Acoustics and physics
Acoustic streaming
Also known as acoustic-driven streaming.
Acoustic streaming is the steady (time-averaged) flow that an intense oscillating sound field induces in the surrounding gas or fluid. At the high SPL of an industrial sonic horn, acoustic streaming creates secondary gas circulation around obstacles that helps lift and disperse particulate already detached from a surface.
Cleaning contribution
The primary cleaning mechanism is direct acoustic vibration of the deposit. Acoustic streaming is a secondary effect: once particles are loose, the streaming flow moves them clear of the surface and into the main gas stream so they are carried out of the vessel rather than re-settling. Streaming is not the main reason a horn cleans — but it is part of why a well-placed horn keeps cleaned surfaces clean between firings.
Related terms
Related terms
- Sound pressure levelSPL is the logarithmic measure of sound pressure in decibels relative to a 20 µPa reference. Industrial sonic horns operate at 140–180 dB SPL.
- Sonic hornA sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.
- Fouling (general)Fouling is the accumulation of unwanted deposits on process-equipment surfaces. The general umbrella term covering slagging, scaling, coking, sintering and many other specific mechanisms.