The aerodynamic noise generated by the centrifugal fan used in the air conditioner is related to the comfort of human living and working, which can be controlled by using the bionic design and optimization of key components of centrifugal fan. Inspired by the non-smooth leading edge of long-eared owl wing, eight kinds of volute tongues are proposed to reduce the aerodynamic noise of a centrifugal fan. The flow and sound characteristics are numerically investigated by incorporating computational fluid dynamics and computational aero-acoustics. The optimal result exhibits a noise reduction of up to 1.5 dB with a slight increase in mass flow rate. The acoustic characteristics, with respect to the sound pressure level, power spectral density, and sound directivity are discussed. The time-domain, frequency-domain, and root mean square values of pressure fluctuation are monitored and analyzed to assess the unsteady flow interaction between the volute tongue and impeller. The intensity and scale of vortices in the centrifugal fan are suppressed in the upstream and downstream of the bionic volute tongue, and the turbulence effect on the surface of the volute tongue becomes even and weak.

中文翻译：

---

仿生蜗壳舌对空调机离心风机气动性能和噪声特性的影响

空调中使用的离心式风扇产生的空气动力学噪声与人类的生活和工作舒适性有关，可以通过使用仿生设计和离心式风扇关键部件的优化来控制这种噪声。受长耳猫头鹰翅膀前缘不光滑的启发，提出了八种蜗壳舌，以减少离心风扇的空气动力噪声。通过结合计算流体动力学和计算航空声学对流动和声音特性进行数值研究。最佳结果显示噪音降低高达1.5 dB，质量流量略有增加。讨论了有关声压级，功率谱密度和声音指向性的声学特性。时域，频域，监测和分析压力波动的均方根值，以评估蜗壳舌片和叶轮之间的非定常流动相互作用。在仿生蜗壳舌的上游和下游，离心风扇中的涡流的强度和规模得到抑制，并且蜗壳舌表面上的湍流效应变得均匀而微弱。