求教：為什么阻力型風力機不適用于發電？

一只想飛的貓

兩個問題：
1/幾乎所有的有關風力發電的書都說：“阻力型風力機不適用于發電？”這是為什么？
  B- n+ N8 J( M4 C$ K# V2/為什么書上說垂直軸風力機的風能利用率不如水平軸風力機？垂直軸風力機的風能利用率怎么計算？
; p! B/ T% {/ C求教啦，先謝謝啦。

過街蛤蟆

大蝦的閑情逸致令在下佩服，肯定不象我等為生計而奔波的家伙，

閣下的第一個問題，這是一個數學問題，從數學模型看，效率在15%，這是計算結果，實際要小一些，

第二個問題，你說的這個是依據水平軸的計算公式算的，它葉尖的比速小，算出的結果就小，現在垂直軸有自己的公式計算，同樣是垂直軸，衍生出一批派生系列，有些和水平軸的速度差不多，小也小不多，

, L/ Q% d% i" w% u& E4 W, y阿拉奔波生計，空氣動力學的東西也忘的差不多了，大蝦有空看看新理論，現在的理論很多，尤其是垂直軸的，

一只想飛的貓

過街兄過譽了。幾十年得來的退休銀子是給喝粥的，要想吃肉還得再奔。到機械社區來，得過街兄教誨受益匪淺呀，先謝謝啦。

耀子

垂直軸的技術相對來說還不成熟

KCXD-七刀

Henry duPont of Lorax Energy Systems in Block Island, Rhode Island, dropped by electronically to  enlighten us on the matter of vertical versus horizontal axis wind turbines (VAWT versus HAWT).
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' u, V" y. f5 y+ z% f9 @Henry says the advantages of the VAWT configuration (like the Quietrevolution elsewhere in the Wind Power section ) are that the generator and gearbox can be housed on the ground, and even some distance away from that turbine; and that a VAWT is omnidirectional and requires no yaw mechanism.


The disadvantages of typical VAWT systems are that they usually operate near the ground where there's not much wind; they produce wavy (sinusoidal) power pulses to drive mechanism; they don't start themselves in a breeze; and repair of the main bearing usually means having to take the whole machine apart. (The Quietrevolution appears to solve at least the first problem by being mount ed on a tower.) Most importantly, the VAWT is typically about 40% less efficient than the HAWT in energy production. According to Henry, you would need a VAWT almost twice the size of a HAWT to get the same amount of juice.
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The main advantage of the HAWT is the increased efficiency in power production, and the smooth transfer of that power from the rotor to the gearbox. HAWTs are also generally mounted on taller towers, where they have exposure to higher wind velocities and present smaller footprints on the ground. However, they require tall cranes for set-up; they require a yaw system; and any maintenance required has to be done at the top of a tower. The photo here shows Henry duPont's colleague Kim Granbery at altitude during the installation of a new HAWT above the Western desert.
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KCXD-七刀

Henry duPont of Lorax Energy Systems in Block Island, Rhode Island, dropped by electronically to  enlighten us on the matter of vertical versus horizontal axis wind turbines (VAWT versus HAWT).

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Henry says the advantages of the VAWT configuration (like the Quietrevolution elsewhere in the Wind Power section ) are that the generator and gearbox can be housed on the ground, and even some distance away from that turbine; and that a VAWT is omnidirectional and requires no yaw mechanism. 垂直軸的好處：發電機和變速箱可以放在地上， 震動噪音會被吸收。也不需要偏航裝置。
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* |" F* F- ?* OThe disadvantages of typical VAWT systems are that they usually operate near the ground where there's not much wind; they produce wavy (sinusoidal) power pulses to drive mechanism; they don't start themselves in a breeze; and repair of the main bearing usually means having to take the whole machine apart. (The Quietrevolution appears to solve at least the first problem by being mount ed on a tower.) Most importantly, the VAWT is typically about 40% less efficient than the HAWT in energy production. According to Henry, you would need a VAWT almost twice the size of a HAWT to get the same amount of juice. 垂直軸缺點： 從結構上講， 垂直軸離地面更近， 風量小， 轉化為能量也小。

) \0 F8 {8 h. XThe main advantage of the HAWT is the increased efficiency in power production, and the smooth transfer of that power from the rotor to the gearbox. HAWTs are also generally mounted on taller towers, where they have exposure to higher wind velocities and present smaller footprints on the ground. However, they require tall cranes for set-up; they require a yaw system; and any maintenance required has to be done at the top of a tower. The photo here shows Henry duPont's colleague Kim Granbery at altitude during the installation of a new HAWT above the Western desert. 水平軸的最大優勢就是效率高， 主要原因是不需要很多的材料就可以得到很大的掃風面積， 通常也足夠高度， 獲得更多的風能。  而同樣多的材料在更接近地面的區域獲得風能會少很多。水平軸的缺點是安裝要求高， 維修難度大， 活動零部件多也會造成更高程度的磨損。

從效率上看， 獲得更多風能， 需要單位成本內的最大掃風面積。假設3米長的3個葉片可以獲得進30平方米的掃風面積， 而同樣3個3米的葉片， 作為垂直軸掃風面積只是一個3米*零點幾米的長方形面積， 而且還是近地面。
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. S) g3 Z2 j! o3 ^+ b6 `關于阻力型和升力型垂直軸：
http://www.mfginamerica.com/wind-sail-type-vertical-axis-wind-turbines-111011.aspx
+ A, _0 X  X9 O4 d6 m  A關鍵詞： 阻力型的葉輪轉速總是比風速要低， 而升力型的垂直軸葉輪轉速總是比風速快。 所以， 阻力型的垂直軸風機效率不到升力型垂直軸的一半。 但阻力型的特點是更皮實耐用。

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