摘要
为了掌握轴流泵叶顶泄漏涡(TLV)的形成演化机理,评估涡形成空化条件和间隙宽度的影响,进行了轴流泵间隙泄漏流动实验和数值计算分析。通过流线涡量云图三维可视化分析,得到间隙流动特征及其涡结构,并比较分析涡初生时吸力面的速度流线、涡量和湍动能。对比了不同截面的物理量分布,并对不同空化条件下空化发展与TLV涡强度之间的关系进行了分析。研究表明:泄漏剪切带是形成TLV的主要区域,该区域的湍动能和涡量均较大,轴向主流与间隙射流形成对流,促进了涡的生成和发展,大间隙下的泄漏流速、涡强度与涡尺度更大;TLV核心区涡旋来自剪切带形成的剪切涡和周向的来流涡。在大空化数下,涡与空化分布基本一致,涡强度与空化正相关,叶顶涡空化在大间隙时延伸更远。在小空化数下,涡与空化位置不完全重合,空化形成所需要的涡强度较低,易扩展形成片状空化,间隙宽度对空化的影响较小。
In order to grasp the formation and evolution mechanism of the tip leakage vortex of axial flow pump,and evaluate the influence of the cavitation condition of vortex formation and the gap width,an axial flow pump clearance leakage flow experiment and numerical calculation were carried out.The three-dimensional visualization of the gap flow characteristics and the vortex structure was obtained by applying the streamline vortex cloud diagram.The distribution of the velocity streamlines,vorticity and turbulent kinetic energy on the suction surface were analyzed as the vortex at the initial generation.The physical quantity distributions of different cross-sections were compared,and the relationship between cavitation development and TLV vortex strength was analyzed for different cavitation conditions.Results showed that the leakage shear zone was the main area of TLV formation,where the turbulent kinetic energy and vorticity were large.Convection formed by the axial mainstream and interstitial jets promoted the generation and development of vortices.The intensity and scale of vortices under large clearance were larger,accompanied by greater leakage velocity.The vortex in the core area of TLV came from the shear vortex formed by the shear zone and the circumferential incoming vortex.With a large cavitation number,the vortex and cavitation distribution were basically the same,the vortex strength was positively correlated with cavitation,and the tip vortex cavitation extended farther in the large gap.With a small cavitation number,the vortex and the cavitation position did not completely overlap,and the gap width had little effect on cavitation.Due to the lower environmental pressure,the vortex strength required for cavitation formation was smaller,so it was easy to form cavitation and expand to form sheet cavitation.The TLV vortex strength was increased along the leading edge of the blade,reaching the maximum near the trailing edge,while the average vortex strength was the largest at the leading edge of the blade,where cavitation occurred first.
作者
张虎
左逢源
张德胜
施卫东
ZHANG Hu;ZUO Fengyuan;ZHANG Desheng;SHI Weidong(Research Center of Fluid Machinery Engineering and Technology,Jiangsu University,Zhenjiang 212013,China;School of Mechanical Technology,Wuxi Institute of Technology,Wuxi 214121,China;School of Mechanical Engineering,Nantong University,Nantong 226019,China)
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2021年第2期157-167,共11页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(51776087)。
关键词
轴流泵
间隙宽度
叶顶泄漏涡
涡强度
泄漏剪切带
空化
axial flow pump
gap width
tip leakage vortex
vortex strength
leakage shear zone
cavitation
