Impact of the confinement plate on the synthetic jet

Axisymmetric synthetic jet actuators making use of loudspeakers and four lengths of the orifice with and without a confinement plate were experimentally tested and compared. The first (reference) orifice was the shortest one and was confined by the actuator wall. The next length of orifices was obtained with the use of one of three orifices' extension, with or without a confinement plate. The possibility of the use of the power factor to find the first characteristic frequency is presented. The dependence of the reaction force from the orifice length and the power is described. The time-reaction force of the actuator was measured. The actuators with a confinement plate at the time of measurements of frequency function and at the constant power generate less reaction force, as well as less velocity and efficiency, than the ones without it (even 1.8% at the characteristic frequency).