基于直流吸盘式电磁铁在通电状态下能够产生强劲吸附力及其磁性在周期性输入信号的作用下将会改变的原理，设计一种由空腔部件、连接部件和电磁部件组成的电磁合成射流激励器。采用TSI-IFA300恒温式热线风速仪和X型探针测量激励器的射流性能，研究激励器输入信号幅值和频率的影响，测量结果显示激励器在合适激励参数下能够产生平均最大吹气速度达到30 m/s以上的稳定合成射流。然后，在后台阶上游1/2台阶高度站位的下壁面，沿风洞展向以台阶高度为间距对称分布了9个激励器，并分别测量它们的射流性能。在此基础上选择展向平均射流的最佳激励频率开展了台阶高度雷诺数为42 993的后台阶分离剪切层流动控制研究，试验结果表明激励流动剪切层内的平均速度和雷诺应力增加。
Based on the principle that direct-current electro holding magnet can produce a strong adhesive force in a power-on state and its magnetic properties will be altered under the action of a periodic input signal, a type of electromagnetic synthetic jet actuator (SJA) is developed consisting of cavity, connecting and electromagnetic components. The SJA's jet performance is measured using a TSI-IFA300 constant temperature hot-wire anemometer and an X-wire probe, and effects of amplitude and frequency of the SJA input signal are investigated. Measurement indicates that a stable synthetic jet with the mean maximum blow velocity being above 30 m/s can be generated under appropriate excitation parameters. Afterwards, nine SJAs with an interval of step height are distributed symmetrically along the wind tunnel spanwise direction at 1/2 step height station upstream of the backward facing step, and their jet performances are measured individually. The optimal excitation frequency of the mean spanwise synthetic jets is employed to perform flow control of separating shear layer at step-height Reynolds number of 42 993. Experimental results show that the mean velocity and the Reynolds stress within the shear layer are increased for the excited flow.
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