大小叶片贯流风机内流特性分析与实验研究

为降低空调用贯流风机的噪声,改善音质,通过采用直叶片贯流风轮达到斜扭叶片贯流风轮的音质和低噪声特性,从而降低贯流风轮的制造成本,本文设计了大小叶片交错组合的新型非等距贯流风机,并采用滑动网格对其内流特性进行了非定常数值模拟,同时对其气动噪声特性进行了实验研究.大小叶片贯流风机的偏心涡基本稳定在叶轮中心与蜗舌相连的切线上,位于叶轮内圆周附近.风轮非定常运转时,偏心涡的涡核位置在直径为2mm的圆所围成的区域内变化.大小叶片交错组合的贯流风轮改变了叶轮与蜗舌的间距,有效地降低叶片通过频率噪声并改善了音质.采用大小叶片交错组合的贯流风轮能够达到斜扭叶片贯流风机的降噪效果.

NUMERICAL ANALYSIS AND EXPERIMENT OF INTERNAL FLOW CHARACTERISTIC IN A CROSS FLOW FAN WITH DIFFERENT DIAMETER BLADES

A blade-twisted Cross-Flow-Fan (CFF) has lower noise and better tone than a straight cross flow fan.However.the price and the manufacture cost of a blade-twisted CFF are higher than that of a straight cross flow fan.In order to decrease the noise of the straight CFF and replace the blade-twisted CFF.a cross flow fan with a large diameter blade are distributed either ahead of or behind a small diameter blade is designed.The blades are also unequally distributed along the circumference.In addition.the numerical analysis and experimental research are carried out to study the internal flow characteristic in a newly designed CFF.The numerical analysis iS based on unsteady Navier-Stokes equations and moving mesh technique.The numerical results show that,the eccentric vortex core of the CFF iS located at the tangential line between the rotational eenter and the tongue of the casing.The eccentric vortex core is located near the inner circumference of the impeller.It moves within the inner area of a 2-mm diameter circle when the fan rotates unsteadily.The large and small blades change the clearance length between the impeller and the tongue of the casing when the impeller rotates.It decreases the blade passing-by-frequency noise and improves the rotating tone.The newly designed cross flow fan with difierent diameter blades decreases the aerodynamic noise of the fan.and it can achieve the noise decreasing effect of blade-twisted cross flow fan.