Jul. 23, 2021
Before reducing noise of diesel generator set, we should clearly know source of noise.
1.Noise source analysis of diesel generator set
A. Diesel generator set noise is a complex sound source composed of many 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 causes, the surface radiation noise of diesel engine can be divided into combustion noise and mechanical noise. Aerodynamic noise is the main noise source.
B. Aerodynamic noise is caused by the unstable process of gas, that is, the disturbance of gas and the interaction between gas and object. Aerodynamic noise radiated directly to the atmosphere, including intake noise, exhaust noise and cooling fan noise.
C. It is difficult to strictly distinguish between combustion noise and mechanical noise. Generally, the noise radiated by the pressure fluctuation formed by combustion in the cylinder through the cylinder head, piston, crankshaft and engine body is called combustion noise. The noise generated by the impact of piston on cylinder liner and the mechanical impact vibration of moving parts is called mechanical noise. Generally, the combustion noise of direct injection diesel engine is higher than the mechanical noise, while the mechanical noise of non direct injection diesel engine is higher than the combustion noise. However, the combustion noise is higher than the mechanical noise at low speed.
E. Electromagnetic noise is generated by the high-speed rotation of generator rotor in electromagnetic field.
For open type diesel generator set, it is placed indoor. Genset room will need to noise reduction. The noise reduction of the machine room needs to deal with the causes of noise respectively, mainly including the following methods:
1. Noise reduction of air inlet and exhaust: the air inlet and exhaust channels of the machine room are made into sound insulation walls respectively, and silencing sheets are set in the air inlet and exhaust channels. There is a certain distance in the channel for buffering, so as to reduce the intensity of sound source radiation from the machine room to the outside.
2. Control of mechanical noise: sound absorption and insulation materials with high sound absorption coefficient are laid on the top and surrounding walls of the machine room, which are mainly used to eliminate indoor reverberation and reduce the sound energy density and reflection intensity in the machine room. In order to prevent noise from radiating outward through the gate, set fire sound insulation iron door.
3. Control of smoke exhaust noise: the smoke exhaust system is equipped with a special secondary silencer on the basis of the original primary silencer, which can ensure the effective control of smoke exhaust noise of the unit. If the length of the smoke exhaust pipe exceeds 10m, the pipe diameter shall be increased to reduce the exhaust back pressure of the generator set. The above treatment can improve the noise and back pressure of the generator set. Through noise reduction treatment, the noise of the generator set in the machine room can meet the requirements of users outdoors.
The noise reduction of the genset room generally requires that there is enough space in the machine room. If the user cannot provide a machine room with sufficient area, the effect of noise reduction will be greatly affected. It can not only control noise, but also make the generator set work normally. Therefore, air inlet channel, exhaust channel and operation space for staff must be set in the machine room.
We suggest that after noise reduction, the diesel genset needs to operate under false load to correct the actual power of the diesel generator set (the power of the oil engine will decrease after noise reduction) to reduce and avoid accidents and improve the safety factor.
Aug. 12, 2022
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