Solutions > Ultra-silent Genset
Ultra-silent Genset
Through a comprehensive study of the genset noises, Xiamen Aosif Engineering Ltd conducts analysis of the noise source for control and has successfully developed a series of ultra-silent gensets. Here are a list of various noise sources and corresponding control programs:
1. Exhaust noise:
Exhaust is a high-temperature, high-speed impulsive air flow noise, the part of engine noise that has the largest energy and the most component. Composing the most important part of the total noise of the engine, it is much higher than the intake noise and the engine body radiated mechanical noise. Its fundamental frequency is the firing frequency of engine. The main components of exhaust noise include: low-frequency impulsive noise caused by periodic smoke extraction, air column resonance noise inside the exhaust pipe, Helmholtz resonance noise of the cylinder, noise made by high-speed air flow passing through the valve clearance and tortuous pipeline, eddy noise and the regenerated noise of the exhaust system caused under the excitation of pipe pressure wave, the noise frequency will be increased significantly as the flow velocity increases.
Disposing method: complex impedance muffler is used. The principle is to use the sound absorption characteristics of muffler materials and sound absorbing structure to attenuate the noise transmitted along the pipeline over distance to eliminate the noise. Meanwhile, with the help of the sudden expansion (or contraction) of the pipe section or connected resonator to reflect the sound waves of certain frequencies spread along the pipe at change position back to the sound source direction, so as to achieve the purpose of the noise elimination.
2. Mechanical noise: mechanical noise is mainly generated by vibration or mutual impact of the moving parts of engine during operation due to the periodic changes of gas pressure and inertia force. The most serious mechanical noises include: noise of piston crank linkage, noise of valve train, noise of transmission gear as well as vibration and noise caused by unbalanced inertial force. The strong mechanical vibration of diesel gensets can be transmitted over a long distance by the foundation to the outside around, and then formed into noise through radiation of the foundation.
Disposing method: use a built-in shock absorber or an external shock absorber to effectively isolate the transmission of genset vibration.
3. Noises of cooling fan and the exhaust: the fan noise is generated by the eddy noise and the rotation noise, the latter is caused by the periodic disturbance induced by the fan blades cutting the air flow; eddy noise is produced by the air flow separation on the rotating blade sections, that is, the swirling flow caused by the viscosity of gas caused radiates an unsteady flow noise. Exhaust noise, air flow noise, fan noise and mechanical noise will be radiated out through the exhaust duct.
Disposing method: Noise-reducing grids are installed in the exhaust duct at such an appropriate angle that the sound wave will be second cut. The grids made of acoustic wool or perforated laminated glass fiber cotton will absorb noise when receiving sound waves and the appropriate angle will prevent the sound from being directly transmitted.
5. Intake noise: Diesel genset needs adequate fresh air supply for normal operation. On the one hand, this is to ensure normal operation of the engine; on the other hand, this is to create a favorable thermal condition for the genset, otherwise the performance of genset cannot be guaranteed. The air intake system of the genset basically includes intake duct and the intake system of the engine itself. The intake duct of genst must be able to supply fresh air into the generator room smoothly, while the mechanical noise and the air flow noise of the genset can be radiated outside the room through the intake duct.
Disposing method: noise-reducing grids are installed again; optimizing intake ducts, reducing reverberation generated in the duct, improving intake louver angle of the box and reducing friction noise of the box and intake duct.
For Aosif’s ultra-silent genset, the main body of silent generator uses simulation and model experiment and data analysis, applies sound insulation, sound absorption, noise elimination and other noise control technology based on the distribution and control of sound source to make comprehensive design of the box structure for noise-reducing function. The products can be used for telecommunications, hospitals, hotels, offices, residences and other occasion having special requirements on noise control.
1. Exhaust noise:
Exhaust is a high-temperature, high-speed impulsive air flow noise, the part of engine noise that has the largest energy and the most component. Composing the most important part of the total noise of the engine, it is much higher than the intake noise and the engine body radiated mechanical noise. Its fundamental frequency is the firing frequency of engine. The main components of exhaust noise include: low-frequency impulsive noise caused by periodic smoke extraction, air column resonance noise inside the exhaust pipe, Helmholtz resonance noise of the cylinder, noise made by high-speed air flow passing through the valve clearance and tortuous pipeline, eddy noise and the regenerated noise of the exhaust system caused under the excitation of pipe pressure wave, the noise frequency will be increased significantly as the flow velocity increases.
Disposing method: complex impedance muffler is used. The principle is to use the sound absorption characteristics of muffler materials and sound absorbing structure to attenuate the noise transmitted along the pipeline over distance to eliminate the noise. Meanwhile, with the help of the sudden expansion (or contraction) of the pipe section or connected resonator to reflect the sound waves of certain frequencies spread along the pipe at change position back to the sound source direction, so as to achieve the purpose of the noise elimination.
2. Mechanical noise: mechanical noise is mainly generated by vibration or mutual impact of the moving parts of engine during operation due to the periodic changes of gas pressure and inertia force. The most serious mechanical noises include: noise of piston crank linkage, noise of valve train, noise of transmission gear as well as vibration and noise caused by unbalanced inertial force. The strong mechanical vibration of diesel gensets can be transmitted over a long distance by the foundation to the outside around, and then formed into noise through radiation of the foundation.
Disposing method: use a built-in shock absorber or an external shock absorber to effectively isolate the transmission of genset vibration.
3. Noises of cooling fan and the exhaust: the fan noise is generated by the eddy noise and the rotation noise, the latter is caused by the periodic disturbance induced by the fan blades cutting the air flow; eddy noise is produced by the air flow separation on the rotating blade sections, that is, the swirling flow caused by the viscosity of gas caused radiates an unsteady flow noise. Exhaust noise, air flow noise, fan noise and mechanical noise will be radiated out through the exhaust duct.
Disposing method: Noise-reducing grids are installed in the exhaust duct at such an appropriate angle that the sound wave will be second cut. The grids made of acoustic wool or perforated laminated glass fiber cotton will absorb noise when receiving sound waves and the appropriate angle will prevent the sound from being directly transmitted.
5. Intake noise: Diesel genset needs adequate fresh air supply for normal operation. On the one hand, this is to ensure normal operation of the engine; on the other hand, this is to create a favorable thermal condition for the genset, otherwise the performance of genset cannot be guaranteed. The air intake system of the genset basically includes intake duct and the intake system of the engine itself. The intake duct of genst must be able to supply fresh air into the generator room smoothly, while the mechanical noise and the air flow noise of the genset can be radiated outside the room through the intake duct.
Disposing method: noise-reducing grids are installed again; optimizing intake ducts, reducing reverberation generated in the duct, improving intake louver angle of the box and reducing friction noise of the box and intake duct.
For Aosif’s ultra-silent genset, the main body of silent generator uses simulation and model experiment and data analysis, applies sound insulation, sound absorption, noise elimination and other noise control technology based on the distribution and control of sound source to make comprehensive design of the box structure for noise-reducing function. The products can be used for telecommunications, hospitals, hotels, offices, residences and other occasion having special requirements on noise control.
