双叶片离心泵自吸过程的气液流态及振动特性

Gas-liquid flow states and vibration characteristics of a double-blade centrifugal pump during self-priming process

泵的自吸过程包含着复杂的气液两相流动结构,这种不稳定的两相流动结构会诱发振动和噪声,不利于泵的稳定运行。目前,针对泵自吸过程的研究主要集中于泵的自吸机理及气液流态的演变规律,很少涉及自吸过程的振动特性。为了揭示离心泵自吸过程的振动诱导机制,通过搭建离心泵自吸性能试验装置,以双叶片离心泵为研究对象,采用高速摄影技术和振动测试技术开展自吸过程泵内气液流态及振动特性的试验研究。同时,设计5种不同位置的回流孔,研究回流孔位置对自吸性能及振动性能的影响规律。研究结果表明:自吸过程中,叶轮内部气液流动的剧烈变化加剧了叶轮转子系不稳定径向载荷,导致振动强度的增加;自吸过程中,振动激励频率分布在700 Hz~1200 Hz的中频段,并以宽频振动为主,叶轮内部存在一个明显气泡带;自吸过程结束时,首要激励频率为叶片通过频率,激励频率集中在25 Hz~400 Hz的低频段;回流孔位置对自吸时间影响显著,但是对振动强度影响较小。

The self-priming process of a pump contains a complex gas-liquid two-phase flow structure,which induces vibration and noise and is not conducive to the stable operation of the pump.At present,the research on the pump self-priming process mainly focuses on the self-priming mechanism and the evolution of the gas-liquid flow states,and rarely involves the vibration characteristics of the self-priming process.In order to reveal the vibration induction mechanism of the self-priming process of a centrifugal pump,the experimental research on the gas-liquid flow states and vibration characteristics of the pump was carried out by constructing a self-priming performance test rig with a double-blade centrifugal pump,and using high-speed photography technology and vibration testing technology.Meanwhile,five backflow holes in different positions were designed to study the effect of the position of the backflow hole on self-priming performance and vibration performance.The results show that during the self-priming process,the drastic changes in the flow of gas and liquid inside the impeller aggravate the unstable radial loads of the impeller-rotor system,resulting in an increase in vibration intensity.During the self-priming process,the vibration excitation frequency is distributed in the medium frequency band of 700 Hz-1200 Hz,and the broadband vibration is the main contributor.A big bubble inside the impeller was observed.At the end of the self-priming process,the primary excitation frequency is the blade passing frequency,with the excitation frequency concentrated in the low frequency band of 25 Hz-400 Hz.The position of the backflow hole has significant effect on the self-priming time,but less effect on the vibration intensity.