论文标题:基于N-S方程的混流式水轮机性能预估
Performance Pre-Evaluation of Francis Turbine Based on N-S Equation
论文作者 覃延春
论文导师 罗兴锜,论文学位 硕士,论文专业 水利水电工程
论文单位 西安理工大学,点击次数 81,论文页数 99页File Size9128k
2005-03-01论文网 http://www.lw23.com/lunwen_880269257/ N-S方程:计算流体动力学(CFD);非结构化网格;k-ε模型;性能预估;混流式水轮机
Navier-Stokes Equation; Computational Fluid Dynamic; Unstructured Grid; K-ε model; Performance pre-evaluation; Francis Turbine
本文在国家自然基金重点项目(90410019) 支持下完成。水轮机是水电站能量转换的主要部件,其性能直接影响到电站的效益,因此在转轮的设计阶段对转轮的性能进行预估就显得尤为重要。为克服模型试验周期长、投资人等缺点,本文基于N-S方程对水轮机流场进行计算并预估其性能。本文采用MDT进行水轮机三维实体造型,从而得到流场计算的三维几何模型。然后采用基于雷诺时均N-S方程与标准k-ε湍流模型来计算水轮机三维粘性湍流场,在非结构化网格中,采用基于有限元的有限体积法对方程进行离散,用压力校正法进行数值求解。基于水轮机三维流场计算预估流量,先假设一流量值,并根据流量值计算水轮机三维粘性湍流场并在此基础上计算水轮机的理论水头,将理论水头和试验水头进行比较,如果其差值满足给定要求则可以确定流量并预估该工况下的能量性能和空化性能,否则修正流量值反复迭代计算直到水头差值满足要求。本文结合实例,对模型混流式水轮机进行三维流场计算,预估了水轮机的流量、能量性能及空化性能,根据预估结果绘制了综合特性曲线图,将计算结果和试验数据进行了对比,说明本文所采用的方法进行混流式水轮机性能预估是可行的。
This thesis is supported by the National Natural Science Foundation Emphases Item of China (90410019). Hydraulic turbine is main component of energy conversion in PowerStation and whose performance directly affects PowerStation"s benefit, so it looks important to pre-evaluate performance during designing the turbine. In order to overcome the disadvantages of model experiment such as long period and great investment, this paper carries out the flow computation based on N-S equation and forecasts the performance.MDT is used to build hydraulic turbine"s three-dimensions solid and model of flow calculation can be realized. It adopts Reynolds time-average N-S equation and k-s turbulence model to calculate the inner 3-D viscid turbulence flow of hydraulic turbine. In the unstructured grid, the governing equations are discredited with Finite Volume Method based on Finite Element Method. And the pressure correction method is proposed in numerical calculations. Flux is pre-evaluated based on three-dimension viscous confused flow calculation. As the flux is unknown in advanced, we would suppose a flux value, three-dimension viscous confused flow of hydraulic turbine is calculated according to the supposed flux value and academic head will be calculated on basis of results. Put academic head into compare with experimental head. If difference meet the need, we can confirm the flux and pre-evaluate energy performance and cavitations performance, otherwise revise flux value and make iterative calculation until head differencemeet the need. According to aforesaid, the method mentioned in this paper has been realized. Through analysis of France turbine, flux, energy performances and cavitations performances are pre-evaluated. Hill chart is drawn based on pre-evaluated results. Compare is carried through between calculation result and experimental data, all the results show that the method used in this paper to pre-evaluate France turbine"s performance is feasible.
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