Research Article

Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

Figure 10

Variation of overall fan noise, 1st BPF, 2nd BPF, and 3rd BPF tones reduction by adaptive duct liner II of AAC technology I. Fan rotational speed 4000 rpm; acoustic measuring point 60 deg.; mobile reflective plate; parallel shift, acoustic absorbent material; poal + acousticel.
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