You may have had the experience of driving or taking a train through a tunnel. When you are in the tunnel, you will find that the noise in the tunnel is very large, so is the subway.
The reason for why there is high noise in the tunnel is that it is a closed space, when the sound propagates through the air to the tunnel wall, it will have a reflection effect, and multiple reflections will occur. These sound waves cannot be emitted, so they will generate a large vibration inside the tunnel, so you can hear the large noise.
In addition, you may also hear sound explosions. From aerodynamics, when the train passes through the tunnel quickly, it will exert a lot of pressure on the surrounding air. Since the tunnel is relatively closed, the compressed air brought out at the moment of exiting the tunnel will be rapid, so there is an explosion of sound.
Generally, there are many ways to deal with noise problems in tunnels, using absorbing materials is one of the main measures for absorbing noise. Aluminum foam is one the best materials for this solution.
We will now introduce some of the cases for the tunnel sound absorption solution.
For highway tunnel, we normally use 10mm thick perforated aluminum foam sound absorbing panels to make noise-absorbing and noise-reducing walls for the tunnels, and set 60mm thick cavities behind them, which can effectively absorb the low-frequency noise generated by automobiles. The aluminum foam material does not absorb moisture, and still maintains good sound absorption and noise reduction effects, and the aluminum foam side wall can absorb impact kinetic energy and vibration waves to protect the inner wall of the tunnel. Aluminum foam material does not corrode, burn, and is safe to use.
Such methods can also be applied to subsea tunnels. The humidity in the subsea tunnel is large, the aluminum foam material does not absorb moisture, and still maintains good sound absorption and noise reduction effects. The foam aluminum sidewall can absorb impact kinetic energy and vibration waves to protect the inner wall of the tunnel. The surface of the foam aluminum sound absorbing panel is nickel-plated and spray-coated to resist seawater corrosion.
Above cases are specific applications of aluminum foam in tunnel engineering. ALUMKING offers aluminum foam solutions for a wide range of industries. If you have any needs or ideas in this field, welcome to contact us.