Sound produced by generator sets

Noise reduction for Generators

 Image

When I set out to write this blog piece I thought it would be a straightforward matter of writing a few words about sound enclosures, construction materials and noise reduction. However, when I started researching these areas I quickly realized there is too much material for a single blog to be meaningful. This is therefore the second in a series of blogs on the topic of noise reduction for generators.

Sound produced by generator sets

In this part we focus on the principal sources of noise from generators.

1 Engine mechanical noise

With the advent of high-pressure common rail fuel injection, advanced turbocharging and better combustion control, manufacturers have significantly reduced overall mechanical noise from diesel engines. The amount of sound varies with the size of the engine and its load, and can be as high as 110 dB(A) measured at one meter. Engines with more cylinders have more power strokes per revolution and therefore deliver a smoother flow of power with less vibration. Smaller engines tend to be harsher in operation and produce more noise and vibration for their size.

2 Exhaust noise

Engine exhaust is a major contributor to overall sound levels. When measured without an exhaust silencer noise can be 120 dB(A) or more depending on the size of the engine. The sound level can be reduced by up to 40 dB(A) depending on the silencer employed.

3 Cooling fan noise

Sound emanates from turbulent air as the cooling fan moves air across the engine and through the radiator. The amount of sound varies with the speed and volume of air being moved as well as with the design and distortion of the fan blades. The amount of sound can be as high as 95 dB(A) at one meter.

4 Alternator noise

The alternator has an internal cooling fan, and the combination of cooling air movement and brush friction produces noise. However, the sound level is always small compared to the driving engine.

5 Induction noise

Current fluctuations in the alternator windings create mechanical noises that add to total noise when load demand changes.

6 Structural/mechanical noise

This is caused by mechanical vibration of various structural parts and components that is radiated as sound. Isolators between the engine, alternator, controls and other components help to reduce the amount of vibration that gets converted to noise. Anti-vibration mounts can also be employed to reduce noise propagation through the ground or hull where the generator is located.

Summary

In this second blog we have discussed the main causes of noise levels in diesel generators. In the next blog piece we will discuss methods for reducing these levels.

References

Advertisements

Tags: , ,

About partsandpower

Parts & Power is the premier supplier of Marine and Industrial equipment and spare parts in the Caribbean.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s

%d bloggers like this: