立式轴流泵装置流道内流及水力噪声的数值与试验分析

Numerical and experimental analysis of flow and hydraulic noise in conduit of vertical axial-flow pump device

为探究立式轴流泵装置流道内部流动及水力噪声的分布特性,采用计算流体力学(CFD)和计算声学(CA)相结合的方法对泵装置内流场及内声场进行数值求解,并通过物理模型试验对数值计算结果的有效性给予了验证.结果表明:肘形进水流道内部流态较为平顺,流速分布较为均匀,受导叶体剩余环量的影响,水流在90°弯管内流速分布不均匀,流线呈螺旋状运动进入直管式出水流道,导致内部流态紊乱;流道内声压级和声压强峰值主要出现在叶频及其倍频处,表明叶轮的旋转是诱导流道噪声的重要原因,其中肘形进水流道总声源强度最大值位于出口处,为254.8 dB,直管式出水流道总声源强度最大值位于结构渐变段,为248.8 dB;流道内部过流断面面积的变化对流速的分量变幅有重要影响,流速的分量变幅越大,总声源强度就越大,直管式出水流道结构渐变段总声源强度相对于进口处增大了2.6%,因此在立式轴流泵装置流道优化设计时,应减少流道结构的变化.

In order to explore the distribution characteristics of flow and hydraulic noise in the conduit of a vertical axial-flow pump device,the flow field and sound field in the pump device were numerically solved by the combination of computational fluid dynamics(CFD)and computational acoustics(CA),and the effectiveness of the numerical results was verified by physical model tests.The results show that the internal flow pattern of the elbow inlet conduit is relatively smooth and the velocity distribution is relatively uniform.Affected by the residual circulation of the guide vane,the velocity distribution of the water flow in the 90°elbow is uneven,and the streamline moves spirally into the straight outlet conduit,resulting in the disorder of the internal flow pattern.The peak values of sound pressure level and sound pressure intensity in the conduit mainly appear at the blade frequency and its octave frequency,indicating that the rotation of the impeller is an important reason to induce the conduit noise.The maximum value of the total sound source intensity of the elbow inlet conduit is located at the outlet,which is 254.8 dB,and the maximum value of the total sound source intensity of the straight outlet conduit is located at the transition section of the structure,which is 248.8 dB.The change in the flow cross-sectional area of the conduit has an important impact on the component variation of flow velocity.The greater the component variation of flow velocity,the greater the total sound source intensity.Therefore,the total sound source intensity in the transition section of straight outlet conduit structure increases by 2.6%relative to the inlet.When optimizing the design of conduit of the vertical axial-flow pump device,the change of conduit structure should be reduced.