传统电信号压力传感器受电流干扰严重,为准确地获得轴流泵内部压力脉动特性,采用高精度数字压力采集系统对一轴流泵模型的叶轮进口、导叶流道内和导叶出口进行压力测试,试验在包含马鞍区的4个流量工况(0.45Qd、0.8Qd、1.0Qd、1.2Qd)下进行.试验结果表明:在稳定工况(0.8Qd、1.0Qd、1.2Qd)下叶轮进口监测点P1的时域信号为规则的正弦波,脉动周期与叶片通过周期一致;受叶轮与导叶的动静干涉影响,导叶内部P2及出口P3均出现了小峰值的二次谐波.在非稳定工况(0.45 Qd)下各点的时域信号均出现较大峰值的二次谐波.通过快速傅里叶变换(FFT)获得了各监测点的频域结果:稳定工况下各监测点的压力脉动主频均为叶频(BPF),从叶轮进口至导叶出口幅值逐渐减小;非稳定工况下由于回流和叶顶泄漏涡等因素的影响,各监测点的频率成分复杂,主频向高频段移动且伴随有较强高频信号,脉动幅值大于其余工况.%In order to obtain the accurate characteristics of pressure fluctuation in an axial flow pump,the monitoring points of pressure were set near the impeller inlet,the blade passages and the vane outlet.The test was conducted by applying a high precision digital pressure acquisition system under 4 different flow rates,which were 0.45,0.8,1.0 and 1.2 of the design flow (Qd),respectively.Pressure fluctuations in the time domain show that:under stable conditions (0.8Qd,1.0Qd,1.2Qd),the pressure at P1 near the inlet shows a regular waveform with 3 peaks and 3 valleys as time changes,which is associated with the blade number.Due to the interaction between the rotor and the stator,the pressure at both P2 and P3 inside the vane shows a second harmonic wave with lower amplitude.While at 0.45Qd,the pressure of 3 points shows a significant second harmonic wave due to the drop of the head.Based on fast Fourier transform (FFT),the main frequency of all monitors is always the blade passing frequency (BPF) with its amplitude decreasing from the impeller inlet to the vane outlet under stable conditions.However,the unsteady flow like backflow and tip vortex at 0.45Qd lead to complex frequency components and the main frequency shifted to high frequency segment accompanied by higher amplitude.
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