To study the hydrodynamic performance characteristics of tandem turbines, put forward the reasonable layout scheme and increase power generation efficiency of tidal power station, the transient numerical simulations are performed to investigate a three-blade vertical axis tidal turbine, and the upstream turbine's hydrodynamic performance and the wake effect on the downstream turbine are analyzed. Considering that the turbine's blade has the same profile on the span, the turbine model is simplified to 2D model and the open source fluid mechanics software OpenFOAM is used to simulate the flow field. Firstly,changing law of turbine's power coefficient with tip speed ratio is obtained through the simulation of a single turbine. By comparing with the experimental data in reference,it is verified that the OpenFOAM numerical model can predict the hydrodynamic performance of the 2D vertical axis turbine accurately under the reasonable setting by using the k-ω SST turbulence model and the PIMPLE algorithm. Then two tandem turbines cases are simulated,the distance between two turbines is from 5D to 50D,where D stands for turbine's diameter. The wake characteristics of the sections behind turbines and the influence characteristics of turbines' distance on the downstream turbine's hydrodynamic performance are obtained. Finally the results show that when the distance between two tandem turbines is more than 40D, the effect of upstream turbine on the downstream turbine could be ignored.%为研究串列水轮机组水动力性能并提出合理的水轮机布置方案,提高潮流能电站的发电效率,针对三叶片竖轴水轮机进行瞬态数值模拟,分析了串列布置水轮机组上游水轮机的水动力性能及尾流场对下游水轮机水动力性能的影响.考虑到竖轴水轮机叶片展向剖面相同的特点,将模型简化为二维模型并利用开源流体力学软件OpenFOAM对水轮机进行了数值分析.首先通过模拟单个水轮机的运行,得出了能量利用率随叶尖速比的变化规律,并通过与文献中实验数据的对比验证了OpenFOAM数值模型在合理的设置下,采用k-ω SST湍流模型和PIMPLE算法,可以准确计算二维竖轴水轮机的水动力性能.之后模拟了两个串列放置的水轮机,水轮机之间的距离范围取5~50倍水轮机直径,分析得出了竖轴水轮机后方各剖面的尾流特性,以及水轮机间距对下游水轮机水动力性能的影响特性.分析结果表明,两个串列水轮机的间距大于40倍水轮机直径时,上游水轮机尾流场对下游水轮机性能的影响可以忽略.
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