中文摘要：

采用DES湍流模型对791翼型在2°攻角及雷诺数为2.1×105的来流条件下,空化初生以及片状空化阶段三维非定常流动的结构进行了数值模拟,初步揭示了其流动特征。在空化初生阶段,空化初生的起始位置位于翼型最大厚度处,且展向外缘处的小空泡脱落呈周期性变化。片状空化空穴U型结构演变阶段,其空穴长度演变呈现出回缩-生长-回缩的明显特征。片状空化空泡脱落时,在指向翼型前缘发展的回射流和指向翼型展向中间截面的侧向射流相互耦合下,U型结构的两侧中部部分空泡开始脱离主体,向中间截面流动。U型结构两侧上的回射流是导致U型空穴回缩的主要原因。

英文摘要：

Based on detached eddy simulation（ DES） turbulent model,a numerical simulation has been applied on the study of three-dimensional unsteady cavitation flow around 791 hydrofoil at attack angle of 2° and with a Reynolds number ofRe= 2. 1 ×105,initially revealed its flow characteristics. In the primary stage of cavitation,the initial position of cavitation is located on the max thickness of the hydrofoil which is adhered to cavity with small volume and the small vacuoles off at the span-wise outer edge also periodically changes. In the stage of U-shaped structure sheet cavitation,it is clearly revealed that retraction-growth-retraction of the hole length. The coupling between the re-entrant jet flow which is developing towards the leading edge and the side jet flow which is developing towards the midsection,which results in the cavity shedding from the middle section of the U-shaped structure＇s the middle of the both sides and flowing towards the midsection. Besides,the re-entrant jet flow on the both sides of the Ushaped structure is also the major cause that leading to the cavity retraction.