Aeroacoustic characteristic of siren incentive system

Based on siren incentive system, the energy transform relationship between unsteady flow fluctuation velocity brought by siren actuator and acoustic particle velocity got by the two-microphone technique was derived. And the effect of incentive intensity, frequency, Mach number and the sensor spacing on the acoustic particle velocity was studied through the aeroacoustic characteristic experiment, verifying the theoretical model. The results are as follows: acoustic particle velocity can't be fully converted by unsteady flow fluctuation velocity, the transform relationship between velocities mentioned above is related to Mach number. Under incompressible condition, Mach number less than 0.3, the energy transform factor is proportional to the square of Mach number, and the larger Mach number means, the larger energy transform factor, and the higher conversion efficiency of unsteady flow to acoustic energy.