压电驱动自耦合射流激发器影响因素

Influence Factors for Synthetic Jet Actuator Driven by Piezoelectric Membrane

利用试验研究和数值模拟的方法对压电驱动的自耦合射流激发器进行研究,通过改变激发器激励参数和几何参数探求自耦合射流的变化规律。借助于动网格技术模拟了压电驱动膜片的周期性运动,实现了自耦合射流腔体内部和外部流动的耦合计算,模拟结果获得了和试验相一致的流动现象。研究结果表明:自耦合射流沿流向中心线速度分布呈现先上升后下降的趋势,在量纲一流向距离z/b=10的地方速度达到最大值;激发器的最佳波形输入为方波,在方波信号下激发器产生的射流速度最大;自耦合射流的速度随着激发器输入电压的增大而增加,但是当电压增大到175V后这种影响趋势变得非常微弱;激发器存在两个谐振频率,分别为340Hz和1kHz,最佳谐振频率为1kHz。振幅的增大,对自耦合射流的速度提高影响显著。在条件允许下,减小腔体高度与腔体直径的比值会得到更高速度的自耦合射流。研究结果为激发器的优化设计提供了一定的理论依据。

In order to get the characteristics of flow field and the influence of some parameters of a synthetic jet, experiments and numerical simulations are performed. During the simulation, moving grid technique is used for modeling the periodic movement of the piezoelectric membrane so that the coupled computation of the field cavity and the external flow field can be realized, the flow phenomena agree well with the experiment results. The results show that： the centerline velocity of the synthetic jet takes on up-down tendency varying with the axial distances and accelerates to a maximum at a distance of approximately 10 slot-widths; the best actuating signal for synthetic jet actuator is square wave, at which the velocity of the synthetic jet can achieve to the maximum; the velocity of the synthetic jet increases with the imput voltage for actuator until it achieves 175 V; there are two resonance frequencies for actuator of the synthetic jet, 340 Hz and 1 kHz, the optimal resonance frequency is 1 kHz; The improvement of the velocity of synthetic jet is remarkably influenced by the amplitude of the actuator＇s membrane. The velocity of the synthetic jet will improve if the ratio of height to diameter of the actuator is small. The results provide theoretic foundations for the experimental parameters and the optimizing design of the experimental parts.