超流氦中喷射流流场的PIV可视化观察  

Observation of jet flow into superfluid helium using particle image velocimetry technique

作　　者：金滔[1] FUZIER Sylvie VAN SCIVER Steven 

机构地区：[1]浙江大学制冷与低温研究所,浙江杭州310027 [2]美国国家高磁场实验室,美国佛罗里达32310

出　　处：《浙江大学学报（工学版）》2010年第3期473-475,562,共4页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(50776075)

摘　　要：利用粒子成像测速仪(PIV)对射入到超流氦液浴中的喷射流的初始发展阶段进行观察,主要考察了流型和流场分布状况,旨在分析通过喷射流来实现的示踪粒子投放过程的实际效果及其对测量精度的影响情况.超流氦液浴温度为1.8K,示踪粒子为1.7μm直径的复合物粒子,高速相机拍摄的相邻照片间隔时间为3ms.实验中观察到的喷射流具有一抛物线形状的流型,与正常流体中观察到的喷射流具有一定的相似性.速度场分析结果也显示,射流内的速度场分布远不如正常流体中均匀和规律变化,其中存在许多局部的涡旋流.沿着射流方向上速度的波动幅度越来越小,平均速度在行进了约35mm后降至2mm/s量级.The initial development of the jet flow into superfluid helium （He II） bath was observed by particle image velocimetry （PIV）,focusing on the flow structure and velocity field inside the jet flow,which could be the basis for the analysis of seeding process with a jet of particle-carrying fluid into He II,since it has decisive influence on the measurement accuracy. The He II bath had a temperature of 1.8 K,the polymer seeding particles had the diameter of 1.7μm,and the time span between two CCD pictures was 3 ms. The observed jet flow in He II had a parabolic flow pattern,similar to that in the normal fluid,however,the velocity field of jet flow was less uniform and regular than the normal fluid and much vortex flow was also found in some local areas. The amplitude of the oscillating velocity decreased along the progressive direction of jet flow and the mean velocity reached at about 2 mm/s after the flow left the nozzle for a distance of 35 mm.

关 键 词：粒子成像测速仪(PIV) 超流氦(氦II) 喷射流 涡旋流 

分 类 号：O512.1[理学—低温物理]