摘要: 以軸流式核主泵為研究對(duì)象,采用數(shù)值模擬和試驗(yàn)驗(yàn)證相結(jié)合的方法,計(jì)算模型為SST k-ω湍流模型,重點(diǎn)選取了0.9Q,1.0Q與1.1Q工況,對(duì)軸流式核主泵內(nèi)部流動(dòng)特性進(jìn)行分析,結(jié)合性能試驗(yàn)臺(tái)完成試驗(yàn)驗(yàn)證.在分析計(jì)算結(jié)果時(shí),重點(diǎn)考察了泵出口中心截面的速度流線圖和速度分布云圖,以此來深入探討泵在不同流量條件下內(nèi)部流動(dòng)模式的差異及其演變趨勢(shì);提取葉輪與導(dǎo)葉葉片通道回轉(zhuǎn)面的壓力速度云圖、葉輪葉片與導(dǎo)葉葉片的壓力載荷曲線,對(duì)比分析不同流量下泵內(nèi)部流動(dòng)結(jié)構(gòu)及其變化規(guī)律,進(jìn)一步揭示葉輪和導(dǎo)葉內(nèi)的流動(dòng)分布及能量轉(zhuǎn)換機(jī)制.通過試驗(yàn)對(duì)數(shù)值計(jì)算開展了對(duì)比驗(yàn)證,計(jì)算結(jié)果與試驗(yàn)結(jié)果基本吻合,揚(yáng)程模擬值比試驗(yàn)值低3.87%,效率模擬值比試驗(yàn)值低1.94%.本研究深入揭示了軸流式核主泵內(nèi)部流動(dòng)特性,對(duì)充分認(rèn)識(shí)核主泵水力結(jié)構(gòu)與內(nèi)部流動(dòng)關(guān)聯(lián)性至關(guān)重要,為軸流式核主泵的設(shè)計(jì)和性能優(yōu)化提供參考依據(jù).
關(guān)鍵詞: 軸流式核主泵;內(nèi)部流動(dòng)特性;數(shù)值計(jì)算與試驗(yàn);湍流模型
中圖分類號(hào): S277.9 文獻(xiàn)標(biāo)志碼: A 文章編號(hào): 1674-8530(2024)12-1189-07
DOI:10.3969/j.issn.1674-8530.23.0137
蔡龍,徐源,龍?jiān)?,? 軸流式核主泵內(nèi)部流動(dòng)特性數(shù)值計(jì)算與試驗(yàn)[J]. 排灌機(jī)械工程學(xué)報(bào),2024,42(12):1189-1195,1210.
CAI Long, XU Yuan, LONG Yun, et al. Numerical simulation and experiment on internal flow characteristics of axial-flow nuclear reactor coolant pump[J]. Journal of drainage and irrigation machinery engineering (JDIME), 2024, 42(12):1189-1195,1210. (in Chinese)
Numerical simulation and experiment on internal flow
characteristics of axial-flow nuclear reactor coolant pump
CAI Long1,2, XU Yuan3, LONG Yun3*, ZHOU Zhen3, ZHU Rongsheng3, YUAN Shouqi3
(1. Harbin Electric Power Equipment Company Limited, Harbin, Heilongjiang 150060, China; 2. School of Materials Science and Engineering, Dalian University of Technology, Dalian, Liaoning 116024, China; 3. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China)
Abstract: An axial-flow nuclear reactor coolant pump was taken as the research object, and a method of employing a combination of numerical calculation and experimental research was adopted. The SST k-ω turbulence model was used, and 0.9Q, 1.0Q, and 1.1Q were selected as working conditions to analyze the internal flow characteristics of the axial-flow nuclear reactor coolant pump. The experimental verification was completed on the comprehensive performance test bench of the pump. When analyzing the calculation results, the velocity streamline diagram and velocity distribution cloud diagram of the center section of the pump outlet were examined in detail to explore the differences in the internal flow patterns and their evolution trends of the pump under different flow conditions. The pressure-velocity cloud diagrams of the rotating surfaces of the impeller and guide vane blade channels, and the blade pressure-load curves of the impeller blades and guide vane blades were extracted, and the internal flow structure and its changing law of the pump under different flow rates were compared and analyzed to further reveal the flow distribution and energy conversion mechanism inside the impeller and guide vanes. The numerical calculation was compared and verified through experiments. The calculated results are basically consistent with the experimental results. The head simulation value is 3.87% lower than the experimental value, and the efficiency simulation value is 1.94% lower than the experimental value. This research work deeply reveals the internal flow characteristics of the axial-flow nuclear reactor coolant pump, which is very important to fully understand the correlation between the hydraulic structure and internal flow of the nuclear reactor coolant pump, and provides a reference for the design and performance optimization of the axial-flow nuclear reactor coolant pump.
Key words: axial-flow nuclear reactor coolant pump;internal flow characteristics;numerical simulationand experiment;turbulence model
反應(yīng)堆冷卻劑泵(簡稱核主泵)是核電站中核反應(yīng)堆冷卻劑系統(tǒng)的核心組件之一.在中國核電發(fā)展規(guī)劃中,核主泵是重要的核心設(shè)備,但是在設(shè)計(jì)、制造和運(yùn)行過程中,核主泵也存在著一系列的問題[1-3].因此,為了提高核主泵的運(yùn)行性能和穩(wěn)定性,需要對(duì)核主泵進(jìn)行優(yōu)化設(shè)計(jì).目前國內(nèi)核主泵主要采用的是準(zhǔn)球形泵殼的混流泵,但隨著核電站設(shè)計(jì)功率的提高,對(duì)核主泵的流量要求越來越高,混流式核主泵在核反應(yīng)堆冷卻劑系統(tǒng)中不再是最佳選擇,而能夠提供大流量高斜率的軸流式核主泵將成為更好的選擇.因此,必須對(duì)軸流式核主泵內(nèi)部流動(dòng)特性進(jìn)行研究,用于進(jìn)一步優(yōu)化設(shè)計(jì)方案,提高核主泵工作效率、瞬態(tài)特性等關(guān)鍵指標(biāo).
針對(duì)傳統(tǒng)的全特性表達(dá)式只描述特定轉(zhuǎn)速下有限的流動(dòng)段的缺點(diǎn),ZHU等[4]采用歸一化方法處理全特性數(shù)據(jù),得到的歸一化曲線能夠完整、準(zhǔn)確地表達(dá)主反應(yīng)堆冷卻劑泵在任意轉(zhuǎn)速和全流量下的全特性.劉毅等[5]研究了時(shí)間步長對(duì)核主泵計(jì)算精度的影響,通過分析泵內(nèi)旋渦場分布特征,探討了時(shí)間步長的大小對(duì)核主泵內(nèi)復(fù)雜脈動(dòng)特征的解析精度.陳鑫[6]針對(duì)與“華龍一號(hào)”核主泵具有相同水力結(jié)構(gòu)形式的軸流式核主泵,研究和驗(yàn)證了其非定常流動(dòng)的數(shù)值模擬方法,提出了2種用于表征動(dòng)靜干涉作用的流場特征參數(shù),通過試驗(yàn)、理論分析和數(shù)值模擬相結(jié)合的方法,深入研究非穩(wěn)態(tài)流動(dòng)、動(dòng)靜干擾及激勵(lì)等特征.胡雷等[7]對(duì)1 000 MW軸流式核主泵5個(gè)不同溫度下相同流量點(diǎn)工況進(jìn)行數(shù)值模擬計(jì)算,并與試驗(yàn)值進(jìn)行對(duì)比,在核主泵試驗(yàn)的過程中,發(fā)現(xiàn)隨著溫度的升高,核主泵的揚(yáng)程逐漸升高.龍?jiān)频?sup>[8]對(duì)核主泵內(nèi)部流動(dòng)特性的現(xiàn)狀進(jìn)行了綜述調(diào)研,指出對(duì)核電站運(yùn)行中事故工況下的水動(dòng)力特性研究具有非常重要的意義.高波等[9]為了充分認(rèn)識(shí)核主泵內(nèi)部流動(dòng)的真實(shí)結(jié)構(gòu),采用一種非接觸式光學(xué)流場測量儀器(粒子圖像速度場儀)對(duì)泵內(nèi)流場進(jìn)行測量[9].JUNG等[10]首先通過試驗(yàn)獲得了小型模塊化反應(yīng)堆泵的同源曲線,然后通過計(jì)算流體力學(xué)(CFD)生成了同源曲線.LONG等[11-13]、SONG等[14-15]討論了非均勻來流對(duì)反應(yīng)堆冷卻劑泵水動(dòng)力、空化特性的影響.采用試驗(yàn)研究和數(shù)值模擬相結(jié)合的方法,對(duì)這些現(xiàn)象進(jìn)行了分析.倪丹等[16-17]基于LES模型模擬核主泵在設(shè)計(jì)工況下的非定常特性,分析了葉輪進(jìn)口處以及導(dǎo)葉接近出液管附近各流道內(nèi)的非定常流動(dòng)特性.PARK等[18]研究發(fā)現(xiàn),在全流量、全轉(zhuǎn)速范圍內(nèi),只要獲得恒定揚(yáng)程曲線,就可以在不增加水力試驗(yàn)的情況下獲得其他恒定揚(yáng)程曲線.WANG等[19]對(duì)轉(zhuǎn)子卡死事故下進(jìn)出口流量、轉(zhuǎn)速、扭矩、壓力波動(dòng)等瞬態(tài)指標(biāo)進(jìn)行了仿真研究.研究還發(fā)現(xiàn),在對(duì)純液體介質(zhì)進(jìn)行非定常流動(dòng)分析時(shí),采用雙向流固耦合方法模擬的反應(yīng)堆冷卻劑泵的揚(yáng)程平均值有所下降,耦合結(jié)果更接近真實(shí)試驗(yàn).王俊等[20]將混流式核主泵水力模型作為研究對(duì)象,在三維不可壓縮流體的N-S方程和RNG k-ε湍流模型的基礎(chǔ)上,采用流體計(jì)算,利用ANSYS Fluent軟件,對(duì)核主泵在不同工作條件下的三維湍流進(jìn)行了數(shù)值計(jì)算.
綜上,當(dāng)前對(duì)于新型軸流式核主泵內(nèi)部流動(dòng)特性的理解仍有待進(jìn)一步加深.文中運(yùn)用數(shù)值分析與試驗(yàn)測試相結(jié)合的方法,對(duì)軸流式核主泵在多種工作狀態(tài)下的內(nèi)部流動(dòng)形態(tài)及其水力響應(yīng)進(jìn)行詳細(xì)的對(duì)比研究.
1 軸流式核主泵數(shù)值計(jì)算
1.1 計(jì)算模型
根據(jù)軸流式核主泵的內(nèi)部流體動(dòng)力學(xué)特點(diǎn),選擇了以下幾個(gè)主要參數(shù):核主泵設(shè)計(jì)流量Q1=24 680.0 m3/h,轉(zhuǎn)速n1=1 485 r/min,揚(yáng)程H1=86.00 m;對(duì)應(yīng)模型泵設(shè)計(jì)參數(shù)為流量Q2=1 048.4 m3/h,轉(zhuǎn)速n2=1 485 r/min,揚(yáng)程H2=10.47 m,比轉(zhuǎn)數(shù)ns=502.5.依據(jù)軸流式核主泵的規(guī)格要求,界定了核心水力元件的基礎(chǔ)幾何尺寸.采用CFturbo軟件對(duì)該泵的葉輪和導(dǎo)葉進(jìn)行了多變量的建模設(shè)計(jì),同時(shí)利用三維建模工具對(duì)管道部分、泵體以及出水口的流體區(qū)域進(jìn)行了建模.所采用的計(jì)算模型基于設(shè)計(jì)原型泵.如圖1所示,軸流式核主泵的模擬區(qū)域劃分為4個(gè)主要部分,包括直管進(jìn)口段水體、葉輪水體、導(dǎo)葉水體和泵殼與出口段水體.計(jì)算所使用模型的葉輪進(jìn)口處內(nèi)徑為54.07 cm,外徑為141.23 cm,出口處內(nèi)徑為97.00 cm,外徑為155.96 cm;導(dǎo)葉進(jìn)口處內(nèi)徑為97.10 cm,外徑為155.96 cm,出口處直徑為187.50 cm.圖2為葉輪和導(dǎo)葉的計(jì)算模型.
CFD的控制方程主要包括連續(xù)方程、動(dòng)量方程及能量方程.由于研究對(duì)象為軸流式核主泵水力性能,因此能量方程不予考慮;泵內(nèi)流體介質(zhì)為不可壓縮流,其連續(xù)方程為
uxx+uyy+uzz=0,(1)
式中:ux,uy,uz分別為流體速度矢量在x,y,z方向上的分量.
不可壓縮流的動(dòng)量方程即N-S方程
ρDuiDt=ρfi-ρxi+μ2uixj·xj, i=1,2,3, (2)
式中:ρ為流體的密度;DuiDt為物質(zhì)導(dǎo)數(shù);ui為流體速度;t為時(shí)間;fi為單位體積流體受的外力;μ為動(dòng)力黏度;xi,xj為位移分量.
揚(yáng)程為單位重量的液體通過水泵后其能量的增值,文中采用H表示,工程中折算成被抽送液體的葉柱高度變化量,計(jì)算式為
H=pout-pinρg,(3)
式中:pout為出口處的總壓力;pin為入口處的總壓力;g為重力加速度.
水泵效率為水泵有效功率Ph與軸功率Ps的比值,一般用η表示,計(jì)算式為
η=PhPs=ρgQHPs,(4)
式中:Q為泵的流量;Ps=nT9 550, 其中,n為泵的轉(zhuǎn)速,r/m;T為泵的扭矩,N·m.
1.2 網(wǎng)格劃分
文中所用計(jì)算模型結(jié)構(gòu)參考了胡雷等[7]所使用的1 000 MW軸流式核主泵方法,選用的網(wǎng)格數(shù)量總量多于參考模型,為972萬,故提高了計(jì)算精度,更好地捕捉物理現(xiàn)象,并提高了收斂性.如圖3所示,葉輪網(wǎng)格數(shù)為212萬,導(dǎo)葉網(wǎng)格數(shù)為301萬,直管網(wǎng)格數(shù)為151萬,泵殼與出口段網(wǎng)格數(shù)為308萬.圖4展示了水力模型的整體網(wǎng)格劃分.
1.3 邊界條件設(shè)置
采用ANSYS CFX 2021 R1軟件對(duì)軸流式核主泵的流動(dòng)進(jìn)行數(shù)值計(jì)算.計(jì)算采用SST k-ω湍流模型,介質(zhì)為25 ℃的水,密度為997 kg/m3,動(dòng)力黏度為8.899×10-4 kg/(m·s).在模擬中,入口為質(zhì)量流量、出口為壓力的形式施加.泵體壁面采用無滑移邊界條件.葉輪區(qū)域設(shè)定為旋轉(zhuǎn)參考系,旋轉(zhuǎn)速度為1 485 r/min,葉片隨之旋轉(zhuǎn),而導(dǎo)葉、進(jìn)口段和泵殼則視為靜止.動(dòng)網(wǎng)格界面采用Frozen Rotor模型處理.在計(jì)算中,對(duì)流項(xiàng)離散格式選用了Upwind方案.
2 軸流式核主泵內(nèi)部流動(dòng)分析
軸流式核主泵的多功能性是其一大優(yōu)勢(shì),因此在設(shè)計(jì)過程中,不僅要考慮所設(shè)計(jì)的核主泵能在設(shè)計(jì)工況下實(shí)現(xiàn)長期穩(wěn)定的運(yùn)行,還需要在實(shí)際使用過程中能適應(yīng)多變復(fù)雜的工況.因此,深入理解泵在接近正常運(yùn)行工況時(shí)的內(nèi)部流動(dòng)特性對(duì)于科學(xué)的設(shè)計(jì)至關(guān)重要.為了評(píng)價(jià)軸流式核主泵的性能,文中基于計(jì)算數(shù)據(jù),選取了設(shè)計(jì)工況附近0.9Q,1.0Q和1.1Q這3種工況進(jìn)行內(nèi)部流動(dòng)特性分析.
2.1 整泵內(nèi)部流動(dòng)
圖5為0.9Q,1.0Q及1.1Q工況下水泵內(nèi)部流動(dòng)三維流線圖.從圖5可以看出,泵殼內(nèi)的流線存在一種螺旋形的擾動(dòng),隨著流量的增大,流動(dòng)擾動(dòng)加劇.3種工況下泵殼內(nèi)均觀察到明顯的低速渦流區(qū)域.
典型放大區(qū)域如圖6所示,它們形成的原因在于,泵殼的環(huán)形設(shè)計(jì)使得流過導(dǎo)葉后的流體匯聚受限,進(jìn)而導(dǎo)致該區(qū)域流速下降.同時(shí),由于泵殼出口處為高速流動(dòng),在導(dǎo)葉出口處,流速也較高,這種從高速到低速的流動(dòng)過渡會(huì)引起流體的不穩(wěn)定性,形成高速射流和脫落渦.脫落渦的存在對(duì)泵的性能有一定的影響,它會(huì)導(dǎo)致流體的能量損失和流動(dòng)的不穩(wěn)定性,從而降低泵的效率和性能.因此,在軸流式核主泵的設(shè)計(jì)和優(yōu)化中,需要考慮如何減小脫落渦的產(chǎn)生,以提高泵的效率和性能.
2.2 速度與流線分布
圖7為YZ軸截取的平面位置示意圖.圖8為泵殼與導(dǎo)葉的中心軸線截面上的速度流線圖.由圖8可以明顯觀察到導(dǎo)葉相鄰流道向泵殼流動(dòng)的區(qū)域出現(xiàn)了顯著的低速區(qū)域.流線的分布揭示了在3種不同的工況下,在這些低速區(qū)域都產(chǎn)生了明顯的大尺度旋渦.這種現(xiàn)象產(chǎn)生的原因是流體在離開導(dǎo)葉時(shí)具有較高的速度,并且受到泵殼的幾何結(jié)構(gòu)和主流的共同影響,結(jié)果在泵殼區(qū)域形成了低速區(qū).此外,根據(jù)觀察,在0.9Q工況下,導(dǎo)葉和泵殼內(nèi)的低速渦團(tuán)明顯多于其他2種工況,在導(dǎo)葉出口附近還存在1個(gè)大尺度回旋渦堵塞流道.在1.0Q與1.1Q工況下,流體從導(dǎo)葉流向泵殼時(shí)的擾動(dòng)隨著流動(dòng)方向逐漸減弱,這是由于在0.9Q工況下,流體的流速相對(duì)較低,流動(dòng)狀態(tài)較不穩(wěn)定,導(dǎo)致擾動(dòng)更容易傳播并形成低速渦團(tuán).而在1.0Q和1.1Q工況下,流體的流速較高,流動(dòng)狀態(tài)相對(duì)穩(wěn)定,擾動(dòng)的傳播受到一定的阻尼效應(yīng),因此,擾動(dòng)逐漸減弱.
2.3 泵殼內(nèi)速度渦團(tuán)分析
參考李正貴等[21]對(duì)水泵水輪機(jī)的渦結(jié)構(gòu)分析結(jié)果,提取的葉輪和導(dǎo)葉的三維渦結(jié)構(gòu)分布如圖9所示.
由圖9可知,每個(gè)過流部件上都存在著顯著的渦結(jié)構(gòu).在葉輪內(nèi)部,渦流現(xiàn)象主要集中在葉輪的前緣區(qū)域.對(duì)于導(dǎo)葉,渦流則主要分布在葉片的背面,尤其是靠近前緣的位置.當(dāng)工況達(dá)到1.1Q時(shí),泵殼與出水段的渦流結(jié)構(gòu)數(shù)量顯著增加,這導(dǎo)致出水口的流動(dòng)變得更加混亂.這是由于在高流量工況下,流體在泵殼內(nèi)形成了更多的渦簇,這些渦簇相互作用并引起渦系的擾動(dòng),導(dǎo)致出口處的流動(dòng)變得更加復(fù)雜和紊亂.而在1.0Q和0.9Q工況下,產(chǎn)生的大尺度渦團(tuán)逐漸減弱.
2.4 葉輪與導(dǎo)葉葉片壓力載荷分析
圖10為葉輪葉片的壓力載荷分布圖.圖中,S為流向位置.
研究過程中提取了不同展向的載荷分布,通常帶間隙的葉頂區(qū)域流動(dòng)更為復(fù)雜,包含葉頂泄漏渦、高速流動(dòng),葉片正反面壓差最為顯著,為了更好地反映葉片外側(cè)區(qū)域的壓力分布特性和載荷變化,選取了0.9倍展向.
通過觀察0.9倍展向長度的位置(span=0.9)可以發(fā)現(xiàn),在設(shè)計(jì)工況下,葉輪葉片的壓力面和吸力面的壓力變化呈現(xiàn)均勻分布,并無劇烈波動(dòng).在0.9倍展向長度處,1.0Q工況下的壓力差較其他工況有顯著增加.較大的壓力載荷差異表明,葉片能在更大程度上將輸入的機(jī)械能轉(zhuǎn)換為流體的動(dòng)能,從而提升了能量轉(zhuǎn)換的效率.較大的壓力載荷差值也表明,葉輪在引導(dǎo)流體流動(dòng)方面更為高效,并將動(dòng)能轉(zhuǎn)化為流體能量.這種增強(qiáng)的流體導(dǎo)向能力有助于降低流動(dòng)中的能量損耗和減少流動(dòng)分離的風(fēng)險(xiǎn),進(jìn)而提升了葉輪的整體性能.
圖11為不同流量下相同導(dǎo)葉葉片span=0.9下壓力載荷分布.
由圖11可以看到,在葉片前緣和葉片尾緣存在一個(gè)壓力驟降.葉片前緣的壓力驟降是因?yàn)閷?dǎo)葉入口受葉輪高速流動(dòng)沖擊,在前緣發(fā)生流動(dòng)分離;而發(fā)生于葉片尾緣處的壓力驟降,是因?yàn)樵谌~片工作面末端,葉片尾緣存在高速脫流,流體會(huì)逐漸從高速流動(dòng)轉(zhuǎn)變?yōu)榈退倭鲃?dòng).在這個(gè)過程中,流體會(huì)形成1個(gè)脫落渦,即流體離開葉片表面時(shí)形成的旋轉(zhuǎn)結(jié)構(gòu).脫落渦的形成會(huì)導(dǎo)致局部流體速度降低,從而引起壓力的下降.并且,在S接近1.0時(shí),3種工況下的葉片正反2個(gè)方向上的壓力負(fù)荷值均存在重疊現(xiàn)象;此外,從圖11還可以看出,在span=0.9處,導(dǎo)葉的載荷分布曲線相對(duì)平滑,但導(dǎo)葉背面壓力曲線波動(dòng)幅度較大,可能形成旋渦結(jié)構(gòu),這不利于流動(dòng)的引導(dǎo),可能導(dǎo)致較大的流動(dòng)分離現(xiàn)象.
3 軸流式核主泵水動(dòng)力性能試驗(yàn)
3.1 試驗(yàn)回路
試驗(yàn)回路的布置如圖12所示,試驗(yàn)標(biāo)準(zhǔn)參考國家標(biāo)準(zhǔn)GB/T 18149—2000[22-23].
3.2 軸流式核主泵外特性試驗(yàn)結(jié)果
通過在不同流量條件下對(duì)泵進(jìn)行性能測試,并將試驗(yàn)結(jié)果與模擬結(jié)果相對(duì)比,結(jié)果如圖13所示.
由圖13可知,在設(shè)計(jì)工況下,模擬得到的揚(yáng)程為11.19 m,而試驗(yàn)測得的揚(yáng)程為11.64 m,試驗(yàn)結(jié)果符合設(shè)計(jì)規(guī)范,且模擬值比試驗(yàn)值低3.87%,偏差在5%以內(nèi).同時(shí),模擬的效率為74.83%,而試驗(yàn)測得的效率為76.31%,試驗(yàn)結(jié)果同樣符合設(shè)計(jì)規(guī)范,模擬的效率較試驗(yàn)值低1.94%,偏差在3%以內(nèi).針對(duì)文中研究的核主泵模型,發(fā)現(xiàn)數(shù)值計(jì)算的效率比試驗(yàn)低,并且與傳統(tǒng)的泵數(shù)值計(jì)算和試驗(yàn)誤差規(guī)律不同.這種差異在后續(xù)該型號(hào)模型的開發(fā)中也存在.因此,泵數(shù)值計(jì)算和試驗(yàn)對(duì)比驗(yàn)證仍然是泵水力模型研發(fā)中必不可少的工作.本研究為后續(xù)水力模型的開發(fā)提供了參考依據(jù).同時(shí),泵內(nèi)部流動(dòng)的精確數(shù)值計(jì)算方法仍然是當(dāng)前業(yè)界面臨的普遍問題,需要進(jìn)一步深入研究.
4 結(jié) 論
1) 泵殼內(nèi)存在螺旋形擾動(dòng)和低速渦團(tuán),特別是在1.1Q流量工況下,渦簇相互作用導(dǎo)致出口處流動(dòng)更加復(fù)雜紊亂.導(dǎo)葉內(nèi)部存在明顯的不同尺度的渦結(jié)構(gòu),一方面會(huì)造成較大的能量耗散,另一方面會(huì)導(dǎo)致流道堵塞,影響過流的暢通性.為了減少這些影響,可以采取一些措施,如通過優(yōu)化泵殼和導(dǎo)葉的匹配、改善流動(dòng)控制、減小渦結(jié)構(gòu)的尺度和強(qiáng)度等方法改善流動(dòng)的穩(wěn)定性和均勻性.
2) 葉輪和導(dǎo)葉的渦結(jié)構(gòu)分布和壓力載荷分布表明,在設(shè)計(jì)工況下,葉輪葉片的工作面和背面所受的壓力分布較為平滑,且葉片工作面與背面之間的較大壓力差通常意味著葉輪的性能更優(yōu)越.導(dǎo)葉的載荷分布曲線相對(duì)平滑,但在背面壓力曲線波動(dòng)幅度較大,可能導(dǎo)致較大的流動(dòng)分離現(xiàn)象.后續(xù)可采取優(yōu)化導(dǎo)葉的幾何形狀、改善流動(dòng)控制等方法來減少流動(dòng)分離的影響.
3) 將軸流式核主泵的水動(dòng)力性能試驗(yàn)結(jié)果與數(shù)值模擬結(jié)果進(jìn)行了對(duì)比,數(shù)值模擬結(jié)果略低于試驗(yàn)結(jié)果.揚(yáng)程模擬值比試驗(yàn)值低3.87%,效率模擬值比試驗(yàn)值低1.94%.數(shù)值模擬結(jié)果低于試驗(yàn)結(jié)果可能是由于理論模型假設(shè)的不完全準(zhǔn)確、邊界條件的不確定性以及數(shù)值計(jì)算的精度和網(wǎng)格分辨率等因素的綜合影響.仍需開展試驗(yàn)驗(yàn)證和計(jì)算模型改進(jìn)從而提高數(shù)值計(jì)算方法的準(zhǔn)確性和可靠性.
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(責(zé)任編輯 盛杰)