Melamine Foam for Acoustic Noise Reduction in Rocket Fairings

The “shower system” on the launch tower.

When a rocket is launched, it typically emits noise of nearly 200 decibels, and in some cases as much as 220 decibels. The lethality of this level of noise is not to be underestimated, and if left unchecked, it is likely to damage our bodies, launch platforms, surrounding buildings, and so on.

Therefore, the rocket will be launched at the time of the pain of a “cold shower”, which can not only for us to cool down, but also for the rocket noise reduction.

Rocket Academy of Beijing Institute of Space Launch Technology designed a cooling and noise reduction “shower system” – large flow water spray cooling and noise reduction system.

This system is divided into two levels, a level in the launch platform layer, rocket engine ignition, will give the launch platform spray a layer of 5 cm thick water protection layer; second level in the launch platform on both sides of the 5-metre high-altitude pylons, in the rocket flew up to 5 meters high after the rocket to the rear of the arrow body flame center water spray, the two levels of spraying facilities sprayed for more than 20 seconds, spraying out 400 tons of water. The water spray is heated by sound waves, converting the energy of the sound waves into heat, thus reducing the noise at our launches to around 140 decibels and weakening the hazards of high-decibel noise.

The water comes from a large water tank on top of the launch tower, and of the 400 tons of water sprayed, 30% will be vaporized into the atmosphere, while 60% will flow away through the deflector tanks, and the evaporation of the water takes away a lot of the heat, cooling down the core area of the launch platform by around 1,000 degrees Celsius.

The “sound-absorbing equipment” in the fairing.

As the rocket rises, the airflow will cause a strong noise due to the increasing speed. Just like the usual blowing on the paper, will make the paper “pop” sound, the airflow blowing through the fairing of this large diameter, large size of the thin-walled structure, will cause more than 140 decibels of noise. Noise will destroy the fairing inside the electronic equipment and the overall structure, in particular, will cause fatigue damage to key components, greatly reducing the reliability of the entire system. Sometimes rockets undertake manned space missions, and the inside of the fairing is the spacecraft where the astronauts are, and the noise will seriously damage the health of the astronauts.

Melamine Foam for Acoustic Noise Reduction in Rocket Fairings

In response to this problem, the Overall Design Department of the Rocket Academy has developed an acoustic cover layer, which is laid on the inner wall of the fairing and covers an area of 30 square meters, with a thickness of only 4.5 centimeters.

The acoustic cover layer is mainly composed of melamine porous foam. When sound waves are incident on the surface of the porous acoustic material, part of them are reflected from the surface of the material, and the other part is transmitted to the inside of the material through the through holes that are connected to the outside world. The vibration of the sound wave into the material causes the violent movement of the air inside the through-hole, making it rub with the hole wall. Under the action of friction and viscous force, part of the acoustic energy is converted into thermal energy, so that the acoustic wave attenuation, reflected sound energy is weakened to achieve the effect of acoustic absorption. In addition, the heat exchange between the air and the hole wall and the material causes heat loss, which also causes sound energy attenuation.

EDS of SINOYQX Melamine foam

With the acoustic covering layer, the noise inside the fairing can be reduced by 5-8 dB in the frequency band above 500 Hz, and the total sound pressure level is reduced by about 3 dB. In addition to making acoustic covering layer for rockets, melamine foam can also be used for noise reduction in space shuttle, commercial aircraft, helicopters, fighters and so on.

At the same time, our scientists have taken a lot of anti-noise interference measures for spaceships as well as spacesuits. Under the multiple effects of acoustic cover layer, Helmholtz resonator, spacecraft, spacesuit, etc., the noise inside the fairing has been effectively controlled, and the hearing health of the astronauts has been reliably guaranteed.

For more information about SINOYQX melamine foam, please contact us at sales@sinoyqx.com or call us at +86-28-8411-1861.

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