| 黄彪*,王国玉,王复峰,高德明.非定常空化流场结构的实验研究[J].实验力学,2011,26(4):417~424 |
| 非定常空化流场结构的实验研究 |
| Experimental Investigation on Flow Field Structure of Unsteady Cavitation Flow |
| 投稿时间：2010-09-15 修订日期：2010-11-07 |
| DOI： |
| 中文关键词: 非定常空穴形态 高速摄像技术 粒子成像测速系统 |
| 英文关键词:unsteady cavitation high-speed video camera particle image velocimetry |
| 基金项目:国家自然科学基金(50979004)资助 |
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| 中文摘要: |
| 为深入研究非定常空化流场结构，本文用实验方法研究了绕Clark-Y型水翼的非定常空化流动现象。实验在空化水洞中进行，采用高速摄像技术观测了云状空化阶段的非定常空穴形态，并应用粒子成像测速系统(PIV)对绕水翼空化流场的速度场和涡量场等流动特性进行了同步的实验分析。研究表明：空化现象对流场结构有着重要的影响，在无空化和空化状态下，水翼前缘处的速度分布基本相同，但水翼中后部的流场结构存在较大的差异，在空化状态下，水翼中后部存在明显的水汽混相结构，该区域内的速度要低于主流区域，但涡量要大于其它区域，说明该区域存在明显的漩涡结构。在非定常云状空化的一个完整的发展周期中，空穴形态经历了初生-增长-溃灭的准周期过程，水汽混合相和汽相的分布决定了空化区域的形态结构与速度和涡量分布，在空穴的持续生长阶段，水翼中后部流场的低速高涡量区域的影响范围不断增大。在空穴周期型发展的后期，随着反向射流的发展，水翼中后部的流场结构处于强烈的非定常状态，水翼尾部的空化漩涡运动剧烈，空泡内部呈现出更为明显的漩涡结构，直至空泡完全脱落。 |
| 英文摘要: |
| Flow field structure of unsteady cavitation flow around a Clark-Y type hydrofoil was experimentally investigated. Experiments were carried out in a rectangular test section of a cavitation tunnel. A high-speed video camera was used to visualize the unsteady cloud cavitation flow pattern, and a particle image velocimetry (PIV) was also used to measure instantaneous velocity field and vortex field in cavitation flow field around the hydrofoil. Experimental results show that cavitation phenomennon has an important effect on flow field structure; whether or not cavitation, the velocity distribution is basically same around the leading edge of hydrofoil, but there is noticeable difference at the rear part of hydrofoil. In the unsteady cloud cavitation state, water and vapor mixture phase locates at the rear part, velocity in this region is lower than that of main flow area, but the vortex is larger than that in other regions, which indicats that obvious vortex structures exsits at the rear part. For cloud cavitation, a self-oscillatory periodic behavior of the whole sheet cavitation is obtained, with large length fluctuations and vapor cloud shedding. The distribution of vapor and vapor-water mixture phase determines the velocity and vortex distribution in cavitation area. When the attached cavity continues to grow, the region with lower velocity and high vortex at middle and rear parts of hydrofoil gradually expands. At the rear part of a cavitation development period, with the development of revease flow, the flow field structure around hydrofoil is strongly unstable, and more vortex structures can be seen in the cavitation area due to the frequently mass and momentum transformation. |
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