Self-support phenomenon and formation characteristics of dual synthetic jet
Self-support phenomenon and formation characteristics of dual synthetic jet
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DOI：
10.1016/j.sna.2019.111597
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
Zhiyong Liu;Zhen-bing Luo;Qiang Liu;Xiong Deng;Wen-qiang Peng
中科院分区：
文献类型：
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作者：
Zhiyong Liu;Zhen-bing Luo;Qiang Liu;Xiong Deng;Wen-qiang Peng
提出了双重合成射流的形成判据。双腔、单振膜、双出口的DSJ驱动器是一种真实的零净质量流量驱动器，具有能量利用效率高的优点。然而，DSJ特有的自支撑现象可能导致弱射流甚至无射流。采用二维数值模拟方法研究了深源结的形成特征。在分析横向运动的基础上，导出了无量纲参数Stk，并给出了射流形成判据π4a/s<Stk<K，Stk基本上表征了单腔和近场的非定常流动。通过分析归一化行程距离相对于Stk的变化趋势，可以将DSJ分为四个阶段。当Sts低于50时，射流不能形成。当Stk在50<Stk<115的范围内时，可以容易地获得射流并且大冲程距离成为可能。当Stk增大到115<Stk<420时，射流开始出现自支撑现象，射流变弱。在该阶段，拐点位于大约Stk =310处。当Stk>420时，无射流，只有回流区.对不同的速度边界条件也进行了试验，结果也符合所提出的射流形成准则。其形成准则和特点可作为DSJ的设计指导。
A formation criterion of dual synthetic jet (DSJ) is proposed. A DSJ actuator, featured by two cavities, one oscillatory diaphragm, and two exits is a real zero-net mass-flux actuator and has the superiority of higher energy utilization efficiency. However, self-support phenomenon which is unique to DSJ may result in weak jets or even no jets. Two-dimensional numerical simulations have been conducted to investigate the formation characteristics of DSJ. Based on analysis of transverse motion, a dimensionless parameterStkis drawn out as well as the jet formation criterion of π4a/s<Stk<K.Stkessentially characterizes the unsteady flow both in single cavity and in near field. By analyzing the trend of normalized stroke distance againstStk, DSJ can be classified into four stages for the covered range of simulations. WhenStkis lower than 50, jet can’t form. WhenStkis in the range of 50<Stk<115, jet can be obtained easily and large stroke distance becomes possible. However, whenStkincreases up to the range of 115<Stk<420, self-support phenomenon occurs and jet becomes weak. In this stage, an inflection point locates at aboutStk=310. No jet but a circumfluence region is available whenStk>420. A different velocity boundary condition also has been tested and the results conform to the proposed jet formation criterion too. The formation criterion and characteristics can serve as a useful design guide for DSJ.