There are some places that need to use diesel generators, so some people complain that the noise is too loud. In fact, there are many sources of noise, and there are corresponding solutions. Next, BTMA will introduce how to solve the problem of high noise of diesel generators.
Ⅰ. Sources of noise from diesel generators
1. Emanating from the engine case
The general frequency is about 500-3KHz, and the noise value varies under different engine speeds. Generally, when the speed increases by 2 times, the noise value increases by about 9-12 decibels.
2. Spill from the air inlet and outlet
There is a difference of about 10-15 decibels under no load, and the specific noise characteristic is that the noise value of the 2k-4k frequency is the largest.
3. From the engine exhaust
The difference is about 10-15 decibels with or without load, and the main frequency noise is (speed/60)x(number of cylinders/2).
4. From the cooling fan and other ancillary equipment
The noise value of this part is small compared with the above-mentioned value and can generally be ignored.
Ⅱ. Air inlet and outlet noise improvement
1. Air Vent Description
Generally, the air discharge outlet have two parts: air inlet and air discharge outlet. The air inlet (intake) is compare with the air discharge outlet (discharge outlet) because the sound is in the opposite direction to the air flow (the flow of sound is opposite to the flow of air). The noise is smaller (because the noise flows in the same direction as the air flow), about 4-7 decibels lower.
2. Use sound-absorbing boxes or sound-absorbing louvers
The length of the general silencer box is from 90-300cm in length, so its sound insulation is about 25-50 decibels (500Hz).
10-25dB (500Hz). The selection of gates needs to consider the frequency characteristics of the generator and its distance attenuation. It is best to select the appropriate silencer box and silencer louvers through trial calculations.
3. The opening of the silencer box (silencer louver)
The selection of the opening of the muffler box or the muffler louvers is determined by the flow rate and flow velocity, that is, the intake air volume Q (cms) of the generator is the information we can get from the manufacturer at the beginning. Generally, the air intake speed is V=3m/s, so the required opening area is easy to calculate.
4. Pressure loss
Excessive pressure loss will cause excessive load on the fan of the generator, or cause insufficient air intake, causing the generator to trip, so the calculation of the pressure loss needs to be very careful, and it is necessary to seek the assistance of the generator manufacturer and inform the designer The amount of pressure loss that the generator can withstand. Based on the author’s many years of experience and consulting information from various generator manufacturers, I found that the general pressure loss is within the acceptable range of 24mm Aq.
Ⅲ. Combustion exhaust outlet
Generally speaking, generator manufacturers will install exhaust mufflers at the exhaust outlet when installing generators, so this part of noise reduction only needs that the generator manufacturers specify
The above is the introduction about the excessive noise of diesel generators and how to solve this problem. If you have more questions about machinery, welcome to ask BTMA. We will try our best to help you answer.