Experimental study on unsteady loads of a synthetic jet at airfoil trailing edge---B:analysis of unsteady aerodynamic loads

A low frequency high power synthetic j et actuator is designed to study the effects of the synthetic jet near the trailing edge of NACA0015 airfoil.The effect of the spout speed,fre-quency and other parameters on the aerodynamic loads can be studied by changing the ground cyl-inder stroke or the operating frequency of the motor.The experimental results show that the in-teraction of the synthetic jet with the upstream can modify the aerodynamic loads obviously.If one jet works,the loads amplitude in the “blowing”process is about 3 times of that in the “suck-ing”process.Moreover,when two jets work,the amplitudes of lift and moment coefficients are not simply the sum of relevant amplitudes of the one jet case,but lie between the amplitudes of one jet work and two jets work sum.The amplitudes of the lift and momentum coefficients show a good proportional relation to the amplitude of the jet velocity,and the amplitudes of the loads decrease with the increase of the reduced frequency.When the stroke of the synthetic jet is fixed, changing the rotate speed of the servomotor,there is a linear relation between the amplitude of the loads coefficients and the rotate speed.