可逆式水泵水輪機全流道三維非定常數(shù)值模擬
本文選題:水泵水輪機 + 水輪機工況 ; 參考:《昆明理工大學(xué)》2017年碩士論文
【摘要】:抽水蓄能電站水泵水輪機運行中,在水輪機或水泵正常運行、起動、停機、甩負荷等過程中,水壓、水流、轉(zhuǎn)速等會產(chǎn)生復(fù)雜的變化,并且引起水力振動、機械振動或者各部件的應(yīng)力變化。為了研究這些現(xiàn)象,采用CFD數(shù)值模擬的方法對某蓄能電站水泵水輪機幾何建模,采用RNG K-ε模型和SIMPLE算法對水泵水輪機三維全流道的額定流量Qr、0.19Qr、0.473Qr、0.655Qr、0.82Qr及1.2Qr工況以及水泵工況進行全流道三維非定常模擬,得到水泵水輪機內(nèi)部流場的數(shù)據(jù),經(jīng)過后處理軟件的處理來分析對比水泵水輪機內(nèi)部流場的分布以及變化情況。同時監(jiān)測蝸殼入口、活動導(dǎo)葉之間、導(dǎo)葉與轉(zhuǎn)輪之間無葉區(qū)以及尾水管直錐段和彎肘段壓力脈動情況,來分析水泵水輪機各個工況下各部分壓力脈動的時域分布以及頻域分布。結(jié)果表明:水泵水輪機蝸殼內(nèi)壓力呈現(xiàn)由外向內(nèi)靜壓力逐級遞減分布規(guī)律。隨之導(dǎo)葉開度增加出力增加,蝸殼的總體壓力降低;顒訉(dǎo)葉的進口頭部均有很強的靜壓力集中。在0.655Qr流量工況水泵水輪機蝸殼內(nèi)的周向流動及蝸殼斷面上的周向流動流態(tài)都非常紊亂有二次回流現(xiàn)象。在0.19Qr、0.473Qr等小流量工況下,在導(dǎo)葉出口形成射流使活動導(dǎo)葉與轉(zhuǎn)輪間無葉區(qū)流場惡劣及轉(zhuǎn)輪葉片進水邊附近形成渦結(jié)構(gòu),隨負荷增加,活動導(dǎo)葉開度增加,射流減弱,無葉區(qū)流場趨于平緩穩(wěn)定及葉片進水邊附近渦結(jié)構(gòu)消失。各個工況下轉(zhuǎn)輪結(jié)構(gòu)表面上,高壓紅色區(qū)域主要集中在轉(zhuǎn)輪葉片進水邊的頭部,轉(zhuǎn)輪下環(huán)進口邊及與葉片交接位置附近區(qū)域,隨著出力增加水輪機過流量加大,高壓區(qū)由葉片進水邊向葉片出水邊方向延伸。在偏離最優(yōu)工況較遠時,大的入口沖角將會使水流在轉(zhuǎn)輪葉片頭部出現(xiàn)脫流現(xiàn)象,形成渦結(jié)構(gòu)進入轉(zhuǎn)輪葉片間流動,形成葉道渦。在泵工況下,水流的流動方向與水輪機流動方向相反,由轉(zhuǎn)輪葉道甩出的水流直接撞擊活動導(dǎo)葉,給活動導(dǎo)葉帶來很大的沖擊,在導(dǎo)葉的流道中形成強烈的紊流擾動及渦結(jié)構(gòu),在蝸殼中的水流也特別的紊亂且都伴有二次回流的現(xiàn)象。尾水渦帶有多分支相互纏繞,導(dǎo)葉與轉(zhuǎn)輪無葉區(qū)受動靜干涉高頻脈動影響,尾水管區(qū)域受尾水渦帶低頻脈動影響,且各自向上下游傳播;各工況下導(dǎo)葉與轉(zhuǎn)輪間無葉區(qū)脈動頻率不變,各頻率幅值隨負荷增加而增加。
[Abstract]:In the operation of pump turbine in pumped storage power station, during the normal operation, starting, stopping and load rejection of the turbine or pump, the water pressure, water flow, speed and so on will produce complex changes, and will cause hydraulic vibration. Mechanical vibration or stress variation of components. In order to study these phenomena, the geometric model of pump turbine in a storage power station is modeled by CFD numerical simulation method. The RNG K- 蔚 model and SIMPLE algorithm are used to simulate the rated flow rate QR 0.19QrN 0.473Qrn0.655Qr0.82 Qr and the 1.2Qr working condition of the pump turbine, and the data of the internal flow field of the pump turbine are obtained by using the RNG K- 蔚 model and the SIMPLE algorithm. The distribution and variation of flow field in pump turbine are analyzed and contrasted by post-processing software. At the same time, the pressure pulsation of the inlet of the volute, the active guide vane, the vaneless zone between the guide vane and the runner, as well as the straight cone and elbow section of the draft tube are monitored to analyze the time-domain and frequency-domain distribution of the pressure pulsation in each working condition of the pump turbine. The results show that the internal pressure of the volute of water pump turbine decreases progressively from outside to inside. With the increase of the opening of the guide vane, the total pressure of the volute decreases. The inlet head of the movable guide vane has very strong static pressure concentration. The circumferential flow in the volute of the pump turbine and the circumferential flow on the section of the volute in the 0.655Qr flow condition are very disordered and have secondary reflux phenomenon. Under the condition of small flow rate of 0.19Qr-0.473Qr and so on, the formation of jet at the outlet of the guide vane makes the impeller flow field between the guide vane and the runner worse and the vortex structure formed near the inlet edge of the runner blade. With the increase of load, the opening of the active guide vane increases and the jet decreases. The flow field in the leafless region tends to be stable and the vortex structure near the inlet edge of the blade disappears. On the surface of the runner structure under various working conditions, the high pressure red area is mainly concentrated on the head of the inlet edge of the runner blade, the inlet edge of the lower ring of the runner and the area near the junction position between the runner and the blade. With the increase of the output force, the flow rate of the turbine increases. The high pressure zone extends from the inlet edge of the blade to the outlet edge of the blade. When deviating from the optimal condition, the large inlet angle of attack will cause the flow to deflow at the head of the runner blade, and the vortex structure will flow between the blades of the runner and form the vane vortex. Under the pump condition, the flow direction of the flow is opposite to that of the turbine. The flow from the runner impinges directly on the active guide vane, which brings great impact to the active guide vane, and forms a strong turbulent flow disturbance and vortex structure in the passage of the guide vane. The flow in the volute is also particularly disordered and accompanied by secondary reflux. The tailwater vortex is intertwined with multi-branches, the impeller and guide vane are affected by high frequency pulsation of static and static interference, and the region of draft tube is affected by the low-frequency pulsation of tailwater vortex zone, and propagates to the upstream and downstream respectively. The pulsation frequency of the vaneless region between the guide vane and the runner is constant, and the amplitude of each frequency increases with the increase of the load.
【學(xué)位授予單位】:昆明理工大學(xué)
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2017
【分類號】:TV743;TV734
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