梯度结构活性碳纤维毡吸声性能分析

为研究梯度结构活性碳纤维毡的吸声性能,选取5种不同密度的粘胶基活性碳纤维毡,两两组合构成梯度结构,借助阻抗管在250~6 300 Hz频率声波范围内,对梯度结构活性碳纤维毡法向入射吸声系数进行测试,分析梯度方向、密度、结构对吸声性能的影响。结果表明:总密度相同的情况下,在低频段单一结构活性碳纤维毡吸声性能比正梯度结构好,但比倒梯度结构差,而在高频段单一结构吸声性能比正梯度结构差,但比倒梯度结构好;总密度不同的情况下,在低频段随着梯度结构总密度的增加,其吸声系数增加,而在高频段随着梯度结构第1层密度的增加,其吸声系数减小;随着活性碳纤维毡第1层密度的增加,第一共振频率向低频移动,随着总密度的增加,第一共振吸声系数增加。

Analysis on acoustic absorption performance of activated carbon fiber felts with gradient structure

In order to study the acoustic absorption properties of activated carbon fiber felts with gradient structure, five viscose based activated carbon fiber felts with different densities were selected and coupled into gradient structure. The impedance tube was used to test the normal incidence acoustic absorption coefficient of activated carbon fiber felts with gradient structure within 250-6 300 Hz accoustic waves. Factors impacting on the acoustic absorption performance of samples were explored by analyzing the effect of gradient direction, density and structures. The results show that under the same density, the acoustic absorption performance of the single structure at low frequency is better than that of the positive gradient structure, but worse than that of the inverted gradient structure. In the high frequency band, the acoustic absorption performance of the single structure is worse than that of the positive gradient structure, but better than that of the inverted gradient structure. In the case of different densities, the acoustic absorption coefficient increases as the total density of the gradient structure is increased in the low frequency band. In the high frequency band, the acoustic absorption coefficient decreases as the density of the first layer of the gradient structure is increased. As the density of the first layer increases, the first resonant frequency moves towards low direction. As the total density increases, the first resonance absorption coefficient increases.