本文選題：核主泵 + 空化流動(dòng)　； 參考：《蘭州理工大學(xué)》2017年碩士論文

【摘要】：在整個(gè)核電系統(tǒng)中,核主泵被喻為核島的“心臟”,是核反應(yīng)堆冷卻劑系統(tǒng)的動(dòng)力設(shè)備之一,也是一回路的主要壓力邊界。核電站中的一回路破口事故和熱阱喪失事故均可能導(dǎo)致核主泵發(fā)生空化,使其揚(yáng)程和效率降低,引起反應(yīng)堆芯過(guò)熱,空化嚴(yán)重時(shí)對(duì)核主泵性能和安全運(yùn)行造成嚴(yán)重影響。本文以一臺(tái)自主設(shè)計(jì)的核主泵模型泵為研究對(duì)象,通過(guò)數(shù)值計(jì)算,并結(jié)合相關(guān)試驗(yàn)數(shù)據(jù)深入研究了核主泵發(fā)生空化時(shí)其內(nèi)部空化流動(dòng)特性。主要研究?jī)?nèi)容與所得成果如下:1.核主泵空化流動(dòng)對(duì)能量轉(zhuǎn)換的影響。通過(guò)流線上壓力、速度等的變化規(guī)律,結(jié)合泵基本方程,對(duì)不同空化工況下核主泵葉輪內(nèi)動(dòng)、靜揚(yáng)程進(jìn)行深入研究。結(jié)果表明:核主泵內(nèi)流體的能量主要由葉輪中后段提供,且從前蓋板到后蓋板,流體獲得的能量逐漸減少�？栈蓴_葉輪內(nèi)液體的流動(dòng),導(dǎo)致空化區(qū)域相對(duì)速度增大,壓力減小,在氣泡密集區(qū)域,葉片對(duì)流體做功極少。同時(shí),隨著空化程度加劇,無(wú)空化區(qū)動(dòng)揚(yáng)程增大,靜揚(yáng)程減小,且靜揚(yáng)程減小幅度大于動(dòng)揚(yáng)程增大幅度,從而引起泵揚(yáng)程和效率下降。另外,在空化區(qū)域,隨著空化程度加劇,動(dòng)、靜揚(yáng)程突變程度加劇,增大了葉輪內(nèi)的流動(dòng)損失,進(jìn)而導(dǎo)致泵揚(yáng)程及效率進(jìn)一步下降。2.空化發(fā)展對(duì)核主泵性能的影響。選擇4種空化工況,通過(guò)對(duì)比得出核主泵在發(fā)生空化時(shí),其性能及內(nèi)部流場(chǎng)變化規(guī)律。結(jié)果表明:核主泵發(fā)生空化時(shí),其揚(yáng)程、效率和功率變化對(duì)有效空化余量降低的敏感程度不同。隨著空化程度加劇,揚(yáng)程變化率最大,效率次之,功率變化率最小。同時(shí),由空化產(chǎn)生的氣泡改變了空化區(qū)域流體狀態(tài),使流體動(dòng)力粘度減小,導(dǎo)致空化區(qū)域湍流耗散率減小,降低了湍流耗散損失。3.葉片進(jìn)口邊幾何形狀對(duì)核主泵空化流動(dòng)特性的影響。對(duì)4種不同葉片進(jìn)口邊幾何形狀的模型泵進(jìn)行空化模擬,得出葉片進(jìn)口邊幾何形狀對(duì)核主泵性能的影響規(guī)律。結(jié)果表明:葉片進(jìn)口邊減薄,使葉片進(jìn)口對(duì)流體的排擠作用減弱,改善了葉片對(duì)進(jìn)口流動(dòng)條件改變的適應(yīng)性,減小葉片進(jìn)口處的流動(dòng)損失,使效率升高。另外,增大葉片進(jìn)口邊圓角,進(jìn)口減薄程度加劇,使進(jìn)口處過(guò)流斷面面積增大,流速降低,進(jìn)而導(dǎo)致壓力增大,且低壓區(qū)逐漸向葉片出口移動(dòng),在發(fā)生空化時(shí),氣泡對(duì)葉片進(jìn)口處流體流動(dòng)影響逐漸變小。同時(shí),隨著葉片進(jìn)口減薄程度加劇,葉片進(jìn)口更加接近流線型,液體繞流葉片頭部時(shí)產(chǎn)生沖擊減小,使葉片吸力面靠近進(jìn)口處的最低壓力有所增大。
[Abstract]:In the whole nuclear power system, the nuclear main pump is described as the "heart" of the nuclear island, is one of the power equipment of the nuclear reactor coolant system, and is also the main pressure boundary of the primary circuit.The primary circuit break accident and heat trap loss accident in the nuclear power plant may lead to cavitation of the nuclear main pump, reduce its head and efficiency, cause the reactor core to overheat, and seriously affect the performance and safe operation of the nuclear main pump when the cavitation is serious.In this paper, a self-designed nuclear pump model pump is taken as the research object. The internal cavitation flow characteristics of the nuclear main pump during cavitation are studied by numerical calculation and combined with relevant experimental data.The main contents and results are as follows: 1.The effect of cavitation flow on energy conversion in nuclear main pump.Through the variation of the pressure and velocity in the streamline, combined with the basic equations of the pump, the dynamic and static head of the impeller of the nuclear main pump under different cavitation conditions is studied in depth.The results show that the energy of the fluid in the nuclear main pump is mainly supplied by the middle and back section of the impeller, and the energy obtained by the fluid decreases gradually from the front cover plate to the back cover plate.Cavitation interferes with the flow of liquid in the impeller, resulting in the increase of the relative velocity and the decrease of the pressure in the cavitation region. In the dense bubble area, the blade does little work on the fluid.At the same time, with the increase of cavitation degree, the dynamic head increases and the static head decreases in the no-cavitation area, and the amplitude of the static head is larger than that of the moving head, which leads to the decrease of pump head and efficiency.In addition, in the cavitation area, with the increase of cavitation degree, the sudden change degree of static head and cavitation increase, which increases the flow loss in the impeller, which leads to the further decrease of pump head and efficiency.The effect of cavitation development on the performance of nuclear main pump.Four cavitation conditions were selected and the performance and internal flow field of the nuclear main pump during cavitation were obtained by comparison.The results show that when cavitation occurs in the nuclear main pump, the sensitivity of the head, efficiency and power changes to the reduction of the effective cavitation margin is different.With the increase of cavitation degree, the lift change rate is the largest, the efficiency is the second, and the power change rate is the least.At the same time, the bubble produced by cavitation changes the fluid state in the cavitation region, reduces the dynamic viscosity of the fluid, reduces the turbulent dissipation rate and reduces the turbulent dissipation loss of the cavitation region.Effect of blade inlet geometry on cavitation flow characteristics of nuclear main pump.The cavitation simulation of four kinds of model pumps with different geometry of inlet edge of blade was carried out, and the influence of geometry of inlet edge of blade on the performance of core main pump was obtained.The results show that the thinning of the inlet edge of the blade weakens the extrusion effect of the blade inlet to the fluid, improves the adaptability of the blade to the change of the inlet flow conditions, reduces the flow loss at the inlet of the blade, and increases the efficiency.In addition, increasing the angle of the inlet edge of the blade, increasing the degree of the inlet thinning, increasing the cross section area at the inlet, decreasing the velocity of flow, causing the pressure to increase, and moving gradually to the blade outlet in the low pressure region, when cavitation occurs,The effect of bubble on the fluid flow at the inlet of the blade is gradually reduced.At the same time, with the increase of blade inlet thinning, the blade inlet is closer to the streamline type, and the impact of liquid around the blade head decreases, which increases the minimum pressure near the inlet of the blade suction surface.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM623.4

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本文編號(hào)：1751984