A high-intensity infrasound generation method based on the modulated air within a closed space

A high-intensity infrasound generation method based on the air modulation technology within a closed space is studied in this paper. We designed an airflow modulator with large mass flow rate. The working mechanisms of the high-intensity infrasonic acoustic generator consisting of modulator and Helmholtz resonator were investigated by the numerical simulations, and a prototype device was manufactured in order to carry out some experiments. We calculated theoretically the sound pressure of the modulator vent under different modulator frequencies and different gas supply pressures. Furthermore, the sound intensity of the prototype generator device under different modulator frequencies and the spatial homogeneity of sound field in the test chamber were simulated. The experimental results show that the airflow modulator has stable operation performance and the prototype device can generate continuous infrasound pressure level up to 161 dB in the test chamber. Moreover, the obtained sound field is homogeneous and its signal-to-noise ratio is considerably high within the test chamber. It reveals that the design of the airflow modulator is appropriate, and the experimental results are consistent with that for the numerical simulations.