【摘要】：當(dāng)混流式水輪機在偏離最優(yōu)工況,高于額定水頭下運行時,水流在轉(zhuǎn)輪葉片進(jìn)口靠近上冠處形成了部分脫流,產(chǎn)生葉道渦,并從葉片之間流出,影響水輪機的內(nèi)部流場,葉道渦發(fā)展到一定程度時就會引起水輪機的水力振動,當(dāng)振動超過允許值,尤其是長期處于振動狀態(tài),甚至與水輪機零部件產(chǎn)生共振時,會嚴(yán)重威脅到水電站機電設(shè)備的穩(wěn)定安全運行和工作人員的人身安全。 導(dǎo)水機構(gòu)作為混流式水輪機重要的過流部件。水流從蝸殼及固定導(dǎo)葉流出,通過繞流導(dǎo)葉,水流的流態(tài)發(fā)生改變,影響著轉(zhuǎn)輪進(jìn)口處水流速度的大小和方向。因此導(dǎo)葉翼型的形狀和安放位置對水輪機轉(zhuǎn)輪內(nèi)部流場有著重要的影響。 本文針對某混流式水輪機在高于額定水頭產(chǎn)生葉道渦并引起水力振動的情況,根據(jù)流體力學(xué)理論,分析水輪機產(chǎn)生葉道渦的原因。通過改變導(dǎo)葉的出流角和活動導(dǎo)葉形狀,從而改變水輪機內(nèi)部流場,以達(dá)到滿足轉(zhuǎn)輪進(jìn)口水流的要求。運用ANSYS CFX軟件,對研究的工況進(jìn)行流場的數(shù)值模擬,與電站的實測數(shù)據(jù)進(jìn)行對比,提出解決方案,達(dá)到減少振動的目的。
[Abstract]:When the Francis turbine deviates from the optimal operation condition and is higher than the rated water head, the water flow is partially separated from the inlet of the runner blade near the upper crown, resulting in the passage vortex, which flows out from the blades and affects the internal flow field of the turbine. When the blade vortex develops to a certain extent, it will cause the hydraulic vibration of the turbine. When the vibration exceeds the allowable value, especially if it is in a long-term state of vibration, and even resonates with the parts and components of the turbine, It will seriously threaten the stable and safe operation of electrical and mechanical equipment of hydropower station and the personal safety of staff. The guiding mechanism is an important overflow component of Francis turbine. The flow of water flows out of the volute and the fixed guide vane, and the flow pattern changes through the guide vane, which affects the size and direction of the flow velocity at the inlet of the runner. Therefore, the shape and placement position of the guide blade have an important influence on the internal flow field of the turbine runner. In this paper, according to the hydrodynamics theory, the cause of turbine vane vortex is analyzed according to the case that a Francis turbine produces blade vortex above the rated head and results in hydraulic vibration. By changing the outlet angle and the shape of the moving guide vane, the internal flow field of the turbine can be changed to meet the requirements of the inlet flow of the runner. By using ANSYS CFX software, the numerical simulation of the flow field under the studied condition is carried out, compared with the measured data of the power station, and the solution is put forward to reduce the vibration.
【學(xué)位授予單位】：西華大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TK733.1

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