Numerical evaluation of the clearance geometries effect on the flow field and performance of a hydrofoil
Numerical evaluation of the clearance geometries effect on the flow field and performance of a hydrofoil
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间隙几何形状对水翼流场和性能影响的数值评估
DOI：
10.1016/j.renene.2016.06.064
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发表时间：
2016-12-01
期刊：
影响因子：
8.7
通讯作者：
Wang, Zhengwei
中科院分区：
文献类型：
--
作者：
Guo, Qiang;Zhou, Lingjiu;Wang, Zhengwei
低水头潮汐发电机组的叶尖泄漏流具有效率损失和空化现象，是一个值得关注的问题。以NACA0009型水翼为例，研究了翼尖间隙形状和缝隙宽度对翼型流动特性和翼型性能的影响。对具有两个入射角(α=10度和5度)和不同归一化间隙宽度(Tau)的圆形尖翼和尖尖翼片进行了稳态非空化模拟。最小压力用来反映归一化涡旋强度(伽马*)和空化特性。不同流向位置的Gamma*-tau曲线表明，尖端翼片产生的漏涡相对较弱，曲线较为平坦，但其较大间隙处的尖端分离涡的Gamma*较高，增加了间隙空化的风险。缝隙内横截面上的流动特征表明，尖端减少了泄漏流动损失，并由于边界层分离而增加了速度梯度。尖尖箔的升力系数略高于圆形尖箔，在α=5度时差别不大，但在α=10度时偏差很大，尤其是在0.3度以内。
The blade tip leakage flow with efficiency losses and cavitation phenomena is a concern for the low-head tidal power units. A simplified case of NACA0009 hydrofoil in a water tunnel is used to investigate the effects of tip clearance geometries including the foil tip shape and gap width on the flow features and foil performance. Steady non-cavitating simulations are implemented for a round tip foil and a sharp tip foil with two incidence angles (alpha = 10 degrees and 5 degrees) and different normalized gap width (tau). The minimum pressure is used to reflect the normalized vortex intensity (Gamma*) and cavitation characteristics. The Gamma*-tau curves at different streamwise positions show that the sharp tip foil generates relatively weaker tip leakage vortex with more flat curves, but its higher Gamma* of tip separation vortex in wider gaps increases the risk of clearance cavitation. The flow features on a cross section inside the gap suggest that the sharp tip reduces the leakage flow losses and increases the velocity gradient due to the boundary layer separation. The lift coefficient is a little higher for the sharp tip foil than the round tip foil, with small differences for alpha = 5 degrees but noticeable deviations for alpha = 10 degrees especially within 0.3