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利用动网格技术对压电谐振风扇产生的非定常流场进行了数值模拟,以期进一步揭示压电风扇的流场特征和换热特性。研究表明:压电风扇上下两个区域均出现涡流,涡向相反(压电风扇上方为逆时针,下方为顺时针),涡对的尺度、位置和扰动范围随时间呈周期性变化规律;时均速度并非随着与压电风扇自由端距离的增大呈现单调衰减的趋势,而是在距离压电风扇自由端距离为一倍振幅的截面上出现峰值速度最大的速度分布型,该位置正是涡环达到最大型面的瞬间涡核所处位置。涡串发展、运动过程中与周围流体发生干涉融合形成的射流起到了强化换热的效果,换热效果最好的地方不是出现在平衡位置,而是涡对破碎、流体紊流度最强的地方。
The unsteady flow field generated by the piezoelectric resonant fan is numerically simulated by moving grid technology in order to further reveal the flow field characteristics and heat transfer characteristics of the piezoelectric fan. The results show that the eddy current appears in the upper and lower regions of the piezoelectric fan, with opposite vortex directions (counterclockwise above the piezoelectric fan and clockwise clockwise direction). The scale, position and disturbance range of the vortex pairs periodically change with time; The mean velocity does not tend to monotonically decrease with increasing distance from the free end of the piezoelectric fan, but the velocity profile with the highest peak velocity appears at a cross-section of one-fold the amplitude from the free end of the piezoelectric fan Is the vortex ring to the largest surface of the moment vortex core location. Vortex string development, movement and the surrounding fluid interference fusion formed jets played an enhanced heat transfer effect, the best place for heat exchange is not in the balance position, but the vortex on the broken, the most fluid turbulence local.