摘要
通过ANSYS Fluent软件对全贯流泵装置的停机过渡过程进行研究,主要探讨了停机过程中外特性和内流场,研究发现:全贯流泵的制动工况占整个停机过程的比值最小,飞逸转速约为设计转速的84%,飞逸流量为设计流量的1.17倍。间隙回流在停机过程中的流向始终从叶轮出口流向叶轮进口,且其流量整体呈现逐渐减小的趋势。在停机过程中,轴向力整体呈现下降的趋势;转子径向力整体呈现先减小后增大的趋势;叶轮进、出口的压力脉动先减小后增大,在制动工况达到最大值后,在水轮机工况迅速减小,直至进入飞逸工况趋于稳定。叶轮进口的压力脉动幅值是泵装置内最大的,约为叶轮出口的2倍。由于受到间隙回流的影响,在叶轮进口靠近轮缘区域存在一个小型旋涡,该旋涡的范围在水泵工况先减小,在制动工况突然增大,最后在水轮机工况和飞逸工况再次减小。叶轮进口旋涡的位置受到主流流向的影响逐渐向进口导叶方向转移。全贯流泵装置内部的熵产主要集中在以叶轮为首的下游域。随着停机过程的发展,泵装置内的高熵产区域逐渐向进口导叶的方向转移,高熵产区域的范围先减小后增大。全贯流泵泵段内高熵产率区域的位置和范围与旋涡出现的位置和尺寸相对应,这表明旋涡与脱流等不良流态是导致全贯流泵段内部熵产率较高的主要原因。
The shutdown transition process of the motor-pump device was studied by ANSYS Fluent software,which mainly explored the external characteristics and internal flow field in the shutdown process.It was found that the braking condition of the motor-pump accounted for the smallest ratio of the whole shutdown process,the runaway speed was about 84%of the design speed,and the runaway flow rate was 1.17 times of the design flow rate.The flow direction of gap backflow in the shutdown process was always from the impeller outlet to the impeller inlet,and its total flow rate showed a gradually decreasing trend.During the shutdown process,the axial force as a whole showed a decreasing trend;the radial force of the rotor as a whole showed a decreasing trend and then an increasing trend;the pressure pulsation at the impeller inlet and outlet was firstly decreased and then increased,and after reaching the maximum value in the braking condition,it was rapidly decreased in the turbine condition until it entered the runaway condition and stabilized.The impeller inlet pressure pulsation amplitude was the largest in the pumping unit,about twice that of the impeller outlet.Due to the influence of the gap backflow,there was a small vortex in the impeller inlet near the rim area,the range of which was firstly decreased in the pumping condition,then suddenly increased in the braking condition,and finally decreased again in the turbine and runaway conditions.The position of the impeller inlet vortex was gradually moved towards the impeller inlet during the shutdown process.The entropy production within the motor-pump unit was mainly concentrated in the downstream region,headed by the impeller.As the shutdown process progressed,the high entropy production area inside the pump unit was gradually moved towards the inlet guide vane,and the range of the high entropy production area was firstly decreased and then increased.The location and range of the high entropy production region in the pumping section of the motor-pump corresponded to the location and size of the vortex,which indicated that the vortex and the poor flow conditions such as deliquescence were the main reasons for the high entropy production within the pumping section of the motor-pump.
作者
焦海峰
陈正国
王文
陈松山
JIAO Haifeng;CHEN Zhengguo;WANG Wen;CHEN Songshan(College of Hydraulic Science and Engineering,Yangzhou University,Yangzhou 225100,China;Jingzhou Water Conservancy and Hydropower Survey and Design Institute,Jingzhou 434000,China;College of Electrical,Energy and Power Engineering,Yangzhou University,Yangzhou 225100,China)
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2023年第9期236-245,共10页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(51076136)
江苏省自然科学基金项目(BK2008217)
江苏省水利科学与技术项目(2009053)
国家科学和技术规划项目(2006BAB04A03)
江苏省高校优势学科建设项目(PAPD)。
关键词
全贯流泵
停机过渡过程
压力脉动
涡
熵产
模型试验
motor-pump
shutdown transition process
pressure pulsation
vortex
entropy production
model test