本文選題：混流式水輪機(jī) + 增容改造��； 參考：《蘭州理工大學(xué)》2017年碩士論文

【摘要】：對(duì)已建具有增容潛力的水電站機(jī)組更新改造,成本小、收效快,社會(huì)經(jīng)濟(jì)效益可觀。運(yùn)行多年的部分中小型電站普遍存在著技術(shù)指標(biāo)落后、制造質(zhì)量差、過(guò)流部件磨損嚴(yán)重、設(shè)備年久失修、發(fā)電量逐年減少等問(wèn)題,不僅浪費(fèi)大量的水力資源,而且影響著電站的安全運(yùn)行。目前CFD技術(shù)發(fā)展迅速,成果顯著,達(dá)到了工程應(yīng)用水平。探究如何應(yīng)用CFD這一先進(jìn)工具對(duì)老舊電站的水輪機(jī)進(jìn)行增容改造具有重大現(xiàn)實(shí)意義。本文針對(duì)青海古浪堤水電站HL741-WJ-84水輪機(jī)在實(shí)際運(yùn)行中出現(xiàn)的問(wèn)題,“量體裁衣”式制定增容改造方案。首先對(duì)比分析諸多較優(yōu)模型轉(zhuǎn)輪,初步選取目標(biāo)轉(zhuǎn)輪;然后根據(jù)水輪機(jī)既定通流部件的幾何約束條件對(duì)所選目標(biāo)轉(zhuǎn)輪進(jìn)行一定改型,使轉(zhuǎn)輪既保持本身優(yōu)良性能又滿足電站改造要求。鑒于小型臥式水輪機(jī)在汛期運(yùn)行時(shí)出現(xiàn)轉(zhuǎn)輪被雜物頻繁堵塞而影響正常發(fā)電的情形,從增加水輪機(jī)出力與過(guò)流能力的角度出發(fā),采用在改型轉(zhuǎn)輪基礎(chǔ)上減少三個(gè)葉片后制造新轉(zhuǎn)輪的方案對(duì)原水輪機(jī)增容改造。以CFD為基礎(chǔ)探究可用于水輪機(jī)實(shí)際改造的數(shù)值計(jì)算及水力性能估測(cè)方法,對(duì)改造結(jié)果進(jìn)行數(shù)值驗(yàn)證并分析水流流態(tài)是否均勻合理以達(dá)到定性指導(dǎo)和評(píng)價(jià)改造方案的目的。本文基于流場(chǎng)數(shù)值計(jì)算,分析水輪機(jī)增容改造前后的流場(chǎng),預(yù)估機(jī)組的整體性能。通過(guò)求解Reynolds時(shí)均N-S方程,在FLUENT中選取標(biāo)準(zhǔn)κ-ε湍流模型并采用SIMPLE算法,對(duì)改造前后的水輪機(jī)全流道進(jìn)行流場(chǎng)計(jì)算,模擬改造前后的水輪機(jī)在四個(gè)典型工況下運(yùn)行時(shí)的流動(dòng)狀況,求得各個(gè)工況下水輪機(jī)整體及各通流部件內(nèi)的流動(dòng)信息,獲得改造前后水輪機(jī)水動(dòng)力學(xué)的特性差異,給出了水輪機(jī)更換轉(zhuǎn)輪改造后效率和出力隨導(dǎo)葉開(kāi)度變化的規(guī)律。改造后水輪機(jī)整體流動(dòng)均勻、流態(tài)分布合理,幾乎不存在流場(chǎng)的擾動(dòng)。蝸殼中水流流動(dòng)平穩(wěn)順暢,過(guò)流能力增強(qiáng),不存在壓力與速度突變等不穩(wěn)定現(xiàn)象;葉片的數(shù)值計(jì)算結(jié)果表明,減少葉片數(shù)對(duì)葉片背面壓力分布影響較大,轉(zhuǎn)輪在各工況下運(yùn)行時(shí)因葉片背面負(fù)壓產(chǎn)生的翼型空蝕較原HL741轉(zhuǎn)輪有所改善,但葉片背面靠近下環(huán)處進(jìn)口段極小區(qū)域存在空蝕性能惡化的現(xiàn)象,為安全起見(jiàn)可對(duì)該區(qū)域采取一定的抗空蝕措施;尾水管在原最優(yōu)工況與較大開(kāi)度之間的流動(dòng)狀況均勻穩(wěn)定,偏心渦帶減弱,整體流線順暢,流動(dòng)性能、水力性能等要優(yōu)于改造前;改造后水輪機(jī)最優(yōu)工況點(diǎn)偏向大流量區(qū),機(jī)組增容幅度可達(dá)13%,效率達(dá)到91%。本文所得結(jié)果可用于HL741-WJ-84水輪機(jī)的實(shí)際改造并指導(dǎo)電站的運(yùn)行。
[Abstract]:The cost is small, the effect is fast and the social economic benefit is considerable. Some small and medium-sized power stations which have been running for many years have some problems, such as backward technical indexes, poor manufacturing quality, serious wear and tear of overcurrent parts, old equipment disrepair and decreasing power generation year by year, which not only waste a large number of hydraulic resources, but also reduce the power generation year by year. It also affects the safe operation of the power station. At present, the CFD technology develops rapidly, the achievement is remarkable, has reached the engineering application level. It is of great practical significance to explore how to apply CFD, an advanced tool, to the retrofit of hydraulic turbines in old power stations. Aiming at the problems of HL741-WJ-84 turbine in practical operation of Gulangdi Hydropower Station in Qinghai Province, this paper formulates the scheme of capacity increase and retrofit. Firstly, many better model runner are compared and analyzed, then the target runner is selected preliminarily, and then the selected target runner is modified according to the geometry constraint condition of the given flow passage part of the turbine. The runner can not only maintain its own excellent performance but also meet the requirements of power plant transformation. In view of the fact that the runner of a small horizontal turbine is clogged frequently by sundries during flood season, which affects the normal power generation, this paper starts from the point of view of increasing the outputting force and overcurrent capacity of the turbine. The new runner after reducing three blades on the basis of the modified runner is adopted to increase the capacity of the original turbine. Based on CFD, this paper explores the numerical calculation and hydraulic performance estimation method which can be used in the actual retrofit of hydraulic turbines, and verifies the results of the revamping and analyzes whether the water flow pattern is even and reasonable in order to achieve the purpose of qualitatively guiding and evaluating the retrofit scheme. Based on the numerical calculation of the flow field, the flow field before and after the retrofitting of the turbine is analyzed, and the overall performance of the turbine is predicted. By solving the average N-S equation of Reynolds, selecting the standard 魏-蔚 turbulence model in FLUENT and using the SIMPLE algorithm, the flow field of the turbine before and after the revamping is calculated, and the flow state of the turbine before and after the revamping is simulated under four typical operating conditions. The flow information of the whole turbine and the flow passage parts are obtained, and the differences of hydrodynamic characteristics of the turbine before and after the revamping are obtained. The law of the change of the efficiency and the output force with the guide vane opening after the revamping of the turbine runner is given. After the revamping, the whole flow of the turbine is uniform, the flow distribution is reasonable, and there is almost no disturbance of the flow field. In volute case, the flow of water is smooth and smooth, the capacity of overcurrent is enhanced, and there is no unstable phenomenon such as sudden change of pressure and velocity, and the numerical calculation results of blade show that reducing the number of blades has a great influence on the distribution of pressure on the back of blade. The cavitation erosion of the airfoil caused by the negative pressure on the back of the blade is better than that of the original HL741 runner when the runner is running under various operating conditions, but the cavitation erosion performance is deteriorated in the very small area near the inlet of the lower ring on the back of the blade. For the sake of safety, some anti-cavitation measures can be taken in this area; the flow condition of draft tube is uniform and stable between the original optimum working condition and the larger opening, the eccentric vortex belt is weakened, the whole flow line is smooth, and the fluidity is very good. The hydraulic performance of the turbine is better than that of before the retrofit, the optimum operating point of the turbine deviates to the large flow zone after the revamping, the capacity increase range of the unit can reach 13%, and the efficiency reaches 91%. The results obtained in this paper can be applied to the practical transformation of HL741-WJ-84 turbines and guide the operation of power stations.
【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)】：TV738

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本文編號(hào)：1947643