Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

<table class="table-group" width="800px"><tr class="fig-image" id="a"><td><img alt="473282.fig.0020a" src="https://static.hindawi.com/articles/aav/volume-2011/473282/figures/473282.fig.0020a.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(a) </b>Fan rotating speed 4000 rpm</td></tr></table></td></tr><tr class="fig-image" id="b"><td><img alt="473282.fig.0020b" src="https://static.hindawi.com/articles/aav/volume-2011/473282/figures/473282.fig.0020b.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(b) </b>Acoustic absorbent material; poal + acousticel</td></tr></table></td></tr></table>

<table>Comparison of overall fan noise reduction by three-duct liner II of AAC technology I model, AAC technology II model and AAC technology III model.</table>

Advances in Acoustics and Vibration

fig20

Figure 20

Figure 20: Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner 