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

【摘要】：對已建具有增容潛力的水電站機組更新改造,成本小、收效快,社會經(jīng)濟效益可觀。運行多年的部分中小型電站普遍存在著技術(shù)指標落后、制造質(zhì)量差、過流部件磨損嚴重、設(shè)備年久失修、發(fā)電量逐年減少等問題,不僅浪費大量的水力資源,而且影響著電站的安全運行。目前CFD技術(shù)發(fā)展迅速,成果顯著,達到了工程應(yīng)用水平。探究如何應(yīng)用CFD這一先進工具對老舊電站的水輪機進行增容改造具有重大現(xiàn)實意義。本文針對青海古浪堤水電站HL741-WJ-84水輪機在實際運行中出現(xiàn)的問題,“量體裁衣”式制定增容改造方案。首先對比分析諸多較優(yōu)模型轉(zhuǎn)輪,初步選取目標轉(zhuǎn)輪;然后根據(jù)水輪機既定通流部件的幾何約束條件對所選目標轉(zhuǎn)輪進行一定改型,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在汛期運行時出現(xiàn)轉(zhuǎn)輪被雜物頻繁堵塞而影響正常發(fā)電的情形,從增加水輪機出力與過流能力的角度出發(fā),采用在改型轉(zhuǎn)輪基礎(chǔ)上減少三個葉片后制造新轉(zhuǎn)輪的方案對原水輪機增容改造。以CFD為基礎(chǔ)探究可用于水輪機實際改造的數(shù)值計算及水力性能估測方法,對改造結(jié)果進行數(shù)值驗證并分析水流流態(tài)是否均勻合理以達到定性指導(dǎo)和評價改造方案的目的。本文基于流場數(shù)值計算,分析水輪機增容改造前后的流場,預(yù)估機組的整體性能。通過求解Reynolds時均N-S方程,在FLUENT中選取標準κ-ε湍流模型并采用SIMPLE算法,對改造前后的水輪機全流道進行流場計算,模擬改造前后的水輪機在四個典型工況下運行時的流動狀況,求得各個工況下水輪機整體及各通流部件內(nèi)的流動信息,獲得改造前后水輪機水動力學(xué)的特性差異,給出了水輪機更換轉(zhuǎn)輪改造后效率和出力隨導(dǎo)葉開度變化的規(guī)律。改造后水輪機整體流動均勻、流態(tài)分布合理,幾乎不存在流場的擾動。蝸殼中水流流動平穩(wěn)順暢,過流能力增強,不存在壓力與速度突變等不穩(wěn)定現(xiàn)象;葉片的數(shù)值計算結(jié)果表明,減少葉片數(shù)對葉片背面壓力分布影響較大,轉(zhuǎn)輪在各工況下運行時因葉片背面負壓產(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)處進口段極小區(qū)域存在空蝕性能惡化的現(xiàn)象,為安全起見可對該區(qū)域采取一定的抗空蝕措施;尾水管在原最優(yōu)工況與較大開度之間的流動狀況均勻穩(wěn)定,偏心渦帶減弱,整體流線順暢,流動性能、水力性能等要優(yōu)于改造前;改造后水輪機最優(yōu)工況點偏向大流量區(qū),機組增容幅度可達13%,效率達到91%。本文所得結(jié)果可用于HL741-WJ-84水輪機的實際改造并指導(dǎo)電站的運行。
[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)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV738

【參考文獻】

相關(guān)期刊論文 前10條

1 王繼娥;鄒磊;代繼江;耿清華;;銅街子水電站水輪機增容改造的優(yōu)化設(shè)計[J];人民長江;2016年01期

2 ;2015世界水電大會專家觀點集萃[J];中國水利;2015年10期

3 曹玉良;王永生;靳栓寶;;噴水推進軸流泵三元水力設(shè)計[J];交通運輸工程學(xué)報;2015年02期

4 王釗寧;羅興，

本文編號：1947643