NASA famously employs a sound suppression system during rocket launches to prevent the extreme pressure waves from reflecting back up off of the launch pad and damaging whatever vehicle is being launched. The system reportedly gets the job done, but nobody’s ever been very clear about how it does what it does. The above Wikipedia link doesn’t mention it, and neither does NASA’s own Space Shuttle News Reference Manual.
This video claims that the system works by having bubbles of air get pressurized by the peak pressures, converting the energy to heat which is then dissipated, I guess, to the surrounding water. I am suspicious of this explanation, since it implies that the water being sprayed all over the launch pad forms foam, i.e. bubbles of gas (air) dispersed in a liquid matrix. Rather than foam, it looks like the system is designed to generate massive quantities of aerosol, i.e. droplets of water dispersed in a matrix of air. I can then imagine two possible paths by which the sound is converted to heat:
A)The high and low temperatures associated with air pressure peaks/troughs are mitigated by direct heat transfer as these peaks/troughs pass by each water droplet;
B)The air pressure peaks/troughs drive the water droplets back and forth, inducing viscous drag whenever there is a mismatch between local air velocity and water droplet velocity; viscous drag is a lossy process that converts kinetic energy to heat.
Those are my armchair hypotheses. Can anyone point to an authoritative source (ideally NASA themselves, or a technical paper published by them) regarding the actual mechanism of sound absorption by this system?