中文摘要：

海流机是海流能利用的一种新形式,其空化性能的好坏直接影响到海流发电机组的安全和稳定运行。基于两相混合流模型对一模型水平轴海流机空化流动进行研究,得到不同空化数下的空泡形态及其性能曲线。数值模拟结果表明,采用数值计算方法能够有效地预测海流机的空化现象,计算得到模型海流机的初生空化数,空泡形态与试验结果相类似;海流机空化通常发生在近叶尖吸力面上,并随空化数的降低沿叶片展向和弦向变长;空化数相对较高时,空化出现在叶片弦向中间区域,随空化数降低向叶片尾缘发展;空化初生时,海流机性能没有明显改变;只有当空化数降低到一定程度时,海流机推力升高,输出功率下降,海流机性能恶化,实际运行中应当避免在此工况下运行。

英文摘要：

Marine current turbine（MCT） is a new mechanical device for marine current energy utilization,and cavitation performance of it is important for the safe and stable operation.Based on two phase homogeneous mixture model,numerical simulation of the cavitating flow is performed on a horizontal axis marine current turbine（HMCT）.Cavity shapes and performance of the HMCT in variable cavitation numbers are obtained.Numerical results show that the numerical method can be used to predict the cavitation performance of marine current turbine;the incipient cavitation number is predicted,and the cavity shape is similar with the experiment;cavitation usually appears in the suction surface of the blade and locates in the area near the blade tip,and becomes longer in the span and chord direction with lower cavitation number;when the cavitation number is relatively higher,cavitating region locates in the middle area of the blade in chord direction,and develops to the trailing edge of the blade when cavitation number becomes lower;when the cavitation number equals to the incipient cavitation number,performance of the HMCT has no change almost,only when cavitation number reduces to some extent,the output power decreases and thrust increase,which means the marine current turbine operates in a bad condition and this condition should be avoided in the practical operation.