双吸离心泵泵站压力脉动与振动特性现场试验研究

双吸离心泵运行时,动静干涉会引起特定压力脉动,其频率为叶轮转频与叶片数相乘,即叶频。前期研究表明叶频压力脉动主要产生于压水室的隔舌区域,是引起水泵机组和泵房振动的重要激振源。为了揭示双吸离心泵系统压力脉动和振动特性的关系,开展了泵站压力脉动和振动特性的现场试验。通过在泵基础、出水管和泵房楼板位置布置振动传感器,同步测量了泵出口阀门不同开度下和泵启动开阀过程中的振动信号,借助时频分析方法开展了泵房振动信号的溯源分析。分析结果表明:在稳态工况中,水泵压力脉动和振动的相干性主要表现在转频、叶频及其倍频,且叶频压力脉动具有向上游衰减快,向下游衰减慢的特点;在启动工况中,水泵压水室压力脉动与基座(特别是垂直方向),甚至泵房出水侧楼板振动在叶频和转频处表现出相干性。根据现场测试结果认为,干室型双吸离心泵泵房在设计时,需要重点关注水泵叶频压力脉动作用下出水侧楼板等泵房结构的动力学响应问题。

Experimental investigation of pressure fluctuation and vibration characteristics of a double suction centrifugal pumping system

A specific pressure fluctuation due to the rotor-stator interaction occurs when the double suction centrifugal pump is operating,of which the frequency is the impeller rotation frequency multiplied by number of blades. Previous studies show that the blade passing frequency pressure fluctuation mainly occurs in the tongue area of the discharge chamber, which is an important reason of vibration for pump units and pump stations. In order to reveal the relationship between pressure fluctuation and vibration characteristics of double suction centrifugal pump system, field tests were carried out. By arranging vibration sensors on the pump foundation,outlet pipe and pumping house floor,the vibration signals under different opening degrees of outlet valve and during pump start-up valve opening were measured synchronously. The traceability analysis of pump station vibration signal was carried out by means of time-frequency analysis method. The results show that in the steady-state condition, the coherence of pump pressure fluctuation and vibration is mainly manifested in the rotating frequency, blade passing frequency and theirs multiple frequencies. The blade passing frequency pressure fluctuation has a rapid attenuation in the upstream and a relatively slow attenuation in the downstream; in the start-up condition, the pressure fluctuation in the pump chamber is correlated with the vibration of the base (especially in the vertical direction) and even the floor vibration at the outlet side of the pumping house at the blade passing frequency and the rotation frequency. According to the field test results, it is recommended that the dynamic response of the local structures of pumping house, such as the floor slab, excited by the blade passing frequency pressure fluctuation should be paid more attention to at the design stage of the double suction centrifugal pumping system.