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中小型水電站水輪機轉輪改型設計的必要性和可行性

2020-12-01 11:18:09      來源:宜賓富源      點擊:0
簡介: 中小型水電站技術改造是水電事業發展的重要組成部分,本文通過對我國中小型水電站發展現狀的論述,分析了在中小型水電站技術改造中水輪機轉輪改型設計的必要性和可行性,并介紹了當前水輪機轉輪設計、測試和制造方面的新技術。
關鍵字:中(zhong)小型水電站 水輪機轉輪 改型設計
相關站(zhan)中站(zhan): 水(shui)輪機


1我國中(zhong)小型水電站(zhan)的發展現狀


建國(guo)以(yi)來(lai),我(wo)國(guo)水(shui)電(dian)(dian)(dian)(dian)建設(she)取得(de)了(le)巨大成就,據統(tong)計我(wo)國(guo)常規(gui)(gui)水(shui)電(dian)(dian)(dian)(dian)裝機(ji)容量已達(da)到7700×104kW,其中,中小(xiao)型(xing)水(shui)電(dian)(dian)(dian)(dian)站4.5×104余(yu)座,擁有機(ji)組7×104余(yu)臺,總(zong)裝機(ji)容量達(da)2020×104kW,有近一半為50~60年(nian)代(dai)制(zhi)造的設(she)備[1]。由(you)于當(dang)時條(tiao)件限制(zhi),這些電(dian)(dian)(dian)(dian)站的水(shui)輪機(ji)多數是應用前蘇聯(lian)40~50年(nian)代(dai)的技(ji)術(shu),制(zhi)造技(ji)術(shu)落后,效率較低(di),過流能力(li)差,總(zong)的能量指(zhi)標(biao)偏低(di)。加上(shang)大部(bu)分國(guo)產機(ji)組生(sheng)產于特殊年(nian)代(dai),不按電(dian)(dian)(dian)(dian)廠各(ge)種條(tiao)件而硬性(xing)套用定(ding)型(xing)圖紙,或僅按模型(xing)試驗的特定(ding)角度硬性(xing)規(gui)(gui)定(ding)設(she)計,致使(shi)原來(lai)水(shui)力(li)效率不高(gao)的轉輪又偏離了(le)高(gao)效率區(qu)。還(huan)有性(xing)能指(zhi)標(biao)較低(di),如高(gao)效區(qu)狹小(xiao)、振動(dong)區(qu)范圍大、空化性(xing)能差等,對機(ji)組的安全穩(wen)定(ding)運行產生(sheng)了(le)嚴重的影(ying)響,很大程度上(shang)降(jiang)低(di)了(le)電(dian)(dian)(dian)(dian)站設(she)備的運行管理水(shui)平和效益(yi)。


另外(wai)(wai),由(you)于(yu)大部(bu)(bu)分電(dian)(dian)(dian)(dian)(dian)站(zhan)已(yi)運行(xing)(xing)了(le)三四十年(nian)(nian),機組(zu)設備(bei)在(zai)(zai)性能(neng)和(he)結構方面都已(yi)陳舊(jiu)、事故(gu)增(zeng)(zeng)多、檢修頻繁(fan)。長期(qi)(qi)運行(xing)(xing)已(yi)使過(guo)流部(bu)(bu)件(jian)(jian)磨(mo)損,特(te)別是(shi)(shi)轉(zhuan)輪、導葉(xie)等部(bu)(bu)件(jian)(jian)由(you)于(yu)空蝕和(he)磨(mo)損,葉(xie)型(xing)遭到破壞,間(jian)隙增(zeng)(zeng)加而使效率(lv)(lv)(lv)下降。根據國外(wai)(wai)有(you)關資料(liao)介紹,效率(lv)(lv)(lv)下降約為(wei)2%。特(te)別是(shi)(shi)有(you)些電(dian)(dian)(dian)(dian)(dian)站(zhan)或由(you)于(yu)當年(nian)(nian)是(shi)(shi)套用(yong)機組(zu),或由(you)于(yu)電(dian)(dian)(dian)(dian)(dian)站(zhan)參數(shu)發(fa)生變化,使機組(zu)長期(qi)(qi)在(zai)(zai)低(di)效率(lv)(lv)(lv)下運行(xing)(xing),浪費(fei)能(neng)源,亟待早日解決。與此形成鮮明(ming)對比的(de)(de)是(shi)(shi),近年(nian)(nian)來(lai)(lai),隨著(zhu)國民(min)經濟的(de)(de)發(fa)展和(he)人(ren)民(min)生活(huo)水平的(de)(de)不(bu)斷提(ti)高,電(dian)(dian)(dian)(dian)(dian)力(li)(li)負(fu)荷峰(feng)谷(gu)差(cha)愈(yu)來(lai)(lai)愈(yu)大,增(zeng)(zeng)大中小型(xing)電(dian)(dian)(dian)(dian)(dian)廠(chang)在(zai)(zai)電(dian)(dian)(dian)(dian)(dian)網系統中的(de)(de)調(diao)峰(feng)、調(diao)頻能(neng)力(li)(li)也愈(yu)顯重要。而電(dian)(dian)(dian)(dian)(dian)力(li)(li)系統越來(lai)(lai)越多地要求水電(dian)(dian)(dian)(dian)(dian)機組(zu)特(te)別是(shi)(shi)中小型(xing)水電(dian)(dian)(dian)(dian)(dian)機組(zu)擔負(fu)調(diao)峰(feng)、調(diao)頻和(he)事故(gu)備(bei)用(yong)任務,這(zhe)樣就(jiu)增(zeng)(zeng)加了(le)機組(zu)啟動(dong)、停機次數(shu),致使水輪機部(bu)(bu)件(jian)(jian)動(dong)載荷增(zeng)(zeng)加,運行(xing)(xing)條件(jian)(jian)變得苛刻,對那些設備(bei)陳舊(jiu)的(de)(de)老(lao)電(dian)(dian)(dian)(dian)(dian)站(zhan),擔負(fu)這(zhe)樣任務顯然力(li)(li)不(bu)從心(xin)。同(tong)時,近幾(ji)年(nian)(nian)大電(dian)(dian)(dian)(dian)(dian)網對地方電(dian)(dian)(dian)(dian)(dian)網實行(xing)(xing)峰(feng)谷(gu)差(cha)價和(he)峰(feng)電(dian)(dian)(dian)(dian)(dian)超計劃加價政策,讓電(dian)(dian)(dian)(dian)(dian)網中調(diao)節性能(neng)較好的(de)(de)水電(dian)(dian)(dian)(dian)(dian)站(zhan)實行(xing)(xing)頂峰(feng)發(fa)電(dian)(dian)(dian)(dian)(dian),多發(fa)電(dian)(dian)(dian)(dian)(dian)必將會(hui)顯著(zhu)提(ti)高地方電(dian)(dian)(dian)(dian)(dian)網的(de)(de)負(fu)荷率(lv)(lv)(lv)和(he)經濟效益。


2水輪機轉輪改型(xing)的必要性(xing)和可行性(xing)


2.1水輪(lun)機(ji)轉(zhuan)輪(lun)改型的(de)必要性


從我國(guo)水電事業的發展(zhan)現狀來看,大批水電站(zhan)存在的主要(yao)問題(ti)及產生的嚴(yan)重后果主要(yao)是長期以來水輪機轉輪的設計(ji)制(zhi)造與使用條件相脫(tuo)節,主要(yao)表現在下面幾個方(fang)面[2]:


(1)水(shui)輪(lun)機(ji)轉輪(lun)效(xiao)率(lv)(lv)低。水(shui)輪(lun)機(ji)效(xiao)率(lv)(lv)是水(shui)輪(lun)機(ji)性能(neng)的重要指標(biao),據統(tong)計從50年代(dai)至今,水(shui)輪(lun)機(ji)效(xiao)率(lv)(lv)每10年提高一個(ge)百分點,我國有一大批機(ji)組水(shui)輪(lun)機(ji)轉輪(lun)系國內(nei)50、60年代(dai)產品(pin),與90年代(dai)國內(nei)外先(xian)進轉輪(lun)相比(bi),差(cha)距很(hen)大,真機(ji)效(xiao)率(lv)(lv)約低2%~5%以上。造(zao)成(cheng)可利用能(neng)源的巨大浪費。


(2)水輪(lun)(lun)機(ji)與水輪(lun)(lun)發(fa)(fa)電機(ji)選型不合理。“六五”以前安裝的水輪(lun)(lun)發(fa)(fa)電機(ji)組,由于設計條件限(xian)(xian)制(zhi),有(you)些(xie)電站(zhan)選擇水輪(lun)(lun)機(ji)與發(fa)(fa)電機(ji)偏(pian)于保守,使水能不能充分(fen)利(li)用,有(you)些(xie)電站(zhan)選擇水輪(lun)(lun)機(ji)與發(fa)(fa)電機(ji)容量匹配不當,從而大大限(xian)(xian)制(zhi)了機(ji)組出(chu)力。


(3)水(shui)輪(lun)機(ji)(ji)運行可靠性差。水(shui)輪(lun)機(ji)(ji)受當時設(she)計、制造(zao)水(shui)平限(xian)制,水(shui)輪(lun)機(ji)(ji)抗(kang)空(kong)化、抗(kang)磨(mo)損(sun)、抗(kang)振(zhen)動(dong)性能差,經幾(ji)十年運行,一些機(ji)(ji)組空(kong)化、磨(mo)損(sun)、振(zhen)動(dong)嚴重,運行條件惡(e)劣、事故(gu)隱(yin)患(huan)不斷增加。嚴重影響水(shui)輪(lun)機(ji)(ji)的(de)可靠運行。


(4)自然條(tiao)件(jian)的(de)(de)變(bian)化。近年來(lai)隨著(zhu)經濟的(de)(de)發展(zhan),有(you)些電(dian)站(zhan)(zhan)的(de)(de)上(shang)游(you)大力發展(zhan)耗(hao)水(shui)量較大的(de)(de)農業企業,工農業用水(shui)量突(tu)飛(fei)猛進。另外,隨著(zhu)人們生(sheng)活質(zhi)量的(de)(de)提高,生(sheng)活用水(shui)、環(huan)境用水(shui)、生(sheng)態用水(shui)等(deng)過去(qu)設計(ji)電(dian)站(zhan)(zhan)時忽(hu)略的(de)(de)部(bu)(bu)分消(xiao)耗(hao)也一(yi)天(tian)(tian)比(bi)一(yi)天(tian)(tian)增多。這樣部(bu)(bu)分水(shui)輪發電(dian)機(ji)組經幾十年投運(yun)(yun),上(shang)、下游(you)水(shui)位已(yi)發生(sheng)較大變(bian)化,原(yuan)有(you)轉輪運(yun)(yun)行已(yi)大大偏(pian)離設計(ji)工況,甚至無法(fa)正常運(yun)(yun)行。


綜(zong)上所述,80年代以前建(jian)設(she)的(de)(de)(de)一大批電(dian)站,由于機電(dian)設(she)備落后,技術老(lao)(lao)化(hua)(hua),機組設(she)計(ji)水(shui)(shui)(shui)平低,制造工藝(yi)差(cha),技術參數低。以及部件老(lao)(lao)化(hua)(hua)機組出力受阻(zu)和(he)自然條件的(de)(de)(de)變化(hua)(hua),已(yi)不能充(chong)分利用(yong)已(yi)開發的(de)(de)(de)水(shui)(shui)(shui)力資源(yuan),從而造成水(shui)(shui)(shui)力資源(yuan)的(de)(de)(de)再度浪費。再加上電(dian)網調峰的(de)(de)(de)迫(po)切需要。如何提高已(yi)開發的(de)(de)(de)水(shui)(shui)(shui)力資源(yuan)的(de)(de)(de)經濟效益和(he)社(she)會效益成為(wei)許多老(lao)(lao)水(shui)(shui)(shui)電(dian)廠面臨(lin)的(de)(de)(de)重大課(ke)題。


眾(zhong)所周知(zhi),水(shui)輪(lun)機轉輪(lun)水(shui)電(dian)站(zhan)的(de)(de)核心設備。水(shui)輪(lun)機的(de)(de)水(shui)力性(xing)能(neng)(neng)、振動與空化主要取決于轉輪(lun)性(xing)能(neng)(neng),轉輪(lun)性(xing)能(neng)(neng)的(de)(de)優劣對(dui)合理開發利用水(shui)能(neng)(neng)、保證電(dian)網可靠性(xing)方面(mian)有著巨大(da)影響。因(yin)此,對(dui)老的(de)(de)水(shui)輪(lun)機轉輪(lun)的(de)(de)更新改(gai)造勢在(zai)必行(xing)。通過對(dui)水(shui)輪(lun)機轉輪(lun)的(de)(de)改(gai)型,可提高機組效率,增加(jia)電(dian)站(zhan)容量,改(gai)善機組運行(xing)的(de)(de)安全穩(wen)定性(xing)。


2.2水輪(lun)機轉輪(lun)改型(xing)的可(ke)行性


首(shou)先,從經濟的角度分析,開發新(xin)電站(zhan)投資大(da)、周期長(chang),而進行水輪機轉(zhuan)輪的增(zeng)容改造(zao)由于(yu)不需(xu)要(yao)再建(jian)大(da)壩等水工建(jian)筑物,故投資很少(shao),見(jian)效(xiao)很快,經濟效(xiao)益很高。一般(ban)認為,對老電站(zhan)的增(zeng)容改造(zao)其(qi)單位(wei)千瓦(wa)投資要(yao)比新(xin)建(jian)電站(zhan)低2/3以上[3]。


因此(ci),水電站水輪(lun)機(ji)轉輪(lun)的改型(xing)是(shi)一項投(tou)入少產出多(duo)效益顯著的項目,是(shi)提高水電站運(yun)行(xing)可靠(kao)性和(he)經(jing)濟性的最(zui)主要方(fang)向(xiang),已成為許多(duo)國家解決能源短缺問題的手(shou)段(duan)之一。


其(qi)次(ci),從技(ji)術(shu)上來說,近年來計(ji)算機與(yu)計(ji)算技(ji)術(shu)、流體機械三維流動分(fen)析(xi)與(yu)設計(ji)理論、通訊與(yu)傳感器技(ji)術(shu)、現(xian)(xian)代控制理論和機械加工技(ji)術(shu)等都已取得了很大(da)的(de)進步。使得現(xian)(xian)代轉輪的(de)設計(ji)、測試(shi)和制造方面都取得了長足的(de)進步。這些新的(de)技(ji)術(shu)主要表現(xian)(xian)在(zai):


(1)數值模擬技術。五(wu)六十年代(dai),混流(liu)式轉(zhuan)輪(lun)的(de)(de)設計基礎是本世紀初羅倫(lun)茲提(ti)出(chu)的(de)(de)通流(liu)理(li)論,即假定轉(zhuan)輪(lun)中的(de)(de)葉片數無窮多,無限薄,這(zhe)樣將三維(wei)流(liu)動(dong)簡化成(cheng)軸對(dui)稱流(liu)動(dong)。從(cong)80年代(dai)以后,隨著計算(suan)(suan)機技術和計算(suan)(suan)流(liu)體動(dong)力學的(de)(de)迅速發(fa)(fa)展,水(shui)力機械過流(liu)部件的(de)(de)三維(wei)流(liu)動(dong)分析、三維(wei)設計和優化算(suan)(suan)法都有(you)了(le)長足的(de)(de)發(fa)(fa)展,已成(cheng)為過流(liu)部件水(shui)力設計與流(liu)動(dong)分析的(de)(de)重要(yao)工具。目前(qian),僅在水(shui)輪(lun)機研(yan)究領域就有(you)清華、哈電和東方廠(chang)等(deng)國(guo)內近(jin)十家單位引進了(le)先進的(de)(de)CFD分析軟(ruan)件。


如(ru)哈電(dian),利用(yong)(yong)CFD分析(xi)軟件(jian)進行模型轉(zhuan)輪(lun)開(kai)發,完(wan)成(cheng)了三峽(xia)右岸轉(zhuan)輪(lun)的轉(zhuan)化設(she)計(ji),對豐滿(man)、新安(an)江、丹江口、東江、烏溪江等一批老(lao)電(dian)站改造項目進行數(shu)值模擬(ni)和(he)優化,完(wan)成(cheng)了洛(luo)溪渡、水布埡、小灣、龍灘、公伯峽(xia)等電(dian)站水輪(lun)機的水力(li)設(she)計(ji)。東方廠利用(yong)(yong)CFD技術(shu)開(kai)發出福堂(tang)電(dian)站用(yong)(yong)D307模型轉(zhuan)輪(lun),其最高(gao)效率(lv)為(wei)(wei)94.43%。空(kong)(kong)化性(xing)能也(ye)很高(gao),其空(kong)(kong)化系數(shu)δ=0.047,飛逸轉(zhuan)速特性(xing)最大為(wei)(wei)106.4r/min,最大壓力(li)脈動混頻雙振幅值為(wei)(wei)5.5%。


另外,西安理工大學從80年代后期開始進行水(shui)(shui)輪(lun)(lun)機(ji)通流部件的(de)反問(wen)(wen)題(ti)(ti)研究[4],先(xian)后提出并建(jian)立(li)了(le)(le)基于S1流面(mian)反問(wen)(wen)題(ti)(ti)計(ji)算(suan)的(de)準(zhun)三維設(she)(she)計(ji)模(mo)型和方(fang)法(fa)、基于S2流面(mian)反問(wen)(wen)題(ti)(ti)計(ji)算(suan)的(de)準(zhun)三維設(she)(she)計(ji)模(mo)型和方(fang)法(fa)、基于混(hun)合譜方(fang)法(fa)的(de)全三維有(you)(you)旋流動的(de)反問(wen)(wen)題(ti)(ti)計(ji)算(suan)模(mo)型和方(fang)法(fa)。近年來,在三維粘性流設(she)(she)計(ji)模(mo)型的(de)基礎上,又實現了(le)(le)設(she)(she)計(ji)方(fang)案的(de)計(ji)算(suan)機(ji)自尋優(you),達到(dao)了(le)(le)根據廠站(zhan)的(de)實際水(shui)(shui)力參數進行“量體載衣”式的(de)設(she)(she)計(ji),取得了(le)(le)水(shui)(shui)力機(ji)械(xie)轉輪(lun)(lun)設(she)(she)計(ji)方(fang)法(fa)的(de)重大突破。到(dao)目前為(wei)止,用該模(mo)型已先(xian)后為(wei)有(you)(you)關電站(zhan)、多家(jia)水(shui)(shui)輪(lun)(lun)機(ji)廠和有(you)(you)關研究單位的(de)幾十臺(tai)水(shui)(shui)輪(lun)(lun)機(ji)轉輪(lun)(lun)進行了(le)(le)改型設(she)(she)計(ji),全部達到(dao)了(le)(le)用戶提出的(de)改造目標。


這種針對(dui)某一電(dian)站進行(xing)專門設計與制造的(de)(de)水(shui)輪機選型(xing)方法,可以保證讓每一個(ge)電(dian)站都(dou)可以選出適合(he)自己電(dian)站條件的(de)(de)最(zui)優(you)水(shui)輪機型(xing)式,從而(er)達(da)到最(zui)佳(jia)運(yun)(yun)行(xing)效果,取(qu)得最(zui)大經(jing)濟效益。通過(guo)采用(yong)先(xian)進的(de)(de)計算機數(shu)值模擬技術(shu)對(dui)水(shui)輪機轉輪進行(xing)增容改(gai)(gai)造,具有低投入、高產出、見效快的(de)(de)特(te)點(dian)。在改(gai)(gai)善運(yun)(yun)行(xing)性能的(de)(de)同時(shi)(shi)減少(shao)了運(yun)(yun)行(xing)及(ji)維修費用(yong)、減少(shao)了機組(zu)的(de)(de)停機時(shi)(shi)間,使(shi)電(dian)廠費用(yong)降低并盡(jin)快受益。


(2)模型測(ce)(ce)試(shi)技(ji)(ji)(ji)術。當前流體(ti)機械(xie)測(ce)(ce)試(shi)技(ji)(ji)(ji)術發展迅速,諸如(ru)壓力測(ce)(ce)量(liang)技(ji)(ji)(ji)術、流量(liang)測(ce)(ce)量(liang)技(ji)(ji)(ji)術和(he)粒子圖(tu)像(xiang)(xiang)測(ce)(ce)速技(ji)(ji)(ji)術有較大(da)的(de)(de)提(ti)(ti)升,多媒體(ti)技(ji)(ji)(ji)術和(he)計算機網(wang)絡技(ji)(ji)(ji)術進一(yi)步(bu)應用(yong)(yong)到流體(ti)機械(xie)測(ce)(ce)試(shi)系(xi)統中。總之,以計算機為(wei)(wei)核心(xin)的(de)(de)自動(dong)測(ce)(ce)試(shi)系(xi)統已成為(wei)(wei)現(xian)代測(ce)(ce)試(shi)系(xi)統的(de)(de)一(yi)個特點和(he)通用(yong)(yong)形式。國內的(de)(de)哈(ha)電(dian)、東方、雙富等廠家和(he)清華(hua)、河海、水(shui)(shui)科(ke)院(yuan)等科(ke)研(yan)院(yuan)校都建設或(huo)對原水(shui)(shui)輪(lun)機模型試(shi)驗臺(tai)的(de)(de)電(dian)氣、測(ce)(ce)試(shi)系(xi)統進行了全面(mian)的(de)(de)改造。其(qi)綜合(he)測(ce)(ce)試(shi)精度、運行穩定(ding)(ding)性(xing)和(he)重復精度大(da)大(da)提(ti)(ti)高。目前,全國已有5座通過部級鑒定(ding)(ding)的(de)(de)現(xian)代化試(shi)驗臺(tai),其(qi)效率綜合(he)試(shi)驗誤差(cha)在±0.25%~±0.3%,為(wei)(wei)水(shui)(shui)輪(lun)機模型試(shi)驗和(he)電(dian)站改造驗證(zheng)研(yan)究提(ti)(ti)供(gong)了良好(hao)的(de)(de)條件。如(ru)哈(ha)電(dian)研(yan)制成功(gong)了轉輪(lun)內部流態(tai)觀(guan)察(cha)(cha)成像(xiang)(xiang)系(xi)統[5],可(ke)通過光纖(xian)內窺鏡(jing)和(he)攝像(xiang)(xiang)頭采集(ji)轉輪(lun)進口(kou)(kou)處的(de)(de)脫流、葉道渦、空化和(he)出口(kou)(kou)處的(de)(de)空化、渦帶的(de)(de)信息(xi),驗證(zheng)CFD的(de)(de)分析(xi)結果。也可(ke)通過觀(guan)察(cha)(cha)轉輪(lun)在各工況的(de)(de)流態(tai),為(wei)(wei)改型設計提(ti)(ti)供(gong)依據。


(3)剛(gang)強度(du)(du)計(ji)算技術(shu)[5]。水輪機轉輪不僅(jin)要(yao)有(you)好的(de)水力(li)性能,還(huan)(huan)應具(ju)備(bei)高的(de)剛(gang)強度(du)(du)性能,這樣才能保證機組高效安(an)全(quan)地運行。因(yin)此(ci)對轉輪的(de)剛(gang)強度(du)(du)計(ji)算以(yi)及計(ji)算的(de)準確(que)性尤為(wei)(wei)(wei)重(zhong)要(yao)。傳統的(de)設(she)計(ji)方法(fa)采用簡(jian)單的(de)材料力(li)學(xue)理論將(jiang)葉片(pian)作為(wei)(wei)(wei)一(yi)懸臂(bei)梁在全(quan)水頭均壓下(xia)計(ji)算根部應力(li),計(ji)算結果與(yu)實際有(you)較(jiao)大出入,或通過模型試(shi)驗和(he)電(dian)站實測來為(wei)(wei)(wei)設(she)計(ji)者提(ti)供參(can)考。而(er)且還(huan)(huan)無法(fa)計(ji)算葉片(pian)的(de)靜(jing)位(wei)移和(he)固有(you)頻(pin)率。近(jin)年(nian)來隨著(zhu)有(you)限元的(de)發展(zhan),機械(xie)構件的(de)剛(gang)強度(du)(du)計(ji)算技術(shu)有(you)了很大的(de)提(ti)高。用計(ji)算機模擬技術(shu)代(dai)替模型試(shi)驗和(he)電(dian)站實測以(yi)成為(wei)(wei)(wei)可(ke)能。目前以(yi)ANSYS和(he)IDEAS為(wei)(wei)(wei)代(dai)表(biao)的(de)一(yi)大批大型有(you)限元結構分析計(ji)算軟件在轉輪剛(gang)強度(du)(du)計(ji)算中得到


了廣泛的應(ying)用,實現了水力與強度的交(jiao)互(hu)式設計(ji)(ji),計(ji)(ji)算結(jie)果更為準(zhun)確,葉片應(ying)力狀況(kuang)也(ye)更趨合理。同時采用有限元邊界元法相結(jie)合來計(ji)(ji)算過流部件的流固(gu)耦(ou)合振動(dong),由于考慮了結(jie)構在流體中(zhong)振動(dong)的附連水質量,可用計(ji)(ji)算來估算結(jie)構在水中(zhong)的固(gu)有頻率(lv),這種方法可在改造項目中(zhong)對(dui)機組的穩(wen)定(ding)性(xing)進行預測(ce)。


(4)葉(xie)(xie)(xie)片(pian)(pian)(pian)模(mo)(mo)壓成(cheng)形技(ji)術。水輪機轉(zhuan)輪是(shi)水輪機的(de)心(xin)(xin)臟,因此它的(de)制(zhi)造(zao)質量(liang)至關重要。直接影響著轉(zhuan)輪的(de)效率(lv)(lv)、抗(kang)空化性(xing)能和運行穩定性(xing)。過去大(da)多(duo)采用鑄(zhu)造(zao)方(fang)法制(zhi)造(zao)葉(xie)(xie)(xie)片(pian)(pian)(pian),打(da)磨(mo)光(guang)滑后與上(shang)冠、下環拼焊(han)。該工(gong)(gong)藝方(fang)法有很多(duo)缺點(dian):型(xing)(xing)線偏差(cha)大(da)、表面粗(cu)糙、打(da)磨(mo)廢工(gong)(gong)、抗(kang)空化性(xing)能差(cha),并(bing)且鑄(zhu)造(zao)的(de)葉(xie)(xie)(xie)片(pian)(pian)(pian)帶有鑄(zhu)造(zao)缺陷,使得(de)(de)葉(xie)(xie)(xie)片(pian)(pian)(pian)使用性(xing)能變壞,對于大(da)型(xing)(xing)葉(xie)(xie)(xie)片(pian)(pian)(pian),葉(xie)(xie)(xie)型(xing)(xing)精(jing)確度更難控(kong)制(zhi),最(zui)終也不易(yi)達到要求。近幾年來,模(mo)(mo)壓成(cheng)型(xing)(xing)技(ji)術廣泛用于水輪機轉(zhuan)輪葉(xie)(xie)(xie)片(pian)(pian)(pian)制(zhi)造(zao),它是(shi)一項(xiang)可以(yi)獲得(de)(de)葉(xie)(xie)(xie)型(xing)(xing)準確、鏟磨(mo)量(liang)小、價格適(shi)中(zhong)、生(sheng)產周(zhou)期(qi)較短的(de)轉(zhuan)輪葉(xie)(xie)(xie)片(pian)(pian)(pian)制(zhi)造(zao)技(ji)術。其方(fang)法是(shi)將葉(xie)(xie)(xie)片(pian)(pian)(pian)母材(cai)進(jin)行初(chu)步加工(gong)(gong),然后放(fang)在用數控(kong)機床銑好的(de)壓模(mo)(mo)內(nei)用壓力機壓型(xing)(xing),最(zui)后做局部修(xiu)磨(mo)。這(zhe)種(zhong)方(fang)式制(zhi)成(cheng)的(de)葉(xie)(xie)(xie)片(pian)(pian)(pian)型(xing)(xing)線好,材(cai)質好,抗(kang)空化磨(mo)損(sun)性(xing)能強,效率(lv)(lv)也易(yi)得(de)(de)到保證。如哈電(dian)應用IDEAS和DEFORM-3D兩(liang)個有限元(yuan)軟件開(kai)發了動態(tai)計(ji)算模(mo)(mo)壓葉(xie)(xie)(xie)片(pian)(pian)(pian)中(zhong)心(xin)(xin)和壓力噸位的(de)計(ji)算方(fang)法,已獲得(de)(de)了成(cheng)功。


(5)葉(xie)(xie)片數(shu)(shu)控(kong)(kong)加工(gong)(gong)(gong)(gong)(gong)(gong)技(ji)術(shu)。對于葉(xie)(xie)片的(de)(de)(de)(de)(de)加工(gong)(gong)(gong)(gong)(gong)(gong)過(guo)(guo)去采用(yong)(yong)(yong)“立體樣板(ban)-鏟磨”工(gong)(gong)(gong)(gong)(gong)(gong)藝,這(zhe)是一(yi)種(zhong)(zhong)通(tong)過(guo)(guo)投入大(da)量手工(gong)(gong)(gong)(gong)(gong)(gong)勞動(dong)力,依據(ju)立體樣板(ban)作(zuo)(zuo)(zuo)為(wei)測(ce)量工(gong)(gong)(gong)(gong)(gong)(gong)具,把鑄件毛坯(pi)變成(cheng)葉(xie)(xie)片成(cheng)品的(de)(de)(de)(de)(de)工(gong)(gong)(gong)(gong)(gong)(gong)藝。根(gen)據(ju)文獻[6],使(shi)(shi)用(yong)(yong)(yong)這(zhe)種(zhong)(zhong)加工(gong)(gong)(gong)(gong)(gong)(gong)工(gong)(gong)(gong)(gong)(gong)(gong)藝存在著測(ce)量精度差、使(shi)(shi)用(yong)(yong)(yong)操作(zuo)(zuo)(zuo)困難和(he)(he)費用(yong)(yong)(yong)大(da)的(de)(de)(de)(de)(de)三大(da)致命缺(que)點(dian)。近(jin)年來(lai)(lai),國內外各(ge)(ge)水(shui)輪機制造(zao)廠家已(yi)取(qu)(qu)消了(le)(le)傳(chuan)統(tong)的(de)(de)(de)(de)(de)立體樣板(ban),采用(yong)(yong)(yong)數(shu)(shu)控(kong)(kong)加工(gong)(gong)(gong)(gong)(gong)(gong)技(ji)術(shu),它是一(yi)種(zhong)(zhong)通(tong)過(guo)(guo)計算(suan)機系(xi)統(tong)的(de)(de)(de)(de)(de)軟件控(kong)(kong)制機床自動(dong)操作(zuo)(zuo)(zuo)完(wan)成(cheng)的(de)(de)(de)(de)(de)一(yi)種(zhong)(zhong)理(li)(li)想的(de)(de)(de)(de)(de)加工(gong)(gong)(gong)(gong)(gong)(gong)工(gong)(gong)(gong)(gong)(gong)(gong)藝。由于它能把葉(xie)(xie)片的(de)(de)(de)(de)(de)理(li)(li)論曲(qu)面圖形通(tong)過(guo)(guo)數(shu)(shu)據(ju)輸(shu)出準確無誤地傳(chuan)送到執行指令的(de)(de)(de)(de)(de)操作(zuo)(zuo)(zuo)機構(gou)上(shang),解(jie)決(jue)了(le)(le)葉(xie)(xie)片測(ce)量與(yu)理(li)(li)論位置的(de)(de)(de)(de)(de)自動(dong)找正(zheng)問(wen)題(ti)和(he)(he)測(ce)點(dian)加工(gong)(gong)(gong)(gong)(gong)(gong)余(yu)量的(de)(de)(de)(de)(de)自動(dong)計算(suan)問(wen)題(ti),使(shi)(shi)大(da)型水(shui)輪機的(de)(de)(de)(de)(de)葉(xie)(xie)片制造(zao)精度較(jiao)傳(chuan)統(tong)立體樣板(ban)工(gong)(gong)(gong)(gong)(gong)(gong)藝有了(le)(le)較(jiao)大(da)提(ti)高。如劉家峽(xia)2#轉輪和(he)(he)天生橋的(de)(de)(de)(de)(de)5#、6#轉輪都是采用(yong)(yong)(yong)數(shu)(shu)控(kong)(kong)加工(gong)(gong)(gong)(gong)(gong)(gong)。再者,從工(gong)(gong)(gong)(gong)(gong)(gong)程應用(yong)(yong)(yong)方面來(lai)(lai)說,近(jin)年來(lai)(lai),老電(dian)(dian)(dian)站機組的(de)(de)(de)(de)(de)技(ji)術(shu)改(gai)造(zao)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)(zuo)已(yi)引起了(le)(le)世界各(ge)(ge)國的(de)(de)(de)(de)(de)普(pu)遍(bian)關注,尤其在一(yi)些水(shui)力資源開(kai)發程度較(jiao)高的(de)(de)(de)(de)(de)國家,更為(wei)重視。我(wo)(wo)國的(de)(de)(de)(de)(de)電(dian)(dian)(dian)站更新改(gai)造(zao)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)(zuo)與(yu)國外先進國家相比雖然起步較(jiao)晚。但也于80年代初(chu)開(kai)始探索性(xing)的(de)(de)(de)(de)(de)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)(zuo)。20年來(lai)(lai),各(ge)(ge)類水(shui)電(dian)(dian)(dian)站的(de)(de)(de)(de)(de)技(ji)術(shu)改(gai)造(zao)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)(zuo)已(yi)取(qu)(qu)得了(le)(le)不少的(de)(de)(de)(de)(de)成(cheng)績(ji)和(he)(he)經驗,為(wei)各(ge)(ge)電(dian)(dian)(dian)廠和(he)(he)科(ke)研單位培養了(le)(le)大(da)批技(ji)術(shu)人(ren)員和(he)(he)技(ji)術(shu)工(gong)(gong)(gong)(gong)(gong)(gong)人(ren),從而(er)為(wei)我(wo)(wo)國各(ge)(ge)電(dian)(dian)(dian)廠的(de)(de)(de)(de)(de)增容(rong)改(gai)造(zao)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)(zuo)奠定了(le)(le)基礎,使(shi)(shi)各(ge)(ge)水(shui)電(dian)(dian)(dian)站的(de)(de)(de)(de)(de)技(ji)術(shu)改(gai)造(zao)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)(zuo)的(de)(de)(de)(de)(de)順利完(wan)成(cheng)成(cheng)為(wei)可能。


3結論


開發新(xin)電(dian)(dian)站(zhan)(zhan)(zhan)投資(zi)大、周(zhou)期長,而老電(dian)(dian)站(zhan)(zhan)(zhan)增容更新(xin)改(gai)(gai)(gai)(gai)(gai)造(zao)由于(yu)不(bu)需(xu)要再建大壩等水(shui)(shui)(shui)(shui)工建筑物(wu),故投資(zi)少、周(zhou)期短、收益大。可(ke)見,水(shui)(shui)(shui)(shui)電(dian)(dian)站(zhan)(zhan)(zhan)更新(xin)改(gai)(gai)(gai)(gai)(gai)造(zao)已成為許(xu)多國家解決能(neng)(neng)源短缺的(de)(de)(de)(de)重要手段之(zhi)一,而水(shui)(shui)(shui)(shui)輪(lun)機(ji)(ji)(ji)(ji)轉輪(lun)是(shi)水(shui)(shui)(shui)(shui)電(dian)(dian)站(zhan)(zhan)(zhan)的(de)(de)(de)(de)主要設備之(zhi)一,水(shui)(shui)(shui)(shui)輪(lun)機(ji)(ji)(ji)(ji)轉輪(lun)性(xing)(xing)(xing)能(neng)(neng)的(de)(de)(de)(de)優劣(lie)對(dui)合(he)理開發利(li)用(yong)水(shui)(shui)(shui)(shui)能(neng)(neng)、提高水(shui)(shui)(shui)(shui)電(dian)(dian)站(zhan)(zhan)(zhan)運行(xing)(xing)可(ke)靠(kao)性(xing)(xing)(xing)和(he)(he)經濟性(xing)(xing)(xing)、保證電(dian)(dian)網可(ke)靠(kao)性(xing)(xing)(xing)方面有著巨大影響。所(suo)以,水(shui)(shui)(shui)(shui)電(dian)(dian)站(zhan)(zhan)(zhan)水(shui)(shui)(shui)(shui)輪(lun)機(ji)(ji)(ji)(ji)轉輪(lun)改(gai)(gai)(gai)(gai)(gai)型(xing)(xing)設計已成為水(shui)(shui)(shui)(shui)電(dian)(dian)站(zhan)(zhan)(zhan)更新(xin)改(gai)(gai)(gai)(gai)(gai)造(zao)的(de)(de)(de)(de)主要任務(wu)與關鍵途(tu)徑之(zhi)一。與此(ci)同時,現(xian)代(dai)計算機(ji)(ji)(ji)(ji)數值模擬技(ji)術、模型(xing)(xing)測試技(ji)術、剛強度計算技(ji)術和(he)(he)制(zhi)造(zao)技(ji)術的(de)(de)(de)(de)不(bu)斷進步,為水(shui)(shui)(shui)(shui)輪(lun)機(ji)(ji)(ji)(ji)轉輪(lun)的(de)(de)(de)(de)改(gai)(gai)(gai)(gai)(gai)型(xing)(xing)設計創(chuang)造(zao)了(le)條件。因此(ci),我們應充(chong)分(fen)利(li)用(yong)現(xian)代(dai)科學技(ji)術成果,結(jie)合(he)我國八十(shi)年代(dai)之(zhi)前建造(zao)的(de)(de)(de)(de)中(zhong)小(xiao)型(xing)(xing)水(shui)(shui)(shui)(shui)電(dian)(dian)站(zhan)(zhan)(zhan)的(de)(de)(de)(de)實際情況進行(xing)(xing)機(ji)(ji)(ji)(ji)組特別是(shi)水(shui)(shui)(shui)(shui)輪(lun)機(ji)(ji)(ji)(ji)的(de)(de)(de)(de)技(ji)術改(gai)(gai)(gai)(gai)(gai)造(zao)。確保水(shui)(shui)(shui)(shui)輪(lun)機(ji)(ji)(ji)(ji)的(de)(de)(de)(de)高性(xing)(xing)(xing)能(neng)(neng)、高質量(liang)和(he)(he)安(an)全可(ke)靠(kao)運行(xing)(xing)。
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