How to control the noise outside the generator room? 'Questions and Answers'

Recently, Haixing Power Technology Co., Ltd. has communicated with many customers and found that customers haveGenerator setThe noise generated was very annoying, so Haixing organized a solution based on customer questions on how to deal with it.Generator setArticle about noise in the computer room.
Question: Where does the noise in the generator room come from?
Answer: Jiangsu Haixing Power believes that diesel engine unit noise is a complex sound source composed of multiple sound sources. According to the mode of noise radiation, it can be divided into aerodynamic noise, surface radiation noise and electromagnetic noise. According to the cause of generation, diesel engine surface radiation noise can be divided into combustion noise and mechanical noise. Among them, aerodynamic noise is the main noise source.
1. Aerodynamic noise is caused by the unsteady process of gas, that is, by the disturbance of gas and the interaction between gas and objects. Aerodynamic noise radiated directly to the atmosphere, including intake noise, exhaust noise and cooling fan noise.
2. It is difficult to strictly distinguish between combustion noise and mechanical noise. The noise caused by the pressure fluctuation caused by combustion in the cylinder and radiated outward through the cylinder head, piston, connecting rod, crankshaft and body is usually called combustion noise. The noise produced by the impact of the piston on the cylinder liner and the mechanical impact and vibration of moving parts is called mechanical noise. Generally, the combustion noise of direct injection diesel engines is higher than the mechanical noise, while the mechanical noise of non-direct injection diesel engines is higher than the combustion noise. However, combustion noise is higher than mechanical noise during low-speed operation.
3. Electromagnetic noise is generated by the high-speed rotation of the generator rotor in the electromagnetic field.

Question: Since there are so many types of noise generated by generator sets, how should they be dealt with?
Answer: After years of experience of Jiangsu Haixing Power, we believe that the noise of diesel generator sets is mainly exhaust noise, and the noise is obviously low-frequency. When the noise source cannot be reduced, comprehensive management of sound insulation, sound absorption and silencing can be adopted for the diesel generator set as needed.
1. Ventilation and noise reduction of the machine room. In actual work, when considering the plan, we must not only reduce noise, but also meet the air flow required for the operation of the generator set.
(1) Air inlet silencer system of the computer room
①In order to meet the cooling air and combustion air volume required when the unit is running, the machine room is ventilated by mechanical air inlet.
② Use bricks to build two air inlets outside the computer room, and install a low-noise axial flow fan under the wall of the air inlet to supply air to the computer room.
③A large air volume combined chip muffler is installed in the air inlet duct to absorb air flow noise and mechanical noise.
④An air inlet is opened on the outer wall of the air inlet. Special aluminum alloy shutters and protective wire mesh are installed at the air inlet to prevent foreign matter from entering the air duct.
(2) Machine room exhaust silencer system
① Build two exhaust ducts with bricks outside the machine room.
②Install a large air volume combined chip muffler in each exhaust duct to absorb exhaust flow noise and mechanical noise.
③The air exhaust outlet is set right in front of the unit, and the front end of the unit's radiator is equipped with a vibration-absorbing flexible joint and an air guide expansion and silencer duct, which are connected to the heat exhaust air silencer duct.
④ Install special aluminum alloy shutters and protective wire mesh at the outlet of the exhaust duct to prevent foreign matter from entering the air duct.
(3) Unit exhaust muffler
The sound attenuation volume of the exhaust muffler randomly configured in the generator set is very small. Taking the diesel generator set produced by Taizhou Zhaohang Mechanical and Electrical Co., Ltd. as an example, it is generally 15 to 20dB (A), which cannot meet the environmental protection standards. A micro-perforated plate exhaust muffler designed for high, medium and low frequency noise was reinstalled on the exhaust pipe of the unit. It is characterized by large sound attenuation, low resistance, and high temperature resistance of materials and structures. The exhaust pipe is connected to the flue gas outlet of the unit using a metal corrugated pipe to reduce vibration noise caused by the steel connection.
2. Sound absorption in the machine room.
Since the generator room is a brick concrete structure, the sound reflection is strong. In order to achieve the sound absorption effect, sound-absorbing materials are reasonably installed on the walls and top of the computer room. The structure of the sound-absorbing layer is aluminum alloy perforated gusset plate + centrifugal sound-absorbing cotton + light steel keel + supports and hangers. The original average sound absorption coefficient α1≈0.10 in the computer room. After installing sound-absorbing materials, the average sound absorption coefficient α2≈0.75~0.85 in the computer room. The sound absorption amount can reach 9~12dB(A), and the reverberation time can be reduced to 2~ 3s. The loudness in the computer room is also greatly reduced, which changes the working conditions and improves the sound insulation performance of the computer room.
3. Sound insulation system.
In order to ensure good sound insulation performance of the computer room, a fireproof and soundproof door is installed at the connection between the computer room and the outside of the computer room, and the door seam sealing material is a rubber sealing strip. Other holes that cause sound leakage are sealed with brick walls.