绕水翼超空化流动形态与速度分布

为揭示超空化流场结构特性，利用高速全流场显示技术，观察了绕hydronautics水翼的超空 化流动形态，并利用数字粒子图像测速仪(DPIV)测量了其速度分布. 在测量空穴内部流速 分布时，采用空化流场中的空化泡作为示踪粒子来显示流动结构. 结果表明：随着空化数 的降低，超空化流动显现出了明显的阶段特征，其中水汽混合相和汽相的分布决定了空化区 域的形态与流速分布；空化区和主流区的汽液交界面处存在着较大的速度梯度；低速分布区 域随着空化数的降低由水翼吸力面中后部向水翼下游移动；在空化区域内部，水汽混合区的 速度相对较低，而汽相区则与主流区有着相近的速度分布. 关键词超空化水翼、DPIV、高速摄像、空化形态、流速分布

CHARACTERISTICS OF SUPERCAVITATING FLOWS AROUND A HYDROFOIL

Supercavitation around a hydrofoil is studied experimentally to address the flowing characteristics. A high-speed video camera is used to visualize the flow structures under different cavitation numbers. The digital particle image velocimetry (DPIV) is employed to measure the velocity fields. The bubbles among the cavitating fields are used as the tracer particles to survey the velocity distribution inside the cavity and improve the tracking capability of the tracer particles. The results show that three distinct supercavitating flow regimes can be observed with the decreasing cavitation numbers, in which the cavitation structure varies with the distribution of the water-vapor mixing phase and vapor phase. A large velocity gradient exists around the interface between the cavitation area and the free stream. In the cavitation area, the lower-velocity region moves from the foil's middle part to the downstream with the decrease of the cavitation number. The fluid velocity is low in the water-vapor mixture region, while with the similar distribution in the free stream and the vapor region.