应急供水多级泵意外停机水力过渡过程瞬态特性  

Transient characteristics of the hydraulic transition process of emergency water supply multi-stage pump with unexpected shutdown

作　　者：司乔瑞[1] 夏欣 武凯鹏 邓凡杰 袁寿其[1] SI Qiaorui;XIA Xin;WU Kaipeng;DENG Fanjie;YUAN Shouqi(Fluid Machinery Engineering Technology Research Centre,Jiangsu University,Zhenjiang 212013,China)

机构地区：[1]江苏大学流体机械工程技术研究中心,镇江212013

出　　处：《农业工程学报》2024年第4期72-81,共10页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家重点研发计划项目(2022YFC3204603);2022年度江苏省碳达峰碳中和科技创新专项资金(BE2022032-3);芜湖市重大科技成果工程化项目(2022zc07)。

摘　　要：应急供水多级泵的意外停机会引起系统性能参数的剧烈变化,严重威胁供水安全。为了探究多级泵停机水力过渡过程内部流场的瞬态效应,该研究建立了基于叶轮转动平衡方程的泵停机过程转速预测方法,数值模拟分析了意外停机过程中多级泵内部流动特性。研究结果表明:在意外停机过程中,多级泵分别经历水泵工况、制动工况、反转工况以及飞逸工况4个阶段,转速呈现先减小至0后沿负方向增大的趋势,最后稳定在飞逸转速-4210 r/min附近;流量呈现先减小至0后沿负方向增大的趋势,然后再沿正方向增大,最终稳定在飞逸流量-14.32 kg/s附近;扭矩呈现先减小再增加,最后减小并稳定在零点附近。泵内流量和转速的大小、方向不断变化引起叶轮流道内流体的流动分离和回流,伴随着涡的形成、发展和破碎等时空演变;熵产值的变化与多级泵内不稳定流动密切相关,由湍流耗散所带来的损失起主导作用,在达到飞逸工况后湍流耗散熵产占比约65.2%,能量损失主要发生在叶轮流道内,且制动工况中内流场的损失较大;多级泵首级流道内监测点压力变化最为剧烈,各级监测点的压力脉动系数波动幅值随着级数的增加呈减小趋势;压力脉动振幅主导频率与多级泵转速呈现正相关关系,主导分量对应于叶轮流道的叶片通过频率,且沿着流体流动方向压力脉动频率振幅逐渐增大,压力脉动的频率特性可以反应出意外停机过程中流量的不稳定变化。研究成果可为应急供水系统安全稳定运行提供理论指导。Emergency water supply is one of the most important lifeline projects for post-disaster survival support.Multi-stage pump can be the core power source for fluid transportation.A stable and reliable operation is crucial to rescue and support at disaster sites.In actual operation,the unexpected shutdown of emergency water supply multi-stage pumps can cause drastic changes in the performance parameters,such as the impeller rotating speed,flow rate,and pressure.The internal flow field in multi-stage pumps can pose a serious threat to the water supply safety.This study aims to investigate the transient response to the internal flow field during the hydraulic transition of multi-stage pump shutdown.A speed prediction was established to numerically calculate the internal flow field of the stage pump,according to the rotation balance equation of the impeller.The transient effects were analyzed from the dynamic characteristics of the impeller rotating speed,outlet flow rate,torque and the flow structures inside each stage of the impeller during the unexpected shutdown.The results indicate that the multi-stage pump shared four conditions during unplanned shutdown,pumping,braking,reversing and runaway.The rotational speed of the impeller showed a trend of first decreasing in the positive direction,and then increasing in the reverse direction,while finally stabilizing around the runaway speed of-4210 r/min.The flow rate of the pump showed a trend of first positive decrease followed by a reverse increase,then stable reverse decrease and finally stayed around the runaway flow rate of-14.32 kg/s.The torque showed a trend of positive decrease followed by a positive increase,then stable positive decrease and finally stayed near zero.The continuous changes in the magnitude and direction of flow and speed inside the pump were attributed to the flow separation and backflow inside the impeller channel,accompanied by spatiotemporal evolution,such as the formation,development and fragmentation of vortices.The entropy output value was c

关 键 词：离心泵 瞬态效应 内部流动 意外停机 熵产分析 

分 类 号：TK7333[交通运输工程—轮机工程]