How to control the noise outside the generator room? 'Q&A'

Recently, Haixing Power Technology Company communicated with many customers and found that the customer was very upset about the noise generated by the generator set . So Haixing organized an article on how to deal with the noise in the generator set room according to the customer's question.
Q: Where does the noise in the generator room come from?
Answer: Jiangsu Haixing Power believes that diesel engine noise is a complex sound source composed of multiple sound sources. According to the noise radiation method, it can be divided into aerodynamic noise, surface radiation noise and electromagnetic noise. According to the reasons for the occurrence, the radiated noise of the diesel engine surface can be divided into combustion noise and mechanical noise. Among them, aerodynamic noise is the main source of noise.
1. Aerodynamic noise is caused by the unstable process of gas, that is, by the disturbance of gas and the interaction between gas and objects. Aerodynamic noise radiates 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 radiating outward through the cylinder head, piston, lunar shaft, and body by pressure fluctuations caused by combustion in the cylinder are usually called combustion noise. The noise generated by the impact of the piston on the cylinder liner and the mechanical impact of the 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, the combustion noise is higher than mechanical noise when running at low speed.
3. Electromagnetic noise is generated by the high speed rotation of the generator rotor in the electromagnetic field.

Q: Since there are so many types of noise generated by generator sets, how should we deal with it?
Answer: After years of experience in 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, the diesel generator set can be comprehensively treated with sound insulation, sound absorption and sound silence as needed.
1. The computer room is ventilated and sound-relieving. In actual work, we must not only reduce noise when considering the plan, but also meet the air flow required for the generator set to operate.
(1) The computer room air inlet and sound silence system
① To meet the cooling air and combustion air required for the unit's operation, the computer room uses mechanical air inlet to ventilate.
② Two air inlet ducts are built with bricks outside the computer room, and a low-noise axial flow fan is installed under the wall of the air inlet to send air into the computer room.
③ A large-volume combined plate muffler is installed in the air inlet to absorb airflow noise and mechanical noise.
④ An air inlet is opened on the outer wall of the air inlet duct, and special aluminum alloy shutters and protective wire mesh are installed at the air inlet to prevent foreign objects from entering the air inlet.
(2) Exhaust air silence system in the computer room
① Two exhaust ducts are built with bricks outside the computer room.
② Install a large air volume combined plate muffler in each exhaust duct to absorb exhaust airflow noise and mechanical noise.
③ The exhaust port is set in front of the unit, and the front end of the unit radiator is equipped with a vibration-absorbing flexible connector and a air-guided capacity expansion and silence air duct, which is connected to the hot air silence channel.
④ Special aluminum alloy shutters and protective wire mesh are installed at the outlet of the exhaust duct to prevent foreign objects from entering the air duct.
(3) The exhaust muffler
generator set randomly configured with the exhaust muffler has very small noise. Taking the diesel generator set produced by Taizhou Zhaohang Mechanical and Electrical Co., Ltd. as an example, it is generally 15~20dB (A), which cannot meet the environmental protection compliance requirements. Reinstall the micro-perforated plate exhaust muffler designed for high, medium and low frequency noise on the exhaust pipe of the unit. Its characteristics are high noise silence, low resistance, and high temperature resistance of the material and structure. The exhaust pipe is connected to the unit's flue gas outlet by metal corrugated pipe to reduce the vibration noise caused by the steel connection.
2. Absorb sound in the computer room.
Since the generator room is a brick concrete structure, the acoustic reflection is strong. In order to achieve sound absorption effect, sound absorption materials are reasonably provided on the walls and top surfaces of the computer room. The sound absorption layer structure is an aluminum alloy perforated buckle plate + centrifugal sound absorption cotton + light steel keel + support hanger. The original average sound absorption coefficient α1≈0.10 in the computer room. After the sound absorption material is installed, the average sound absorption coefficient α2≈0.75～0.85 in the computer room. Its sound absorption volume can reach 9～12dB(A), and the reverberation time can be reduced to 2～3s. The loudness in the computer room has also dropped significantly, changing the working conditions and improving the sound insulation performance of the computer room.
3. Sound insulation system.
In order to ensure good sound insulation performance in the computer room, a fire-proof sound insulation door is installed at the intersection between the computer room and the computer room, and the door joint sealing material is a rubber sealing strip. Other holes that cause leakage are blocked with brick walls.