Reduction of Centrifugal Blower Noise Using Active Noise Source Cancellation Method

采用主动噪声源消除方法降低离心鼓风机噪声

基本信息

批准号：
10650187
负责人：
OHTA Yutaka
金额：
$ 1.6万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

Experimental and Analytical Approach has been conducted for these three years in order to present an effective evaluation and reduction methods for aerodynamic noise radiated from widely used centrifugal type of blower.Experiments are focused on basic and higher-order of blade passing frequency (BPF) components of the radiated noise since these components show distinct peaks in power spectra and thus control the whole noise level. First, effective noise source region is experimentally determined using correlation method between the data of pressure fluctuation on the scroll surface and that of far field noise. The effective noise source region of basic BPF exists in the vicinity of the cut off apex as usually expected, while that of the higher-order BPF exists relatively downstream part on the scroll. Using this pattern of noise source distribution, active cancellation of BPF components are conducted by using piezoelectric actuators to oscillate the scroll surface directly. However, the presented active control is found to be very effective only for the higher-order BPF components because the pressure fluctuation level of basic BPF noise source is much larger than that of the secondary source. Then, another type of reduction method i.e. passive reduction method by changing geometric parameters of the blower, is necessary to have the complete noise reduction method. The passive reduction method is related to the characteristics of the noise transmission passage which is composed of some numbers of blade-to-blade passages and inlet duct. By adjusting the blade passing frequency to the maximum attenuation frequency of the frequency response function of the transmission passage, noise level of basic BPF can be reduced more than 20 decibels. The presented hybrid method of active and passive noise control is found to be effective against any types of radiated noise from centrifugal blower, and is the quite new type of noise reduction technique.

这三年进行了实验和分析方法，以便对广泛使用的离心式鼓风机辐射的气动噪声提出有效的评估和降低方法。实验集中在基本和高阶的叶片通过频率（BPF）分量辐射噪声的影响，因为这些组件在功率谱中显示出明显的峰值，从而控制整个噪声水平。首先，利用涡旋表面压力波动数据与远场噪声数据之间的相关性方法，通过实验确定有效噪声源区域。正如通常预期的那样，基本BPF的有效噪声源区域存在于截止顶点附近，而高阶BPF的有效噪声源区域存在于涡旋上相对下游的部分。利用这种噪声源分布模式，通过使用压电致动器直接振动涡旋表面来主动消除 BPF 分量。然而，我们发现所提出的主动控制仅对高阶 BPF 分量非常有效，因为基本 BPF 噪声源的压力波动水平远大于二次源的压力波动水平。那么，要想有完整的降噪方法，就需要另一种降噪方法，即通过改变鼓风机几何参数的被动降噪方法。被动降噪方法与噪声传播通道的特性有关，噪声传播通道由一定数量的叶片间通道和进气道组成。通过将叶片通过频率调节至传动通道频率响应函数的最大衰减频率，基本BPF的噪声水平可降低20分贝以上。所提出的主动和被动噪声控制混合方法对消除离心鼓风机的任何类型的辐射噪声都有效，是一种新型的降噪技术。