【摘要】：尾水管在水輪機(jī)的運(yùn)行中起著回收能量提高效率的作用,在非最優(yōu)工況下運(yùn)行時,轉(zhuǎn)輪出口水流有一定的旋轉(zhuǎn)渦量,有時會產(chǎn)生尾水渦帶,引起尾水管的振動,降低機(jī)組的運(yùn)行穩(wěn)定性。改變尾水管中水流的流動狀態(tài)可以減輕振動、提高效率。尾水管的截面變化應(yīng)符合一定的規(guī)律,盡量避免橫截面積的劇烈增加或減小,這樣才能使水流的壓力、流速等均勻變化。本文以老撾某水電站的HLA858a-LJ-182型號水輪機(jī)為研究對象,以減小尾水管中的能量損失、提高機(jī)組效率為目的,通過調(diào)整尾水管的截面面積變化,使各個截面之間的面積變化曲線過渡更加平滑自然,從而來改變各個截面之間水流的速度,并運(yùn)用數(shù)值模擬計算軟件對優(yōu)化修型前后的尾水管在額定流量工況、最優(yōu)工況、大流量工況和小流量工況四種工況下進(jìn)行定常模擬對比分析,最后還在最易產(chǎn)生渦帶的小流量工況下進(jìn)行非定常模擬分析,通過壓力和速度云圖及一些數(shù)值曲線來分析優(yōu)化結(jié)果的作用。計算分析結(jié)果表明:本文采用的優(yōu)化方法,在額定工況和最優(yōu)工況下,尾水管整體性能有一定的提升;大流量工況下,水力性能有所下降;小流量工況下,整體流態(tài)變化不大。但是在常出現(xiàn)渦帶的小流量工況下,優(yōu)化后的尾水管對減小渦帶振動有一定的作用。
[Abstract]:The draft tube plays a role of recovering energy and improving efficiency in the operation of the turbine. When running under non-optimal conditions, the runner outlet flow has a certain amount of rotational vorticity, sometimes the tailwater vortex belt will be produced, which will cause the vibration of the draft tube. Reduce the operating stability of the unit. Changing the flow state of the draft tube can reduce the vibration and improve the efficiency. The variation of the section of the draft tube should conform to certain rules and avoid the sharp increase or decrease of the cross section area so as to make the pressure and velocity of the flow change uniformly. In order to reduce the energy loss in the draft tube and improve the efficiency of the unit, this paper takes the HLA858a-LJ-182 type hydraulic turbine of a hydropower station in Laos as the research object, and adjusts the variation of the cross-section area of the draft tube. Make the transition of area change curve between each section more smooth and natural, so as to change the velocity of water flow between each section, and use the numerical simulation calculation software to optimize the draft tube before and after the modification at rated flow condition, the optimal working condition, At last, the unsteady simulation analysis is carried out under the condition of high flow rate and small flow rate, and the unsteady simulation analysis is carried out under the condition of small flow which is the easiest to produce vortex band. The effect of optimization results is analyzed by using pressure and velocity cloud maps and some numerical curves. The results of calculation and analysis show that the overall performance of the draft tube is improved under the rated and optimal conditions, the hydraulic performance of the draft tube is decreased under the condition of large flow rate, and that of the whole flow pattern is not changed under the condition of small flow rate. However, under the condition of small flow rate of vortex band, the optimized draft tube plays a certain role in reducing the vortex band vibration.
【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】：TK730.1

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本文編號：2152687