合成射流激励器的特性及其后台阶流动控制应用

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.