轴流泵装置出水流道内流脉动与流动噪声试验分析

为了研究立式轴流泵装置出水流道内流脉动及流动噪声的变化规律,采用在出水流道布置压力传感器和水听器的试验方法研究分析了轴流泵装置不同转速、不同流量时出水流道的内流脉动及流动噪声的时频特性。结果表明:相同流量比时,各监测点的脉动幅值均方根均随转速的增加而增加。相同转速时,各监测点的脉动幅值均方根均随流量比的增大而减小,不同流量比时各监测点的脉动主频存在差异性;不同转速相同流量比时同一监测点的脉动主频存在差异性;不同转速不同流量比时各监测点的脉动主频以51 Hz为主,脉动主频和脉动次主频均未与转频呈整倍数关系,脉动主频和次主频均在200 Hz范围内。相同流量比时出水流道内部流动噪声的声压级随转速的增加而增加,转速对最优工况时出水流道流动噪声的声压级影响较明显。相同转速时,出水流道内部的流动噪声随流量的增加呈先减小后增大的趋势。根据出水流道内流脉动幅值分析,应尽量避免低扬程泵装置在小流量工况运行。

Experiment Analysis on Flow-induced Pulsation and Noise in Outlet Conduit of Vertical Axial-flow Pumping System

The pressure pulsation and flow-induced noise of outlet conduit have become two of important problems which have negative effect on axial-flow pumping system reliability. In order to investigate the flow-induced noise and pressure fluctuation characteristics of outlet conduit in axial-flow pumping system under different operating conditions, the fluctuating pressure and noised signals were obtained by pressure transduces mounted at different positions and a hydrophone in middle of outlet conduit. The experimental data were further analyzed by using short-time Fourier transform method at speeds of 1450 r/min, 1800 r/min and 2200 r/min. The results showed that with the increase of rotational speed, the root mean square of the pulsating amplitude of each measuring point was increased in the same flow rate ratio. With the increase of flow rate ratio, the root mean square of pulsating amplitude was decreased for each measuring point at the same rotational speed, while there were differences in the dominant frequency of each measuring point in different flow rate ratios. The latter was adjacent to 51Hz for the same measuring point at different flow rate ratios with different rotational speeds. The dominant frequency and subdominant frequency were not multiple relation with rotational frequency. The dominant frequency and subdominant frequency was in the range of 200Hz. With the increase of rotational speed, sound pressure level of flow-induced noise was increased in the same flow rate ratio. With the increase of flow rate, the sound pressure level of flow-induced noise was decreased firstly and then increased at the same rotational speed. The rotational speed had great influence on sound pressure level of flow-induced noise under the optimal condition. The research result had reference value for study on pressure pulsation and flow-induced noise in outlet conduit of pumping system.