摘要
为研究混流泵启动瞬态过程规律,建立了混流泵启动过程瞬态外特性和压力脉动测量系统,探究不同启动时间和不同流量下瞬态压力脉动的时频特性。通过变频器设置启动时间,分别采用LWGY-250型涡轮流量计和MPM480型压力传感器进行瞬态流量和瞬态压力测量,并基于小波变换对启动过程的非平稳压力脉动信号进行分析。研究结果表明,在启动过程中,随着泵转速增加,流量和扬程曲线均可近似分为缓慢上升、快速上升而后缓慢趋于稳定3个阶段,且每个阶段完成时间均与启动时间长短呈正相关。启动结束时刻,由角加速度与低工况运行共同引起的压力冲击现象与流量大小和启动时间有关。流量一定时,启动时间越短,压力冲击越显著;启动时间一定时,流量越大,进口压力冲击越小甚至消失,而叶轮中部与出口的压力冲击愈加明显;1 s启动且稳定工况为1.2倍设计流量时,叶轮中部与出口的最大冲击压力值分别可达37和28 kPa。对于快速启动,流量对启动过程瞬态压力变化无影响,在启动结束后流量对压力变化影响开始显现,当压力趋于平稳时,2种不同流量下叶轮中部的压力差约为30 kPa;对于慢速启动,流量对启动特性的影响在启动过程便有明显体现,在启动结束时刻,叶轮中部和出口的压力峰值均下降15 kPa。启动过程中,叶轮主频为叶频及其倍频,其变化趋势与转速变化一致。快速启动条件下,在启动结束时刻主频压力幅值存在由压力冲击造成的极大值。研究成果可为揭示瞬态运行特性及优化、设计瞬态工作水泵提供参考。
Quick start has become an inevitable requirement for pumps in many application fields.However,abnormal transient pressure and pulsation characteristics can cause start-up failures,and even safety accidents.In this study,a measurement system was established for the transient external characteristics and pressure pulsation during the start-up of mixed flow pump,in order to clarify the transient starting law of mixed flow pump.An investigation was made to explore the time-frequency characteristics of transient pressure pulsation under various start-up acceleration and flow rate,thereby analyzing the time-frequency evolution of starting process.A frequency converter was used to set the start-up time.The LWGY-250 turbine flowmeter and MPM480 pressure sensor were used to measure the transient flow and transient pressure,respectively.The wavelet transform was selected to analyze the non-stationary pressure pulsation signal during the start-up process.The results showed that the flow and head curves were approximately divided into 3 stages:a slow rise,a rapid rise,and slow flat,as the rotating speed increased during the start-up process,where the duration of 3 stages was negatively correlated with the start-up acceleration.The head curve dropped slowly and stabilized after a rapid rise until the impact head.In addition,the increase of starting acceleration had a positive stimulating effect on the external characteristics of speed,flow,and head.The pressure shock was normally caused by the angular acceleration and low-condition operation,which were related to the flow rate and start-up acceleration at the moment of the end of start-up.There was more significant pressure shock as the starting time decreased when the flow rate was constant.The inlet pressure shock weakened gradually or even disappeared,but there was a more obvious pressure shock between the middle of impeller and the outlet,as the flow rate increased,when the starting time was fixed.When the start-up time was 1 s and the stable working condition was 1.2Q,th
作者
李伟
路德乐
马凌凌
季磊磊
吴普
Li Wei;Lu Dele;Ma Lingling;Ji Leilei;Wu Pu(Research Center of Fluid Machinery Engineering and Technology,Jiangsu University,Zhenjiang 212013,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2021年第1期44-50,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金项目(51679111)
国家重点研发计划(2017YFC0403703)
江苏省重点研发计划项目(BE2017126)
江苏高校优势学科建设工程资助项目(PAPD)
江苏省现代农业装备与技术协同创新中心(4091600014)
江苏大学高级专业人才科研启动基金项目(13JDG105)。
关键词
试验
压力脉动
混流泵
启动过程
时频特性
experiment
pressure vibration
mixed-flow pump
start-up process
time-frequency characteristics
