变转速工况下离心泵蜗壳辐射噪声变化规律的数值研究

Numerical simulation for variation law of volute radiated noise in centrifugal pumps under variable rotating speed

以大涡模拟得到的泵内全三维非稳态流场为基础,通过设置外部监测点对声压信号进行频域分析的方法,以额定转速为1 450 r/min的离心泵为对象,基于FW-H声学模型研究了转速在1 000~6 000 r/min变化时泵内蜗壳辐射噪声的变化规律,揭示了辐射噪声与转速之间的响应关系,通过对蜗壳压力脉动强度和流场均匀性指标的分析研究,获得了转速对辐射噪声影响的根本原因。模拟结果表明:蜗壳辐射噪声随叶轮转速的增加而非线性单调增大,且在2 000~2 500 r/min的转速区间(占总区间10%)内,蜗壳辐射噪声急剧增大(增量约为额定工况噪声7%)。同时,蜗壳辐射噪声整体上呈现指向性分布,即‘正对隔舌噪声大、背对隔舌噪声小’的偏心分布。该结论可为离心泵变频运行中有效避开高辐射噪声工况提供指导,为低噪声离心泵的三维设计奠定基础。

Here, taking a centrifugal pump with a rated rotating speed of 1 450 r/min as an object, considering the 3D unsteady flow field inside the pump obtained with the large eddy simulation （LES） , setting external monitoring points and analyzing sound pressure signals in frequency domain, based on FW-H acoustic model, the variation laws of volute radiated noise in the pump were studied within a rotating speed range of 1 000-6 000 r/min. The relationship between radiated noise and rotating speed was revealed as well. Moreover, through analyzing the volute pressure fluctuation intensity and the uniformity index of the flow field, the prime causes for the effects of rotating speed on radiated noise were found. The simulation results showed that the volute radiated noise increases monotonously and nonlinearly with increase in rotating speed; the volute radiated noise grows quickly within a rotating speed rang of 2 000-2 500 r/min （10% of the whole rotating speed range） , its increment occupies 7 % of the volute radiated noise under the normal working condition; meanwhile,the overall distribution of the volute radiated noise has a directive trend, the noise is higher in the direction towards the volute tongue and it is weaker in the direction back to the volute tongue. The results provided a guide for avoiding higher noise cases when a centrifugal pump operating with variable rotating speed and laid a foundation for 3Ddesign of low-noise centrifugal pumps.