多孔蜗舌贯流风机内的非定常流动特性研究

发布时间：2018-05-01 00:40

本文选题：贯流风机 + 多孔结构　；参考：《华东理工大学》2012年硕士论文

【摘要】：近年来贯流风机的气动性能与噪声问题备受关注。本文以一种使用多孔蜗舌的贯流风机为主要研究对象,结合实验测量与数值模拟方法对其内部流场与气动噪声开展了研究。使用低压高频响压力传感器和四通道动态压力测试系统测量三种转速下风机内部四个监测点的脉动压力,以分析噪声源的特性。通过对脉动压力数据的Fourier变换,进行频谱分析得到流场中噪声源的的频谱信息。结果表明风机出口与蜗舌处的脉动压力幅值最大,为主要的噪声源。另外,频谱特性显示多孔蜗舌方案对于550～2500Hz频率段噪声有明显的改善作用。采用大涡模拟数值方法,对比研究了不同蜗舌方案的贯流风机内流特征。三维与二维数值模拟结果表明叶轮进气段及风机出口处存在大量多尺度的旋涡运动,且蜗壳后壁面易形成与叶轮旋转方向相反的大尺度涡团。通过监测点的脉动压力频谱分析,其气动噪声呈现宽频特性,且压力脉动特性与实验结果良好吻合。为了研究多孔介质对于流体发声的影响与作用机理,本文在多孔介质流动理论的基础上对Powell涡声方程修正,提出一种包含多孔介质和自由空间的Powell涡声方程通用形式,其中经典的Powell涡声方程可视为修正方程孔隙率ε=1的特殊情况。通过方程声源项的求解,对修正方程进行了初步的探讨。结合大涡模拟结果,采用FW-H积分求解方程对贯流风机的远场噪声进行了预测,比较了风机蜗舌改造前后各声源面的噪声变化情况。最后,针对多翼离心风机出口流量的不均匀性,提出并设计了一种导流板结构以调节出口流场。为了验证方案的可行性,本文对内部流场和出口总压升进行了分析,结果表明该方案能够满足设计要求。
[Abstract]:In recent years, the aerodynamic performance and noise of tubular fan have attracted much attention. In this paper, the flow field and aerodynamic noise of a tubular fan with a porous cochlear tongue are studied by means of experimental measurement and numerical simulation. In order to analyze the characteristics of noise source, the pulsating pressure of four monitoring points in the fan was measured by using a low pressure high-frequency pressure sensor and a four-channel dynamic pressure measurement system. The spectrum information of the noise source in the flow field is obtained by the Fourier transform of the pulsating pressure data. The results show that the pulsating pressure amplitude at the outlet of fan and cochlea tongue is the largest and is the main noise source. In addition, the spectral characteristics show that the porous cochlear tongue scheme can significantly improve the 550~2500Hz frequency segment noise. In this paper, the characteristics of the inner flow of the tubular fan with different cochlear tongue schemes are compared by using the large eddy simulation method. Three-dimensional and two-dimensional numerical simulation results show that there are a large number of multi-scale vortex motion in the inlet section of the impeller and the outlet of the fan, and large scale vortex clusters are easily formed on the back wall of the volute, which is opposite to the rotating direction of the impeller. Through the spectrum analysis of the pulsating pressure at the monitoring point, the aerodynamic noise shows a wide frequency characteristic, and the pressure pulsation characteristic is in good agreement with the experimental results. In order to study the effect and mechanism of porous media on the sound of fluid, the Powell vortex-acoustic equation is modified on the basis of the flow theory of porous media, and a general form of Powell vortex-acoustic equation including porous media and free space is proposed. The classical Powell vortex-acoustic equation can be regarded as a special case of modified equation porosity 蔚 ~ (1). By solving the sound source term of the equation, the modified equation is preliminarily discussed. Combined with the results of large eddy simulation, the far-field noise of the tubular fan was predicted by using the FW-H integral solution equation, and the noise changes of each sound source plane before and after the reconstruction of the fan's cochlear tongue were compared. Finally, aiming at the inhomogeneity of the outlet flow of multi-wing centrifugal fan, a flow guide plate structure is proposed and designed to adjust the outlet flow field. In order to verify the feasibility of the scheme, the internal flow field and total outlet pressure rise are analyzed in this paper. The results show that the scheme can meet the design requirements.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH432

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