射流式离心泵内场流体动力噪声特性分析

对JET750G1型射流式离心泵内场噪声进行数值计算及试验,分析该泵过流部件诱发的流动噪声和流激噪声特性。采用大涡模拟法进行不同工况的非定常数值计算,输出各过流部件表面的压力脉动作为偶极子声源。运用声学有限元方法预测流动噪声;运用声学有限元耦合结构有限元方法预测流激噪声。搭建射流式离心泵内场噪声测试系统,用水听器对泵出口的流体动力噪声进行测试,获得噪声的时域和频域信息。分析结果表明:噪声在轴频和叶频处计算和试验测试误差在4%以内;叶轮和导叶的动静干涉以及流体和结构的共振均是诱发射流式离心泵内场噪声的重要因素,过流部件自身的结构特性对内场噪声有一定影响;流动噪声整体大于流激噪声,表明内场噪声主要由流体的压力脉动特性决定;叶轮旋转偶极子声源诱发的内场噪声在轴频(47.5 Hz)处达到180 d B左右,在射流式离心泵的内场噪声中起主导作用。研究结果为射流式离心泵的低噪设计提供了参考。

Characteristic Analysis of Interior Hydrodynamic Noise in Jetting Centrifugal Pump

To analyze contribution and characteristics of interior hydrodynamic noise of the jetting centrifugal pump (JCP), the numerical calculation and experiment were carried out. Unsteady numerical calculation under different conditions were performed by using large eddy simulation (LES) method, and pressure fluctuation on the surfaces of flowing-passed components was exported as the dipole source. The flow-borne noise induced by different components of the pump was predicted by acoustic finite element method (FEM). Considering the coupling effect of sound and vibration, the weak coupling model of flow field, structure field and sound field was established to predict flow-induced structure noise generated from structural vibration. To obtain time and frequency domain information of the hydrodynamic noise in the pump outlet, a test-bed with hydrophone was built. The results showed that the maximum error between numerical calculation and experiment was 4% at major characteristic frequency. The rotor-stator interaction between impeller and vane as well as the resonance of fluid and structure was important factors of the interior noise of JCP, reflecting the structural characteristics of the flowing-passed components had some influence on the interior noise. Flow-borne noise of stators was generally greater than flow-induced structure noise, which proved interior noise was mainly determined by the pressure fluctuation characteristics of fluid. Numerical calculation and test results showed that the shaft frequency (47.5Hz) noise caused by the impeller had about 180dB and played a dominant role in the hydrodynamic noise of JCP, which provided reference and basis for hydraulic design of the low noise JCP.