Dynamic Sirens

Dynamic Sirens A siren is an acoustic transmitter that operates based on bridging a flow of gas or liquid. Depending on their operation principle, there exist dynamic (rotating) and pulsating sirens. In the latter the flow is bridged with the help of a flap that performs alternate motion using a magnetic or an electrodynamic transducer. Dynamic sirens are used more commonly. There exist radial and axial dynamic sirens. In the former the flow moves along the radius perpendicularly to the axis, and in the latter - the flow movement corresponds to the rotation axis. In axial sirens a disk with holes (rotor) rotates with respect to the immovable disc (stator). In radial sirens the rotor and the stator are two coaxial surfaces (usually cylindrical). The rotor is rotated by an electric motor or turbine. The air entering the holes of the rotor and stator periodically stops, which creates compression and exhaustion in the outside environment. The sound frequency depends on the frequency of holes in the rotor and stator and the frequency of rotor's rotation. The frequency range often applied in practice is 200 Hz-100 kHz, however there are also sirens operating with the frequency of up to 600 kHz. Siren capacities can reach tens of kWts. Dynamic air sirens are used as alarms and for process purposes (coagulation of fine aerosol, elimination of foam, fog suppression, acceleration of mass exchange and heat exchange processes, etc.).