Wind blade chord and twist angle optimization

wumingsheng

This paper shows a method to obtain optimal chord and twist distributions in wind
turbine blades by using genetic algorithms. The distributions are computed to maximize
the mean expected power depending on theWeibull wind distribution at a specific
site because in wind power systems optimization is highly site dependent [1]. This approach
avoids assumptions about optimal attack angle related to the ratio between the
lift to drag coefficients.
Genetic algorithms are global optimizers that have a wide trade-off between exploration
and explotation on the space problem. The geometry definition of a wind
blade is a problem with many degrees of freedom being suitable to fall in local optima,
which can be surpassed using evolutionary methods. Evolutionary Algorithms
are frequently used as powerful optimization methods. They are stochastic methods
inspired in the natural process of evolution[2, 3], and among their advantages are their
global search due to the management of a population of candidate solutions instead
only one, and also the only requirement of the knowledge of the fitness function value
to perform a evolutionary optimization, without any other consideration such as derivability
or continuity of the function. Many different optimum design problems in
multiple fields of sciences and engineering have been solved outperforming any other
previous results with evolutionary algorithms [4].
To optimize chord and twist distributions, an efficient implementation of the Blade-
Element and Momentum(BEM) theory [1, 5, 6] is used. It is basically a simplified
theory that is used routinely by wind power industry because it provides reasonably
accurate prediction of performance. The BEM theory has shown to give good accuracy
with respect to time cost, and at moderate wind speeds, it has sufficed for blade
geometry optimization.
In the implementation of BEM, the sophistication is dismiss to reduce computational
cost. The time required to evaluate the forces in a typical turbine is in the order
of milliseconds, which allows massive evaluation of trial turbines. The implementation
is validated by comparing power prediction with the experimental data of the

Risø test turbine that is one of six experimental turbines widely tested by the IEA. The
data are contained in the Annex XVIII report [7] and in the public database of rotor
performances at the ECN.
High quality in results is obtained until the stall zone, about wind speed of 13m/s
proximately. Predictions are used to compute the mean power that is the fitness function
in the genetic algorithm. The mean power, which is proportional to the annual
generated energy, is obtained by averaging power predictions with the probability obtained
from the Weibull distribution of the specific site. To obtain the optimal blade,
the upper and lower limits of chord and twist are needed as well as an optional upper
limit of the blade area.

大腳丫

引用第17樓lewjane84于2010-02-26 12:12 PM發表的  :
naca
du
ffa

ffa是不是收費的啊？

lewjane84

naca
du
ffa

大腳丫

引用第9樓chnkn于2009-06-06 10:39 AM發表的  :
回到風能領域，有個8 6 3計劃課題，說是要研究我國自主知識產權的風電機組專用翼型族，最后恐怕也是把DU？NREL S或者某個翼型族拿來作作風 洞試 驗了事？等著瞧吧。

請問各位大哥，現在國內主流葉片采用的是什么翼型啊？

大腳丫

看來，這里的都是高人阿！
學習、受教了！呵呵

wumingsheng

陳兄，是的，

目前投資經商環境惡化，民營日子不好過。

但是他們是最有活力，最富創造力的一個群體了。

給了合適的陽光，溫度，就能長出奇跡。

當然，如果人有老毛子那么厲害，我們應早就有了我們自己的暴力美學史了。 [s:2]

chnkn

吳兄，與您看法一致，比較悲觀！

相反，我比較看好民營企業。可是目前的環境，對中小民營企業生存不易啊 [s:6]

wumingsheng

引用第9樓chnkn于2009-06-06 10:39 AM發表的  :
回到風能領域，有個8 6 3計劃課題，說是要研究我國自主知識產權的風電機組專用翼型族，最后恐怕也是把DU？NREL S或者某個翼型族拿來作作風 洞試 驗了事？等著瞧吧。

呵呵，開玩笑說說阿。

自主知識產權？

汽車的自動變速箱還是前不久由吉利汽車拿下來的呢。

從老毛子50年代援建的解放汽車開始，50年，發動機不說了。連個變速箱搞了50多年都沒搞出來。

在8年前，也是所謂地863計劃，賣國債籌資8個多億，搞了400多磚家來搞變速箱，所有的國有精英集合起來，5年后自動放棄，無論怎么拆，怎么模仿，還是搞不清。

然后吉利出來自己搞。搞成了。花點點錢，點點人。

對于國家的研究機構，算了吧。

上上新聞可以，用上場不行。

多少老毛子在中國航空工業？[s:7]

看看長征火箭的發動機是誰的？



運輸我們的洲際導彈的車是誰的？

隨便說說阿[s:7] 比較悲觀。

chnkn

幫我分析一下，上面哪個詞敏感？怎么合一起就發不出來？

chnkn

這個樣子應該不算暴力美學范疇了吧？