摘要:利用逆向工程方法,提取长耳鸮翼表面形态与构型降噪特征元素,设计仿生降噪蜗舌。将仿生降噪蜗舌应用于离心风机气流噪声控制,通过对比试验研究,在整个频段的总声压级LA均低于原型风机,声压级平均降低2.3dB;影响仿生蜗舌降噪效果的主次因素为:仿生形态单元间距t、仿生形态单元个数n、仿生形态单元高度h。基于计算气动声学原理的数值模拟分析表明,仿生系统降噪机理主要为:减小了气流对蜗舌的冲击,使蜗舌表面紊流附面层压力脉动减弱并延缓蜗舌后部涡流分离脱落;使从风机叶轮流出的脉动气流在流经仿生蜗舌表面时,流速分布较为均匀,速度突变较少,气流稳定性的增强有利于降低气流噪声的产生。
Abstract: The long-eared owl wing surface with noise reduction characteristics was remarkable influence on its flight noise,analysing the characteristic of shape and configuration by the reverse restructure technology. The design on the bionics volute tongue will control the air current noise of the centrifugal fan. Through the experimental study, the bionics volute tongue reduce air noise of centrifugal fan in entire frequency band total acoustic pressure level LA, the average sound pressure level decreased 2.3 dB. The primary and secondary influence factors of the noise reduction effect on bionics volute tongue are: non- smooth unit spacing t, non- smooth unit integer n, highly unit h. The computer simulation analysis indicated that, the bionics volute tongue surface shape noise reduction mechanism mainly is: reduced the impact of air current to the volute tongue; causes the volute tongue surface turbulent boundary pressure oscillation to weaken and to delay the eddy shedding to fall off from the tail section of the volute tongue; causes the speed of pulsating air flow on the volute tongue surface which flows out from the air blower impeller distribute even, the speed changes suddenly reduce. The flow stability enhancement is advantageous to reduce the production of the centrifugal fan air current noise.