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为了研究压电驱动狭缝喷口自耦合射流的流动特性,采用PIV、热线风速仪测试手段,对自耦合射流激发器在不同激励因素下的流场和速度场分布进行了实验和分析。结果显示,自耦合射流在狭缝出口处产生了反向涡对,随着自耦合射流的发展,射流呈现出在喷口短轴方向急剧向两侧扩展、而在喷口长轴方向先收缩后缓慢扩展的流动特征;自耦合射流的速度分布在法线方向呈现先上升后下降的趋势,在z/b=10左右速度达到最大值;在射流展向上,短轴方向速度呈规律的对称分布和速度自模的特征,而长轴方向速度近喷口区域呈现马鞍状分布,随着法向距离增加这种趋势消失。研究中发现,激发器存在两个谐振频率,在谐振频率激发下自耦合射流的速度和涡量比较大。与常规射流相比,自耦合射流显示出了独特的流动特性。
In order to study the flow characteristics of self-coupling jets of piezoelectric driven slit nozzle, the flow field and velocity field distribution of self-coupled jets excited by different excitation factors were experimentally analyzed with PIV and hot wire anemometer. The results show that the self-coupled jets produce reverse vortex pairs at the exit of the slits. With the development of self-coupled jets, the jet appears to expand sharply to both sides in the minor axis of the nozzle, The velocity distribution of self-coupled jets shows a tendency of first rising and then decreasing in the normal direction, reaching a maximum at about z / b = 10. In the direction of jets, the velocity in the short axis shows a regular and symmetrical distribution Speed self-mode feature, and the long axis velocity near the nozzle area showed a saddle-like distribution, with the normal distance increases this trend disappears. It is found that there are two resonant frequencies in the exciter, and the velocity and vorticity of the self-coupled jet are larger under the excitation frequency. Compared with the conventional jet, self-coupling jet shows a unique flow characteristics.