孔分布对多孔孔板流场和噪声的影响

Effects of hole distribution on flow field and noise for multi-hole plates

目前多孔孔板普遍采用均匀布孔结构,广泛用于管路限流降压以及减振降噪,为了进一步提高流动稳定性以及降低流噪声,在保持等效开孔直径不变的前提下,设计了具有不同孔间距、孔数和孔径的非均匀孔分布多孔孔板模型。基于数值计算结果,详细比较了含不同孔板模型管路流场中的速度、压力、回流特性、射流会聚和流动发展等流动特征。采用声学模型计算了孔板的噪声,在中心线以及垂直于流动方向的截面上设置监测点,对比了其频谱特性和总声压级。结果表明,与均匀多孔分布的常规孔板相比,孔间距等差递减、孔板边缘的孔数增多、以及孔径在满足不减少孔数的条件下增大,均能在不影响降压能力的情况下提高流动稳定性和降低板后噪声,且其噪声值分别最大改善了5.62,6.10和7.00 dB。

At present,the multi-hole plates with uniform hole distribution structure are widely used in the process industry to limit the flow and reduce the pressure,vibration and noise because of low manufacturing cost,simple structure,easy processing,easy installation and maintenance.In order to further improve the flow stability and reduce the flow noise,multi-hole plates of non-uniform hole distribution with different hole spacing,hole number,and hole diameter are designed with the equivalent opening diameter unchanged.Based on the numerical results,the velocity,pressure,reflux characteristics,jet convergence and flow development in the pipeline with different multi-hole plates are compared in detail to analyze the flow field characteristics.Moreover,the noise of multi-hole plates is numerically calculated by the acoustic analogy model.The observation points are set on the centerline and the section perpendicular to the flow direction to compare the spectrum characteristics and the overall sound pressure level.The numerical results show that the decrease of hole spacing with equal difference,the increase of hole number on the plate edge,and the increase of hole diameter without reducing the hole number can all effectively improve the flow stability and reduce the noise level of multi-hole plates without influencing the pressure drop ability compared with the general multi-hole plate with uniform hole distribution,and the maximum decrease of noise level is 5.62,6.10and 7.00 dB respectively.