Infrasound generating device based on a displacement-feedback type vibration exciter

An infrasound generating device based on a displacement-feedback type vibration exciter comprising:

• a displacement-feedback type vibration exciter system, an infrasound generating chamber and a laser vibrometer measuring the vibration displacement of the displacement-feedback type vibration exciter, wherein standard infrasonic pressure generated in the infrasound generating chamber is calculated through vibration displacement measured by the laser vibrometer:
• p
• =
• π
• ⁢
• ⁢
• γ
• ⁢
• ⁢
• P
• 0
• ⁢
• d
• 2
• ⁢
• x
• 4
• ⁢
• V
• 0
• ,
• where p is sound pressure;
• y is specific heat ratio of the air;
• P0 is static pressure;
• d is diameter of a piston;
• x is displacement of the piston;
• V0 is volume of the airtight chamber when the piston is at its equilibrium position;
• the displacement-feedback type vibration exciter system comprising a signal generator, a power amplifier, a vibration exciter and a displacement-feedback component;
• the displacement-feedback component comprising a displacement sensor measuring the displacement of a moving part of the displacement-feedback type vibration exciter, a comparator comparing a displacement signal with a standard signal produced by the signal generator to obtain the deviation between the standard signal and the displacement signal and a controller processing a deviation signal, a signal conditioning circuit being adopted between the displacement sensor and the comparator to process the displacement signal;
• the moving part of the displacement-feedback type vibration exciter being driven by the controller and the power amplifier being adopted between the controller and the displacement-feedback type vibration exciter to amplify an output control signal of the controller;
• the vibration exciter being equipped with an optical channel allowing a measurement beam of the laser vibrometer to travel through and a reflector reflecting the measurement beam back to the laser vibrometer, the measurement beam injecting into the vibration exciter from the exciter end and the reflector being attached to a back end of the moving part of the vibration exciter;
• and
• the infrasound generating chamber being airtight and the piston operatively fitting in the chamber, the piston being tightly connected with a front end of the moving part of the vibration exciter and an infrasonic sensor to be calibrated being installed inside the infrasound generating chamber.