Vertical-axis tidal turbine as one kind of energy conversion systems was extensively tested and studied. Sliding mesh model,multiphase flow model and user-defined function of CFD was utilized, through the solution of moment equation,continuity equation and bubble transport equation under the entire wet flow of cavitation ignored and cavitating flow of cavitation considered were simulated respectively. The results showed that great differences of the flow field near the turbine upstream surface. Cavitation not only caused the bubbles around the turbine blades,but also disturbed the flow field around the turbine blades. Cavitation reduced the force on the principal axis and power efficiency Cp The peak of power efficiency was 0.23 when the tip speed ratio λ=2.75 ,and decreased by 25% compared with the wet flow.%竖轴潮流水轮机是目前被广泛研究的潮流能的转换装置.利用CFD软件FLUENT的滑移网格模型、多相流模型和用户自定义函数UDF,通过求解动量方程、连续性方程以及气泡输运方程,分别在忽略空化的全湿流和考虑空化的空化流情况下对竖轴潮流水轮机进行了非定常数值模拟.结果表明,两种数值模型下的水轮机附近的流场在水轮机的上游面差别很大,空化不仅使水轮机叶片周围产生气泡,而且严重扰乱了水轮机叶片周围的流场,从而导致水轮机水动力性能的改变.空化的存在使潮流水轮机叶片对主轴的作用力减小,使水轮机的能量利用率Cp降低,当尖速比λ=2.75时,Cp值最大,为0.23,比忽略空化时降低了25％.
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