為電力設(shè)計(jì)并研制三分之一比例的垂直軸風(fēng)力發(fā)電機(jī)外文文獻(xiàn)翻譯、中英文翻譯、外文翻譯
為電力設(shè)計(jì)并研制三分之一比例的垂直軸風(fēng)力發(fā)電機(jī)外文文獻(xiàn)翻譯、中英文翻譯、外文翻譯,電力,設(shè)計(jì),研制,三分之一,比例,垂直,風(fēng)力發(fā)電機(jī),外文,文獻(xiàn),翻譯,中英文
為電力設(shè)計(jì)并研制三分之一比例的垂直軸風(fēng)力發(fā)電機(jī)
DESIGN AND DEVELOPMENT OF A 1/3 SCALE VERTICAL
AXIS WIND TURBINE FOR ELECTRICAL POWERG
為電力設(shè)計(jì)并研制三分之一比例的垂直軸風(fēng)力發(fā)電機(jī)
摘要:本文通過對(duì)風(fēng)力渦輪機(jī)技術(shù)測(cè)量風(fēng)速的研究來闡述馬來西亞的發(fā)電技術(shù)。測(cè)量超過三分之一比例的原型垂直軸風(fēng)力發(fā)電機(jī)的風(fēng)速,其主要目的是預(yù)測(cè)全尺寸H型垂直軸風(fēng)力渦輪機(jī)的性能。風(fēng)力發(fā)電機(jī)產(chǎn)生的電力受發(fā)電機(jī)的兩個(gè)主要部分的影響:風(fēng)力發(fā)電和皮帶傳動(dòng)系統(tǒng)。葉片、阻力區(qū)系統(tǒng)和皮帶傳動(dòng)系統(tǒng)決定轉(zhuǎn)化成電力的風(fēng)力能,轉(zhuǎn)化成電力的風(fēng)受葉片、阻力區(qū)系統(tǒng)和皮帶傳送系統(tǒng)的影響。本文主要研究風(fēng)力和皮帶傳送系統(tǒng)的影響。塞格林工業(yè)大學(xué)熱工學(xué)系實(shí)驗(yàn)室為這個(gè)三分之一規(guī)模的風(fēng)力發(fā)電機(jī)組設(shè)計(jì)了一套葉片和拖動(dòng)裝置。風(fēng)力發(fā)電機(jī)組分別進(jìn)行5.89米/秒、6.08米/秒和7.02米/秒的風(fēng)速測(cè)試。從實(shí)驗(yàn)中計(jì)算出風(fēng)力分別為132.19W,145.40W和223.80W。目前的研究正在探索最大風(fēng)力。
關(guān)鍵詞: 皮帶傳送系統(tǒng); 雷諾數(shù); 風(fēng)力; 風(fēng)力發(fā)電機(jī)組
引言:風(fēng)能是一種動(dòng)能,與大氣運(yùn)動(dòng)密切相關(guān)。它已被用于航行船、磨糧食、灌溉數(shù)百年,風(fēng)力發(fā)電系統(tǒng)將動(dòng)能轉(zhuǎn)化為更加有用其他形式的能量,自古以來風(fēng)力發(fā)電系統(tǒng)就被應(yīng)用在灌溉、磨坊中;自20世紀(jì)初,它就開始被用來發(fā)電,許多國(guó)家尤其在農(nóng)村地區(qū)都安裝了水抽水風(fēng)車。
風(fēng)輪機(jī)是一臺(tái)把風(fēng)的動(dòng)能轉(zhuǎn)換成旋轉(zhuǎn)機(jī)械能的機(jī)器,然后被用來工作,在更先進(jìn)的機(jī)型里旋轉(zhuǎn)機(jī)械能通過發(fā)電機(jī)被轉(zhuǎn)換成電能,這是能量最通用的形式(菲茨沃特等,1996)。幾千年來,人們利用風(fēng)車抽水或磨糧食,即使進(jìn)入二十世紀(jì),身材高大、苗條、多葉片完全由金屬制成的風(fēng)力發(fā)電機(jī)也已經(jīng)進(jìn)入美國(guó)家庭和牧場(chǎng)將水抽到房子的管道系統(tǒng)或牲畜的飲水槽,第一次世界大戰(zhàn)后,主要的工作是開始發(fā)展可以產(chǎn)生電力的風(fēng)力渦輪機(jī),馬塞勒斯雅各布在1927年發(fā)明了一種可以為收音機(jī)和一些燈提供能量的原型,但僅僅如此。當(dāng)電力需求增加后,Jacobs的小型的有不足的風(fēng)力發(fā)電機(jī)開始不用。第一個(gè)大型風(fēng)力渦輪機(jī)由帕爾默考斯萊特普特南在1934年美國(guó)建立起構(gòu)思的,完成于1941年。這臺(tái)機(jī)器非常巨大,該身有36.6碼(33.5米)高,它的兩個(gè)不銹鋼葉片直徑有58碼(53米)。Putnam的風(fēng)力渦輪機(jī)可以產(chǎn)生一千二百五十〇千瓦電力,足以滿足一個(gè)小城鎮(zhèn)的需要(莫內(nèi)特等,1994)。然而由于機(jī)械故障在1945年就被遺棄了。隨著20世紀(jì)70年代石油禁運(yùn),美國(guó)又開始考慮從風(fēng)力渦輪機(jī)生產(chǎn)廉價(jià)電力的可行性。1975年,Mod-O原型開始運(yùn)作,這是一個(gè)有兩個(gè)21碼(19米)葉片的100千瓦渦輪。更多的原型機(jī)(Mod-OA, Mod-1, Mod-2)每個(gè)都比前一次更大更有能量。
目前,美國(guó)能源部的目標(biāo)是每臺(tái)機(jī)器超越3200千瓦。風(fēng)力渦輪機(jī)以許多不同的模式存在著,其中最引人注目的是垂直軸達(dá)里厄風(fēng)力發(fā)電機(jī),其形狀極像打蛋器(菲茨沃特等,1996)。該模型由制造商鼎力支持,是一個(gè)擁有約100萬千瓦能和三個(gè)長(zhǎng)度不超過33碼(30米)葉片的水平軸渦輪機(jī)。三葉片風(fēng)力渦輪機(jī)旋轉(zhuǎn)更加順暢,比兩片葉片更容易平衡。另外,更大的風(fēng)力發(fā)電機(jī)產(chǎn)生更多的能量,較小的型號(hào)是不太可能發(fā)生重大機(jī)械故障,從而更經(jīng)濟(jì)地維護(hù)。風(fēng)力發(fā)電場(chǎng)如雨后春筍般遍布了美國(guó),其中最引人注目的是加利福尼亞州。風(fēng)力發(fā)電場(chǎng)是一個(gè)在順風(fēng)風(fēng)力渦輪機(jī)生產(chǎn)領(lǐng)域的巨大陣列。風(fēng)力渦輪機(jī)的大量互聯(lián)是必要的,以便產(chǎn)生足夠的電力以滿足龐大人口的需求。目前,由幾個(gè)風(fēng)能源公司擁有在風(fēng)力發(fā)電場(chǎng)的17000臺(tái)風(fēng)力渦輪機(jī)每年每小時(shí)能產(chǎn)生的電力三十七點(diǎn)零億千瓦,足以滿足50萬家庭的能源需求。風(fēng)力渦輪機(jī)由三個(gè)基本部分組成:塔,機(jī)艙,轉(zhuǎn)子葉片。塔是由一個(gè)類似電塔的鋼格塔和一個(gè)鋼管塔里面有梯子可以通到發(fā)動(dòng)機(jī)艙兩部分組成,構(gòu)建風(fēng)力渦輪機(jī)的第一步是架設(shè)塔。雖然塔的鋼件在工廠制造,但是它們通常是在現(xiàn)場(chǎng)組裝。在安裝之前先把零件用螺栓連在一起,然后塔必須與地面保持水平,起重機(jī)將塔吊到他指定的位子上,所有螺栓擰緊并穩(wěn)定,然后再完整的測(cè)試,接下來,安裝玻璃鋼機(jī)艙。其在工廠里的內(nèi)部工作是把主傳動(dòng)軸,齒輪箱和刀片俯仰和偏航控制裝配到底座上(哈蒙斯,2004年),然后機(jī)艙閂上圍繞設(shè)備,在現(xiàn)場(chǎng),機(jī)艙是被吊過來與塔一起閂到位,此外,一個(gè)在轉(zhuǎn)子表面的風(fēng)力渦輪機(jī)的空氣動(dòng)力學(xué)在空氣動(dòng)力學(xué)領(lǐng)域內(nèi)是非常重要的,轉(zhuǎn)子軸帶了一個(gè)風(fēng)向標(biāo)通過在垂直方向安裝一個(gè)控制軸去定位葉片來改變風(fēng)向。采用轉(zhuǎn)子葉片間距調(diào)節(jié)其軸轉(zhuǎn)身使葉片和轉(zhuǎn)子的氣動(dòng)特性得到控制。風(fēng)能使旋翼飛機(jī)跟隨變換的風(fēng)向而導(dǎo)致旋翼飛機(jī)偏航,集線器是轉(zhuǎn)子剛性螺栓連接和轉(zhuǎn)子轉(zhuǎn)速相聯(lián)系是相對(duì)固定的電網(wǎng)頻率,未來只能得到更好的風(fēng)力渦輪機(jī)。用于風(fēng)能的潛力大部分尚未開發(fā),美國(guó)每年由風(fēng)產(chǎn)生的潛在電力總量約為10777億千瓦時(shí)(基思,2005)。這些新的風(fēng)力發(fā)電場(chǎng)示范著風(fēng)能如何可以幫助滿足國(guó)家日益增長(zhǎng)的既經(jīng)濟(jì)實(shí)惠又可靠的電力需求。隨著政府繼續(xù)鼓勵(lì)從而加快了其發(fā)展,這種可再生能源的競(jìng)爭(zhēng)日趨激烈的來源將在2020年提供至少百分之六的國(guó)家電力?,F(xiàn)在正進(jìn)行研究,以增加對(duì)風(fēng)力資源的知識(shí)。這包括在更多的地方測(cè)試其建立風(fēng)力發(fā)電廠的可能性,那里的風(fēng)強(qiáng)大有力且能被利用. 計(jì)劃實(shí)際上是把機(jī)器的壽命從5年提高到20年甚至30年,改善葉片的頻率,提供更好的控制,發(fā)展傳動(dòng)系統(tǒng)使壽命更長(zhǎng)從而允許更好的保護(hù)和接地。美國(guó)能源部最近建立一個(gè)計(jì)劃去開發(fā)最新研究,為了打造出比現(xiàn)在一個(gè)理想的風(fēng)力渦輪機(jī)效率百分之59.3還要高的風(fēng)力發(fā)電機(jī)(Milligan和Artig,1999) ,也就是說,59.3風(fēng)的能源百分之可以被捕獲。在實(shí)際使用中渦輪機(jī)效率約百分之三十,美國(guó)能源部還簽約三家公司進(jìn)行調(diào)查以減少機(jī)械故障,該項(xiàng)目始于1992年春,將延伸到本世紀(jì)末。風(fēng)力發(fā)電機(jī)將在未來幾年內(nèi)會(huì)變得越加普遍,在世紀(jì)之初我們應(yīng)該看到被妥善安置且高效耐用以及眾多的渦輪機(jī)。據(jù)風(fēng)力渦輪機(jī)的背景調(diào)查,H型垂直軸風(fēng)力發(fā)電機(jī)在雪蘭莪工業(yè)大學(xué)的熱工實(shí)驗(yàn)室被設(shè)計(jì)出來,他們以具備自主研發(fā)的能力。此外,這臺(tái)機(jī)器已經(jīng)被設(shè)計(jì)允許各種各樣的修改,比如葉片的輪廓,而且還進(jìn)行了多次的測(cè)試。這個(gè)設(shè)計(jì)的第一部分包括了研究,集思廣益,工程分析,渦輪機(jī)的設(shè)計(jì)選擇和樣機(jī)試驗(yàn)。使用通過適當(dāng)?shù)恼{(diào)查結(jié)果獲得的數(shù)據(jù),最終完整的渦輪機(jī)就被設(shè)計(jì)建造出來了。風(fēng)力發(fā)電機(jī)以軸為標(biāo)準(zhǔn)可以被分為兩類,水平軸風(fēng)力機(jī)(HAWT)和垂直軸風(fēng)力發(fā)電機(jī)(VAWT)。水平軸風(fēng)力機(jī)在近地面很難被操作,動(dòng)蕩的風(fēng)流會(huì)導(dǎo)致葉片的偏航,則葉片軸承得做得更加的光滑來避免更多層次的風(fēng)流,水平軸風(fēng)力機(jī)也很難去安裝,這需要非常高且昂貴的起重機(jī)和熟練的操作技巧,順風(fēng)變種會(huì)遭遇疲勞,由湍流會(huì)引起結(jié)構(gòu)失效,它的高度為低空飛行的飛機(jī)造成了安全隱患。除此之外,水平軸風(fēng)力渦輪機(jī)的空氣動(dòng)力學(xué)是相當(dāng)復(fù)雜的,在葉片上的氣流跟遠(yuǎn)離渦輪機(jī)的氣流是不一樣的。這種十分自然的從空氣中提取能量的方式通過渦輪機(jī)使風(fēng)向改變。另外,在旋轉(zhuǎn)體表面,應(yīng)用于風(fēng)力發(fā)電機(jī)的空氣動(dòng)力學(xué)包括了幾乎在其他應(yīng)用領(lǐng)域看不到的效用。學(xué)者們提出了許多不同構(gòu)造類型的垂直軸風(fēng)力發(fā)電機(jī)。達(dá)里厄的垂直型風(fēng)力發(fā)電機(jī)是最常見的,我們廣泛使用它來產(chǎn)生電能。然而,達(dá)里厄的發(fā)電機(jī)也像劣質(zhì)的能源市場(chǎng)一樣遭受構(gòu)造性問題。為了提高風(fēng)力發(fā)電機(jī)的效用,本文致力于設(shè)計(jì)并建立三分之一比例的H型垂直軸風(fēng)力發(fā)電機(jī),能夠根據(jù)風(fēng)的流動(dòng)而自我啟動(dòng)。垂直軸風(fēng)力發(fā)電機(jī)的高效性能將改變?nèi)藗儗?duì)風(fēng)能被利用的標(biāo)準(zhǔn)的思考,而且能激勵(lì)未來垂直軸風(fēng)力發(fā)電機(jī)的設(shè)計(jì)和研究。提高風(fēng)力發(fā)電機(jī)性能的研究包括對(duì)拖動(dòng)裝置的研究。
風(fēng)機(jī)設(shè)計(jì) 理論分析 在這個(gè)研究里,皮帶驅(qū)動(dòng)系統(tǒng)由皮帶的傳動(dòng)計(jì)算和被考慮在內(nèi)的V帶這幾部分組成,因此主要的計(jì)算是在這個(gè)系統(tǒng)里小型和大型皮帶輪包角、皮帶的長(zhǎng)度、滑輪的速度、張力比和皮帶的傳動(dòng)功率。V帶結(jié)構(gòu)如圖一所示,闡明了V帶的主要部分,例如:大輪的直徑用3表示,小輪的直徑用2表示,大輪的包角用θ3表示,小輪的包角用θ2表示。C表示著大輪和小輪兩圓心間的距離。
大皮帶輪包角
大型滑輪包角的定義是(約瑟夫等,2004年)
(1)
將大輪直徑D3 =30.48×10-2m,小輪直徑D2 =5.08 ×10 -2m和圓心距C=0.3048m這些數(shù)據(jù)帶入到公式(1)中,可以獲得大輪的包角θ3 = 229.25°。
小皮帶輪包角
小型滑輪包角的定義是(約瑟夫等,2004年)
(2)
在公式(2)中利用上述相同的數(shù)據(jù)可以得到小輪的包角θ2 = 130.75°。
中心半徑長(zhǎng)
中心半徑長(zhǎng)度的定義是(約瑟夫等,2004年)
(3)
將大輪直徑D3 =30.48×10-2m,小輪直徑D2 =5.08 ×10 -2m和圓心距C=0.3048m這些數(shù)據(jù)帶入到公式(3)中,可獲得半徑長(zhǎng)度L =1.221 m。
拉緊側(cè)張力和松弛側(cè)張力的比率
拉緊側(cè)張力和松弛側(cè)張力的比率的定義是(約瑟夫等,2004年)
(4)
皮帶的摩擦系數(shù)為0.25,θ3是前面提到的小輪包角的弧度(4 rad),T1是張力T2是松弛力,將上述提到的數(shù)據(jù)代入到公式(3)中,可以得到拉緊側(cè)張力和松弛側(cè)張力的比率T1/T2 = 1.545
拉緊側(cè)皮帶張力
拉緊側(cè)皮帶張力的定義是(佐爾格,1996年)
T1 = Wg (5)
通過選擇渦輪機(jī)上部分的總重量W=17kg和采用重力加速度g=9.81 m/s2,然后代入公式(5),可以獲得拉緊側(cè)皮帶張力T1 = 166.77 N
松弛側(cè)張力
使用公式4中T1的數(shù)值,可以獲得松弛邊的張力T2 = 107.94 N。
滑輪速度
滑輪的速度的定義是(約瑟夫等,2004年)
(6)
皮帶傳送的能量
皮帶傳送的能量的定義是(約瑟夫等,2004年)
PB = (T1 – T2 )V (7)
將拉緊側(cè)張力T1=166.77N、松弛側(cè)張力T2=107.94N和滑輪速度V=2.84m/s帶入到公式7中,可以獲得皮帶傳送的能量PB = 167.08 W。
原型設(shè)計(jì)
1/3比例的垂直軸風(fēng)力發(fā)電機(jī)的組件是在雪蘭莪工業(yè)大學(xué)的結(jié)構(gòu)實(shí)驗(yàn)室,通過CATIA軟件設(shè)計(jì)出來的。將這些組件組裝在一起能預(yù)示實(shí)際比例的垂直軸風(fēng)力發(fā)電機(jī)的實(shí)際效用。風(fēng)力發(fā)電機(jī)由三個(gè)連接發(fā)動(dòng)機(jī)轉(zhuǎn)子的錐形葉片組成,并且在開放性的大廳做過測(cè)試。兩端的尖頂處為風(fēng)力發(fā)電機(jī)葉片的機(jī)翼,隨著它在氣流中的運(yùn)作而產(chǎn)生可控制的空氣動(dòng)力,如圖2所示。接下來會(huì)描述另一個(gè)已經(jīng)被設(shè)計(jì)出來建造風(fēng)力發(fā)電機(jī)的重要組件。
基面和基表
這個(gè)基礎(chǔ)材料選擇為鋼是因?yàn)樗母叨仁?096mm,它的重量為15kg,這個(gè)基礎(chǔ)本身不支持風(fēng)力發(fā)電機(jī)產(chǎn)生的瞬間扭矩,所以設(shè)定了基地?cái)U(kuò)展和連接支架,為了連接4個(gè)鋼支架,以38.10 mm × 76.2 mm的鋼鐵做成的底托盤為基礎(chǔ)鋼件,該38.10 mm × 38.10 mm結(jié)構(gòu)的鋼板提供快速裝配和拆卸渦輪機(jī)基礎(chǔ)結(jié)構(gòu)的能力。
底部托架需要四個(gè)簡(jiǎn)單的焊縫,為了達(dá)到快速裝配,平頭螺栓需要焊接在這個(gè)位置,用四張1219.20 mm×2438.40 mm ×19.05 mm大小的鋼板來建造一個(gè)堿基延伸,為砝碼提供大托盤。中心鋼板和另外兩片在同一邊,還有在上面的兩片與底部的兩片相垂直。這樣就建造了一個(gè)2438.40 mm × 2438.40 mm規(guī)模的基表,如圖三所示。
軸和軸承
軸用鋼為材料,設(shè)計(jì)成城邦柄的形狀,重14千克,直徑為30 mm,長(zhǎng)2133.6 mm。它的表面光滑,當(dāng)與軸承接觸的時(shí)候,軸旋轉(zhuǎn)的十分平滑。最大限度的減少所需的啟動(dòng)扭矩對(duì)風(fēng)力渦輪機(jī)自我啟動(dòng)是十分關(guān)鍵的,因而,也對(duì)該項(xiàng)目的成功與否十分重要。設(shè)計(jì)用于風(fēng)力渦輪機(jī)的軸是不能打撈的。軸承價(jià)格昂貴,為特定的項(xiàng)目設(shè)定的雙輪軸承已經(jīng)投入使用,主要軸集中在一起。這種組合能使摩擦最小化,軸承壽命最長(zhǎng)化,并提供安全的操作環(huán)境。每個(gè)軸承的直徑是88 mm,重300 克。
支撐臂和阻力裝置
鋼鐵用于三個(gè)支撐搖臂去維持?jǐn)y帶最小慣性扭距和離心力的輕量級(jí)組裝,連接臂是葉片和中心軸的介質(zhì),拖動(dòng)設(shè)備用輕質(zhì)塑料(鑄塑)制成用來安裝在主軸上。拖動(dòng)裝置的長(zhǎng)度約為762毫米,寬度182.88毫米。
風(fēng)力發(fā)電機(jī)葉片設(shè)計(jì)
頂部和底部的每一個(gè)葉片都有1066.8 mm ×139.7 mm ×50.8 mm深矩形截面用來更容易地連接徑向臂和被動(dòng)變槳系統(tǒng)。在這項(xiàng)研究中角尖被設(shè)定為葉片的形狀,因?yàn)槿~片有抵抗風(fēng)流量和在風(fēng)流量中產(chǎn)生的快速旋轉(zhuǎn)的性能。風(fēng)力發(fā)電機(jī)最后的組裝定于雪蘭莪工業(yè)大學(xué)的熱工實(shí)驗(yàn)室里展現(xiàn)在圖4中。在裝配工程中共有18個(gè)零件和15個(gè)螺栓組裝在一起。在垂直軸風(fēng)力發(fā)電機(jī)全部組裝期間,軸連接到中心部位和發(fā)電機(jī)。
實(shí)驗(yàn)方法
雪蘭莪工業(yè)大學(xué)的風(fēng)力發(fā)電機(jī)原型被安裝在雪蘭莪工業(yè)大學(xué)的熱工實(shí)驗(yàn)室里,也進(jìn)行了許多初步的實(shí)驗(yàn),而且都操作成功。在開始操作之前,蓄電池和交流發(fā)電機(jī)端部都進(jìn)行嚴(yán)格地檢查,它們都連接著燈和開關(guān),這樣風(fēng)力發(fā)電機(jī)能夠旋轉(zhuǎn)。由于風(fēng)力發(fā)電機(jī)葉片旋轉(zhuǎn)產(chǎn)生的電壓,所連接的電燈就開啟了。(圖5)
產(chǎn)生的電壓讀數(shù)和各自的渦輪旋轉(zhuǎn)都被記錄下來了。周邊的壓力和溫度分別用壓力機(jī)和溫度計(jì)測(cè)量,為了在雪蘭莪工業(yè)大學(xué)的環(huán)境實(shí)驗(yàn)室里總結(jié)出對(duì)空氣密度的評(píng)價(jià)。
我們也測(cè)量了風(fēng)速產(chǎn)生的能量,記錄在標(biāo)本測(cè)量部分。主要的測(cè)試都是在塞格林工業(yè)大學(xué)的熱工學(xué)系實(shí)驗(yàn)室一個(gè)開放的大廳進(jìn)行的,那里的風(fēng)速為4到 6 m/s,有時(shí)陣風(fēng)會(huì)使風(fēng)速達(dá)到7 m/s。
這測(cè)試中,風(fēng)力渦輪機(jī)根據(jù)設(shè)計(jì)進(jìn)行運(yùn)作,然后打開葉片,風(fēng)被推動(dòng),最終它驗(yàn)證了葉片關(guān)閉時(shí)產(chǎn)生的足夠的升力。似乎渦輪機(jī)在不產(chǎn)生升力的地區(qū)慢速太多。所以葉片保持開放是為了能夠旋轉(zhuǎn)。其次,開放的葉片能檢測(cè)在阻力位置中可獲得的最大轉(zhuǎn)速。在這個(gè)位置上,我們觀察到很多的能使渦輪機(jī)旋轉(zhuǎn)的迎風(fēng)面。
樣本計(jì)算
絕對(duì)壓力p = 1.01×105N/m2 ,溫度T = 38.5oC=311.5K。利用理想氣體方程式的空氣密度的狀態(tài)ρ是 1.13 kg/m 3,其定義是(伯廷,2002)
(8)
其中,壓強(qiáng)p是1.01 × 10 5 N/m2 ,溫度T 是311.5 K,空氣氣體常數(shù)R是 287.05 Nm/kg K。空氣粘度μ用薩瑟蘭的方程式計(jì)算(伯廷,2002),其方程式如下,μ是動(dòng)力粘度。
(9)
T為311.5 K時(shí),方程式9算出μ為1.90×10-5kg/m s?;谙议L(zhǎng)的雷諾數(shù)的定義是(安德森,1996)
(10)
在方程式10中,用空氣密度ρ等于1.13 kg/m3 ,自由流速度ν= 5.89 m/s,動(dòng)力粘度μ=1.90×10-5kg/ms,弦長(zhǎng)c = 0.1397 m,得出雷諾數(shù)Re = 0.4 ×105。
對(duì)余下的速度,其相對(duì)應(yīng)的雷諾數(shù)呈現(xiàn)在表1中,長(zhǎng)方形葉片的單表面面積的定義如下(貝爾坦,2002):
表 1自由流速度和雷諾數(shù)
序列號(hào) 自由流速度y(m/s) 雷諾數(shù)
1 5.89 0.49 × 105
2 6.08 0.51 × 105
3 7.02 0.58 × 105
S = bc (11)
對(duì)于風(fēng)力發(fā)電機(jī)總的表面積ST = 1.145 m2 且定義為(貝爾坦,2002):
ST = (S1)T + (S2)T (12)
在這里葉片的總表面積為(S1)T = 0.4482 m2 ,總的阻力面面積為(S2)T = 0.6968m2
風(fēng)力渦輪機(jī)的功率定義為(法官和云,2004)
(13)
在這里空氣密度ρ∞ = 1.130kg/m3,總的表面積ST =1.145m 2 ,風(fēng)速ν∞ = 5.89m/s,把這些值代入方程式13,我們可以得到:
對(duì)余下的速度與其相對(duì)應(yīng)的的風(fēng)能呈現(xiàn)在表2中
結(jié)果與討論
試驗(yàn)用3個(gè)不同的速度5.89 m/s, 6.08m/s and 7.02 m/s在雪蘭莪工業(yè)大學(xué)公開實(shí)施,以測(cè)量出來的的速度為基礎(chǔ),前面一個(gè)環(huán)節(jié)已經(jīng)計(jì)算出了為原型提供的風(fēng)能,如表2所示,對(duì)于表1中的雷諾數(shù)計(jì)算值已在上一節(jié)得到介紹。
在已經(jīng)實(shí)施的測(cè)試中,對(duì)于測(cè)量出的速度變量,風(fēng)力和雷諾數(shù)之間的關(guān)系的進(jìn)一步了解會(huì)在下表中呈現(xiàn)。
表 2.速度和相對(duì)應(yīng)風(fēng)能
序列號(hào). 速度 (m/s) 風(fēng)能 (W)
1 5.89 132.19
2 6.08 145.40
3 7.02 223.80
雷諾數(shù)
雷諾數(shù)的數(shù)值越高,表明風(fēng)力渦輪機(jī)能產(chǎn)生更多的力量,這是因?yàn)轱L(fēng)速值的增加。風(fēng)速值是在風(fēng)速為7.02 m/s的測(cè)試中測(cè)量并記錄下來的。
翼型幾何
為三刃垂直軸風(fēng)力發(fā)電機(jī)選擇適當(dāng)翼型在設(shè)計(jì)討論中是十分重要的。我們必須考慮不同的形狀會(huì)帶來不同的優(yōu)缺點(diǎn)。然后,由于翼型和刀片而影響風(fēng)流的喜好是不明顯得,在刀片循環(huán)中產(chǎn)生的阻力也是可以忽略的。此外,這個(gè)模型中設(shè)計(jì)和使用的刀片不同于國(guó)家航空咨詢委員會(huì)的0012或者0015,它們主要應(yīng)用于低雷諾數(shù)區(qū)。但是現(xiàn)在這項(xiàng)方案中選擇的型號(hào),當(dāng)軸在風(fēng)流中旋轉(zhuǎn)時(shí),仍然具有持久耐用性和高效能性。
拖動(dòng)設(shè)備幾何
當(dāng)前項(xiàng)目中使用的拖動(dòng)設(shè)備能為葉片提供外部支持,通過收集最大的風(fēng)流量,初始化葉片和軸的旋轉(zhuǎn)。拖動(dòng)設(shè)備對(duì)于小風(fēng)流也十分敏銳,即使在設(shè)定的地點(diǎn)風(fēng)速十分小葉能讓葉片和軸旋轉(zhuǎn)起來。在對(duì)于這個(gè)模型進(jìn)行測(cè)試期間,風(fēng)被外部的阻力堵塞或者圍繞到其他地方。把凈扭距因式分解,然后驅(qū)動(dòng)外部阻力圍繞著軸,誘導(dǎo)渦輪旋轉(zhuǎn),從而產(chǎn)生出離心力。旋轉(zhuǎn)速度會(huì)慢慢增大直到一個(gè)渦輪機(jī)的移動(dòng)速度足以被上升力驅(qū)動(dòng)的臨界點(diǎn)。開式和閉式的阻力機(jī)制設(shè)計(jì)出離心力在這個(gè)臨界速度克服慣性力和直接力的能力。特別是,這設(shè)備在低速尖率比也能有一個(gè)非常強(qiáng)大的扭矩特性,意味著它能自動(dòng)啟動(dòng)。然而困難的是調(diào)試的扭矩測(cè)量和控制系統(tǒng)目前為止已經(jīng)推遲了一定的采集測(cè)試數(shù)據(jù)。
渦輪機(jī)的可行性比較
從目前1 / 3規(guī)模的風(fēng)力發(fā)電站計(jì)算出來的風(fēng)能看,根據(jù)使用類型和估計(jì)費(fèi)用對(duì)現(xiàn)有的發(fā)電機(jī)進(jìn)行全面的比較,如表3所示。
臥龍崗大學(xué)的項(xiàng)目已經(jīng)生產(chǎn)出了使用傳動(dòng)系統(tǒng)可獲得最大風(fēng)能700W,格里菲斯大學(xué)已經(jīng)使用類似的系統(tǒng)生產(chǎn)出了550W電力(庫(kù)伯&肯尼迪,2003;克瑞克,2003)。在當(dāng)前項(xiàng)目中被測(cè)試的原型用皮帶和滑輪系統(tǒng)產(chǎn)生了167W電力。根據(jù)對(duì)風(fēng)速的評(píng)估,當(dāng)風(fēng)速增大時(shí),當(dāng)前的模型能超越現(xiàn)有的設(shè)備。當(dāng)前的模型能在風(fēng)速增長(zhǎng)到20 m/s時(shí)發(fā)出567.33W電力,在增長(zhǎng)到25 m/s時(shí)發(fā)出709.17W電力。所有的比較的表面,在價(jià)格和產(chǎn)生的能力方面考慮,當(dāng)前使用皮帶和滑輪系統(tǒng)的模型比其它使用傳動(dòng)系統(tǒng)的產(chǎn)品更具有可行性。
總結(jié)
此次實(shí)驗(yàn)的總結(jié)如下:
(1) 當(dāng)風(fēng)力最大增加到12 m/s時(shí),模型產(chǎn)生的風(fēng)力最大能達(dá)到1000W。
(2) 調(diào)查研究表明當(dāng)20 m/s時(shí)產(chǎn)生567.33W電力,在增加到25 m/s時(shí)發(fā)出709W電力。
術(shù)語(yǔ)
Symbol Meaning Unit
p Absolute pressure (N/m2)
T Temperature (K)
R Gas constant (Nm/kg K)
ρ∞ Air density (kg/m3)
μ∞ Air viscosity (kg m/s)
ν∞ Free stream velocity (m/s)
c Chord length (m)
Re Reynolds number (Dimensionless)
B Blade height (m)
S1 Blade frontal surface area (m2)
S2 Drag device frontal area (m2)
ST Total frontal area (m2)
Pwind Wind power (W)
鳴謝 作者對(duì)雪蘭莪工業(yè)大學(xué)提供的資金支持,工程學(xué)院提供全部的工程設(shè)備表示衷心的感謝。
參考文獻(xiàn):
Anderson, J.D.Jr. (1999) Aircraft Performance and Design. McGraw Hill Companies Inc., U.S.A.
Bench, S.E., Cloud, P.K. (2004) The Measure, Predict and Calculate the Power response of an Operating Wind Turbine. 1 st Ed., London, Jepson Pub, 366 p. Bertin, J. J. (2002) Aerodynamics for the Engineer. New Jersey, Prentice Hall, Inc., U.S.A.
Cooper, P., Kennedy, O. (2003) Development and Analysis of a Novel Vertical Axis Wind Turbine. Bachelor. Thesis, University of Wollongong, NSW 2522, Australia
Fitzwater, L.M., Cornell, C.A., Veers, P.S. (1996) Using Environmental Contours to Predict Extreme Events on Wind Turbines. Wind Energy Symp., AIAA/ASME, 9, 244–258.
Hammons, T.J. (2004) Technology and Status of Developments in Harnessing the World’s Untapped Wind-Power Resources. Electricity Power Components and Systems. No.12, p. 32.
Joseph, E.S, Charles, R.M, Richard, G.B. (2004) Mechanical Engineering Design. 7 th Ed., United State of America. p. 1030.
Keith, David W. (2005) The Influence of Large-Scale Wind Power on Global Climate. Proc. National Academy of Sciences, Washington D.C, Vol. 101, pp. 12–56.
Kirke, B.K. (2003) Evaluation of self-starting vertical axis wind turbines for stand alone applications. PhD Thesis, Griffith University, Australia.
Milligan, M.R. & Artig, R. (1999) Choosing Wind Power Plant Locations and Sizes Based on Electric Reliability Measures Using Multiple-Year Wind Speed Measurements. National Renewable Energy Laboratory, 8, 52p.
Monett, G., Poloni, C. & Diviacco, B. (1994) Optimization of wind turbine positioning in wind farms by means of large development. J. of Wind Engng and Ind. Aerod 23(4), 105–16
Sorge, F. (1996) A qualitative-quantitative approach to v-belt mechanics.ASME,J.of Mechanical Design 118(8)
DESIGN AND DEVELOPMENT OF A 1/3 SCALE VERTICAL
AXIS WIND TURBINE FOR ELECTRICAL POWERG
Abstract: This research describes the electrical power generation in Malaysia by the measurement of wind velocity acting on the wind turbine technology. The primary purpose of the measurement over the 1/3 scaled prototype vertical axis wind turbine for the wind velocity is to predict the performance of full scaled H-type vertical axis wind turbine. The electrical power produced by the wind turbine is influenced by its two major part, wind power and belt power transmission system. The blade and the drag area system are used to determine the powers of the wind that can be converted into electric power as well as the belt power transmission system. In this study both wind power and belt power transmission system has been considered. A set of blade and drag devices have been designed for the 1/3 scaled wind turbine at the Thermal Laboratory of Faculty of Engineering, Universiti Industri Selangor (UNISEL). Test has been carried out on the wind turbine with the different wind velocities of 5.89 m/s, 6.08 m/s and 7.02 m/s. From the experiment, the wind power has been calculated as 132.19 W, 145.40 W and 223.80W.The maximum wind power is considered in the present study.
Keywords: Belt power transmission system; Reynolds number; wind power; wind turbine
INTRODUCTION Wind energy is the kinetic energy associated with the movement of atmospheric air. It has been used for hundreds of years for sailing, grinding grain, and for irrigation. Wind energy systems convert this kinetic energy to more useful forms of power. Wind energy systems for irrigation and milling have been in use since ancient times and since the beginning of the 20th century, it is being used to generate electric power. Windmills for water pumping have been installed in many countries particularly in the rural areas.
Wind turbine is a machine that converts the wind's kinetic energy into rotary mechanical energy, which is then used to do work. In more advanced models, the rotational energy is converted into electricity, the most versatile form of energy, by using a generator (Fitzwater et al., 1996). For thousands of years people have used windmills to pump water or grind grain. Even into the twentieth century tall, slender, multi-vaned wind turbines made entirely of metal were used in American homes and ranches to pump water into the house's plumbing system or into the cattle's watering trough. After World War I, work was begun to develop wind turbines that could produce electricity. Marcellus Jacobs invented a prototype in 1927 that could provide power for a radio and a few lamps but little else. When demand for electricity increased later, Jacobs's small inadequate wind turbines fell out of use. The first large-scale wind turbine built in the United States was conceived by Palmer Cosslett Putnam in 1934; he completed it in 1941. The machine was huge. The tower was 36.6 yards (33.5 meters) high, and its two stainless steel blades had diameters of 58 yards (53 meters). Putnam's wind turbine could produce 1,250 kilowatts of electricity, or enough to meet the needs of a small town (Monett et al., 1994). It was, however, abandoned in 1945 because of mechanical failure. With the 1970s oil embargo, the United States began once more to consider the feasibility of producing cheap electricity from wind turbines. In 1975 the prototype Mod-O was in operation. This was a 100 kilowatt turbine with two 21-yard (19-meter) blades. More prototypes followed (Mod-OA, Mod-1, Mod-2, etc.), each larger and more powerful than the one before.
Currently, the United States Department of Energy is aiming to go beyond 3,200 kilowatts per machine. Many different models of wind turbines exist, the most striking being the vertical-axis Darrieus, which is shaped like an egg beater (Fitzwater et al., 1996). The model most supported by commercial manufacturers, however, is a horizontal-axis turbine, with a capacity of around 100 kilowatts and three blades not more than 33 yards (30 meters) in length. Wind turbines with three blades spin more smoothly and are easier to balance than those with two blades. Also,while larger wind turbines produce more energy, the smaller models are less likely to undergo major mechanical failure, and thus are more economical to maintain. Wind farms have sprung up all over the United States, most notably in California. Wind farms are huge arrays of wind turbines set in areas of favorable wind production. A great number of interconnected wind turbines are necessary in order to produce enough electricity to meet the needs of a sizable population. Currently, 17,000 wind turbines on wind farms owned by several wind energy companies produce 3.7 billion kilowatt-hours of electricity annually, enough to meet the energy needs of 500,000 homes. A wind turbine consists of three basic parts: the tower, the nacelle, and the rotor blades. The tower is either a steel lattice tower similar to electrical towers or a steel tubular tower with an inside ladder to the nacelle. The first step in constructing a wind turbine is erecting the tower. Although the tower's steel parts are manufactured off site in a factory, they are usually assembled on site. The parts are bolted together before erection, and the tower is kept horizontal until placement. A crane lifts the tower into position, all bolts are tightened, and stability is tested upon completion. Next, the fiberglass nacelle is installed. Its inner workings main drive shaft, gearbox, and blade pitch and yaw controls are assembled mounted onto a base frame at a factory (Hammons, 2004). The nacelle is then bolted around the equipment. At the site, the nacelle is lifted onto the completed tower and bolted into place. In addition, the aerodynamics of a wind turbine at the rotor surface is very much important in aerodynamic fields. The rotor axis is brought to a vertical orientation with a wind vane mounted on a control shaft to orientate the blades with changing wind direction. Using pitch regulation the rotor blades turn around their axis so that the aerodynamic characteristics of the blade and rotor are controlled. The rotor is yaw out of the wind which turns the rotor plane to follow the changing wind direction. The hub is connected to the rotor with rigid bolt connection and the rotational speed of the rotor is fixed relative to the frequency of the grid. The future can only get better for wind turbines. The potential for wind energy is largely untapped. The total amount of electricity that could potentially be generated from wind in the United States has been estimated at 10,777 billion kWh annually (Keith, 2005). These new wind farms demonstrate how wind energy can help to meet the nation’s growing need for affordable, reliable power. With continued government encouragement to accelerate its development, this increasingly competitive source of renewable energy will provide at least six percent of the nation’s electricity by 2020. Research is now being done to increase the knowledge of wind resources. This involves the testing of more and more areas for the possibility of placing wind farms where the wind is available and strong. Plans are in effect to increase the life span of the machine from five years to 20 to 30 years, improve the efficiency of the blades, provide better controls, develop drive trains that last longer, and allow for better surge protection and grounding. The United States Department of Energy has recently set up a schedule to implement the latest research in order to build wind turbines with a higher efficiency rating than is now possible (the efficiency of an ideal wind turbine is 59.3 percent (Milligan & Artig, 1999). That is, 59.3 percent of the wind’s energy can be captured. Turbines in actual use are about 30 percent efficient). The United States Department of Energy has also contracted three corporations to investigate ways to reduce mechanical failure. This project began in the spring of 1992 and will extend to the end of the century. Wind turbines will become more prevalent in upcoming years. The turn of the century should see wind turbines that are properly placed, efficient, durable, and numerous. From the investigation of this wind turbine background, an H-type, vertical axis wind turbine has been designed and built in thermal Laboratory Universiti Industri Selangor that has the capability to self-start. In addition, this turbine has been designed to allow a variety of modifications such as blade profile and pitching to be tested. The first part of the design process, which included research, brainstorming, engineering analysis, turbine design selection, and prototype testing have been incorporated. Using data obtained through proper investigation results, the final full-scale turbine has been designed and built. Wind turbines can be separated into two types based by the axis in which the turbine rotates namely horizon
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