压电风扇非定常流场速度分布的数值研究

压电风扇利用压电材料的压电特性,将压电材料制成作动器激励薄片振动进而带动周围空气流动,可作为电子设备的散热装置。使用Fluent 商用软件,利用动网格技术模拟压电风扇产生的非定常流场。研究振动薄片的振动频率、压电风扇长度(流场长度)以及振动薄片长度与压电风扇长度的比值等参数对压电风扇出口风速的影响。研究表明:增大振动薄片的振动频率、增大压电风扇长度以及在一定范围内增大振动薄片长度与压电风扇长度的比值均能提高出口风速。振动频率与出口风速成线性关系。随着压电风扇长度的增大,出口风速提高得越来越慢。存在一个临界值,当振动薄片长度与压电风扇长度的比值大于该临界值时,出口风速随着比值的增大而下降。

NUMERICAL INVESTIGATION ON THE VELOCITY OF UNSTEADY FLOW FIELD INDUCED BY PIEZOELECTRIC FAN

Piezoelectric fans make use of the property of the piezoelectric material. The material functions as an actuator to move the plate so as to make the air around it flow. It can be an active cooling technique for electronics. The software Fluent was used with the moving-grid technique to simulate unsteady flow. The frequency of the vibrating plate, length of the piezoelectric fan (flow field's length) and the ratio of vibrating plate's length to the piezoelectric fan's are investigated to study their influence on the wind velocity at the outlet of piezoelectric fans. The results are as follows: increasing the vibrating plate's frequency, the piezoelectric fan's length, or the ratio of vibrating plate's length to piezoelectric fan's in a certain range can improve the wind velocity at the outlet. There is a linear relationship between frequency and wind velocity at the outlet. The wind velocity at the outlet improves more and more slowly with the increase of piezoelectric fan's length. There is a critical value beyond which further increase in the ratio of vibrating plate's length to the piezoelectric fan's decreases the wind velocity at the outlet.