing left is hw to find the average wind speed from the wiebull cuz the design is for a specific site called shropshire. And I need the wind speed to find the Tip speed ratio of the blade..any help will do. thank you very much for all ur support.
     
  11. May 28, 2010 #10
    Hello Ginobee,

    Could you please avoid abbreviating the words you are trying to convey, it is very hard to follow.

    Thanks
     
  12. May 28, 2010 #11
    Pls what word don't u understand so I can write it again...thank you
     
  13. May 28, 2010 #12
    I mean spelling things out, such as Please for Pls.
     
  14. May 28, 2010 #13
    Oh ok yeah u ar right pls means please..
     
  15. May 28, 2010 #14
    Thanks dtango, for sometime nw I have been looking through the BEM theory it similar to the turbine blade design. But my worry hw to get the average wind for a year. I have got the mean wind speed data of 2008 and I have done all the necessary statistics, graphs and after that I used weibull to find the distribution based on 2 parameters that is K and C. Nw the only thing left is hw to find the average wind speed from the wiebull cuz the design is for a specific site called shropshire. And I need the wind speed to find the Tip speed ratio of the blade..any help will do. thank you very much for all ur support.
     
  16. May 28, 2010 #15
    ginobee - see if this helps. You're really asking for statistics help ;).

    http://www.talentfactory.dk/en/tour/wres/weibull.htm

    What they say is to multiply each wind speed interval by it's related probability and then add them all up. That will give you the average wind speed. Cumulative distribution function (CDF) basis of analysis. Someone with a better stats background then me will need to explain. I get all turned around dealing with it ;).
     
    Last edited by a moderator: Apr 25, 2017
  17. May 28, 2010 #16
    Wind Speed (m/s)

    0.5
    1.0
    1.5
    2.1
    2.6
    3.1
    3.6
    4.1
    4.6
    5.1
    5.7
    6.2
    6.7
    7.2
    7.7
    7.8
    8.2
    8.7
    9.3
    9.8
    10.3
    10.8
    11.3
    11.8
    12.3
    12.9
    13.4
    13.9
    14.4
    15.4
    17.0

    this is my wind speed
     
  18. May 28, 2010 #17
    90
    175
    459
    586
    901
    667
    743
    606
    787
    589
    619
    446
    537
    332
    322
    50
    223
    219
    125
    107
    43
    50
    28
    12
    17
    8
    6
    4
    3
    1
    1
    this is the frequency column of the wind speed above
     
  19. May 28, 2010 #18
    Probability Probability(%)

    0.010273973 1.027
    0.019977169 1.998
    0.052397260 5.240
    0.066894977 6.689
    0.102853881 10.285
    0.076141553 7.614
    0.084817352 8.482
    0.069178082 6.918
    0.089840183 8.984
    0.067237443 6.724
    0.070662100 7.066
    0.050913242 5.091
    0.061301370 6.130
    0.037899543 3.790
    0.036757991 3.676
    0.005707763 0.571
    0.025456621 2.546
    0.025000000 2.500
    0.014269406 1.427
    0.012214612 1.221
    0.004908676 0.491
    0.005707763 0.571
    0.003196347 0.320
    0.001369863 0.137
    0.001940639 0.194
    0.000913242 0.091
    0.000684932 0.068
    0.000456621 0.046
    0.000342466 0.034
    0.000114155 0.011
    0.000114155 0.011

    this the probability i found for the above.
     
  20. May 28, 2010 #19
    0.005284932
    0.020552511
    0.080859452
    0.137643105
    0.264540183
    0.235003288
    0.30541032
    0.284681644
    0.41592411
    0.345869406
    0.399834429
    0.31427726
    0.409934521
    0.272937352
    0.283624658
    0.044520548
    0.209518174
    0.21862
    0.132123288
    0.119380731
    0.050500457
    0.061657534
    0.03617242
    0.016207123
    0.023958356
    0.011744292
    0.009160548
    0.006341918
    0.004932603
    0.001761644
    0.001937808

    when i multiplied the speed by it related probability this is what i got therefore the total of this is given as 4.724914612m/s
    please dtango am i right..
     
  21. May 28, 2010 #20
    4.7 m/s looks about right intuitively looking at you wind speed values and their distribution. Someone who's more versed in CDF's and statistics should comment but that value feels about right for the average basis your data and distribution.
     
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