1. Exhaust noise:
Exhaust is a kind of high temperature, high speed pulsating gas flow noise, is the engine noise in the most energy, the most components.Exhaust noise is much higher than intake noise and mechanical noise emitted by the body.It is the main component of engine noise.Its base frequency is the ignition frequency of the engine.The main components of the exhaust noise has the following kinds: cyclical low frequency pulse noise caused by smoke, smoke the pipe of the gas column resonance noise, cylinder helmholtz resonance noise, high speed air flow through the valve clearance and zigzag line produced by noise and vortex noise and exhaust system of pressure wave in the pipe produced by regenerative noise, etc., with the increase of air velocity, noise frequency increased significantly.
2. Mechanical noise:
Mechanical noise is mainly generated by vibration or mutual impact of periodic changes of gas pressure and motion inertia force on moving parts of the engine during operation.Among them the most serious have the following kinds: the noise of piston crank connecting rod mechanism, the noise of valve mechanism, the noise of transmission gear, the mechanical vibration caused by unbalanced inertia force and noise.The strong mechanical vibration of the diesel generator set can be transmitted to the outdoor places through the foundation for a long distance, and then form noise through the radiation from the ground.This kind of structure noise propagates far, decline is reduced, once form, isolate very hard.
3. Combustion noise:
Combustion noise is the structural vibration and noise of diesel oil during combustion.Within the cylinder combustion noise sound pressure level is very high, however, most of the parts in the engine structure rigidity is higher, its natural frequency of vibration in the high frequency region, because of sonic frequency response mismatch, because of high cylinder pressure level in low frequency peak comes not smoothly, and the high frequency of cylinder pressure level is relatively easy to spread.
4. Cooling fan and exhaust noise:
The fan noise of the unit is composed of eddy current noise and rotary noise.Eddy current noise is generated when the air flow separates on the rotating blade section. It radiates an unstable flow noise due to the eddy current caused by the viscosity of the gas.Exhaust noise, air flow noise, fan noise, mechanical noise are radiated through the exhaust channel.
5. Inlet noise:
Diesel generator set in the normal operation of the time need to have enough fresh air supply, on the one hand to ensure the normal operation of the engine, on the other hand to create good heat dissipation conditions for the unit, otherwise the unit can not guarantee its performance.The air inlet system of the unit basically includes the air inlet channel and the air inlet system of the engine itself. The air inlet channel of the unit must enable fresh air to enter the machine room smoothly. Meanwhile, the mechanical noise and air flow noise of the unit can also be radiated to the outside of the machine room through this air inlet channel.
6. Generator noise:
Generator noise includes electromagnetic noise caused by magnetic field pulsation between stator and rotor, as well as mechanical noise caused by rolling bearing rotation.