离心泵内双龙卷风式分离涡数值分析  

Numerical Analysis of Double Tornado-type Separation Vortices in Centrifugal Pump

作　　者：曹璞钰[1] 印刚[1] 王洋[1] 李贵东[1] 吴文[1] 

机构地区：[1]江苏大学国家水泵及系统工程技术研究中心,镇江212013

出　　处：《农业机械学报》2016年第4期22-28,共7页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家高技术研究发展计划(863计划)项目(2011AA100506);江苏省高校优势学科建设工程二期项目(PAPD)

摘　　要：为探究弯管式离心泵的内流不稳定特性,基于雷诺时均模型和旋涡判别Q准则,对离心泵设计工况下的旋涡流动进行仿真研究。基于数值计算结果,获得了叶片吸力面的拓扑结构,捕捉到驻扎于叶片上的驻脚和游离于叶轮上游的低压泡,两者共同构成了双龙卷风式分离涡。导出其基本形成机理:吸入室中的弯管流动和消旋板绕流构成了进口畸变流,包含反向涡对和低压回流。畸变流迫使进口冲角增大,吸力面发生流动分离并伴有旋涡脱落,脱落涡在回流作用下向叶轮上游运动,逐渐发展成为独立的集中分离涡,连接叶轮上游壁面与叶片吸力面。嵌入完全空化模型,证实设计工况下龙卷风式分离涡存在涡生空化特性,可能增加离心泵运行噪声。Insufficient understanding of complex flow feature in pipe-type centrifugal pump is a major problem encountered under the design condition. The inlet distorted flow of the pump duct was described,and the tornado-type vortex formation,propagation and its trigging cavitation bubble for the high noise were explained. The description and explanation were based on numerical simulations by RANS model and experiments. The mechanisms dictating the inlet distortion,including the curved duct flow,flat-plate flow and secondary vortex impacts on the incidence angle and boundary layer separation,were studied systematically. Particular attention was devoted to the notable influence of the limiting streamlines on the suction surface and pressure changes at the casing. The primary analysis identified a focus separation vortex route to the Q criterion. Like the tornado,the separation vortex had a vortex leg on the blade suction surface,and it was linked to a low pressure bubble locating ahead of the rotor. In detail,the tornado-type vortex was caused by separation at the leading edge due to high incidence. The separation gave rise to shedding of vortex from the suction surface,and consequent formation of vortex moving ahead of the rotor with the reverse flow. Moreover,another tornado-type vortex was captured standing on mid-part of the suction surface and attaching to the corner close to the shroud,due tp breakdown of former tornado-type vortex, disturbance of adjacent blade and rotation motion.Furthermore,the inlet distortion was the major factor for the complex flow in the pump. By cavitation simulation,the former tornado-type vortex and its inducing cavitation could explain the high noise under the design condition.

关 键 词：离心泵 分离涡 旋涡结构 进口畸变流 数值分析 

分 类 号：TH311[机械工程—机械制造及自动化]