水轮机尾水管内部流场分析及优化设计
发布时间：2018-07-29 12:33
【摘要】：尾水管在水轮机的运行中起着回收能量提高效率的作用,在非最优工况下运行时,转轮出口水流有一定的旋转涡量,有时会产生尾水涡带,引起尾水管的振动,降低机组的运行稳定性。改变尾水管中水流的流动状态可以减轻振动、提高效率。尾水管的截面变化应符合一定的规律,尽量避免横截面积的剧烈增加或减小,这样才能使水流的压力、流速等均匀变化。本文以老挝某水电站的HLA858a-LJ-182型号水轮机为研究对象,以减小尾水管中的能量损失、提高机组效率为目的,通过调整尾水管的截面面积变化,使各个截面之间的面积变化曲线过渡更加平滑自然,从而来改变各个截面之间水流的速度,并运用数值模拟计算软件对优化修型前后的尾水管在额定流量工况、最优工况、大流量工况和小流量工况四种工况下进行定常模拟对比分析,最后还在最易产生涡带的小流量工况下进行非定常模拟分析,通过压力和速度云图及一些数值曲线来分析优化结果的作用。计算分析结果表明:本文采用的优化方法,在额定工况和最优工况下,尾水管整体性能有一定的提升;大流量工况下,水力性能有所下降;小流量工况下,整体流态变化不大。但是在常出现涡带的小流量工况下,优化后的尾水管对减小涡带振动有一定的作用。
[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.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TK730.1
[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.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TK730.1
【参考文献】
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