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- 2015
单圆弧等厚叶片前后缘多元耦合仿生设计及降噪机理研究
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Abstract:
采用计算流体力学(CFD)方法和实验测量方法分别研究了多元耦合仿生叶片的降噪机理及其对多翼离心风机气动性能和噪声特性的影响。基于逆向工程设计方法,通过提取苍鹰翼翅前后缘典型结构特征,设计了一种前缘波形结构耦合尾缘齿形结构的仿生叶片,同时对仿生叶片和多翼离心风机用单圆弧等厚度叶片的气动性能及流动和噪声特性进行了数值分析,通过比较揭示了多元耦合仿生叶片的降噪机理,得到仿生叶片尾缘的齿形结构可改变叶片尾缘脱落涡结构和频率、前缘的非光滑波形结构可减小叶片表面脉动以及气流对叶片前缘的冲击等结果。相对于原型叶片,仿生叶片的基频和倍频均有所下降,仿生叶片的A计权声压级降低了2.1 dB。6种仿生叶片应用于多翼离心风机的实验研究表明:仿生叶片前后缘结构设计参数会影响多翼离心风机的风量、风压和噪声;采用多元耦合仿生叶片,风机噪声最大下降1.5 dB,而风机的风量和风压基本不变。
Noise？？reduction mechanism for multi？？factor coupling bionic design and the influence on aerodynamic performance and noise of multi？？blade centrifugal fan are numerically and experimentally investigated. The noise？？reduction characteristics of the leading edge and trailing edge structures of the goshawk wing are extracted, and multi？？factor coupling bionic blade with the serrated trailing edge and non？？smooth leading edge is designed by reverse reconstruction. The large eddy simulation coupled with the wall？？adapting local eddy？？viscosity model and the Ffowcs Williams？？Hawkings equation are solved to simulate the flow field and the sound field of the bionic blade. By analyzing the flow characteristics, noise reduction mechanism of bionic blade is revealed. The serrated trailing edge structure alters the vortex shedding structure of the bionic blade to reduce the continuity and the shedding frequency, while the non？？smooth leading structure effectively suppresses pressure fluctuation on blade surfaces and weakens airflow impact to leading edge of the bionic blade. Compared with the original blade, both the fundamental frequency and frequency multiplication of the bionic blade are reduced. A？？weighted sound pressure level decreases by 2.1 dB. Six kinds of blade are applied to a multi？？blade centrifugal fan, the effects of the blades with different structure parameters on the performance and noise are experimentally studied. It is found that the maximum noise of the multi？？blade centrifugal fan decreases by 1.5 dB but the flow rate and pressure remain unchanged
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