The following describes the technical measures for noise reduction according to various noise sources: 1. Control of exhaust noise

Exhaust noise is the most energy and component part of engine noise.

Its fundamental frequency is the firing frequency of the engine, and the fundamental frequency and its higher harmonic extensions should be present in the entire exhaust noise spectrum.

The noise components mainly include the following:

a. Low-frequency pulsating noise caused by periodic exhaust;

b. The air column resonance noise in the exhaust pipe;

c. Helmholtz resonance noise of the cylinder;

d. The injection noise produced by the high-speed airflow passing through the exhaust valve annular gap and the tortuous pipe

e. Eddy current noise and exhaust system generated by the excitation of pressure wave in the pipe

The regenerative noise formed a continuous high-frequency noise spectrum with frequencies above 1000hz. As the airflow speed increases, the frequency increases significantly.

Exhaust noise is the main part of engine aerodynamic noise. Its noise one

It is generally 10-15db(a) higher than the whole engine, which is the first part of noise reduction control. Muffler is a basic method to control exhaust noise. The correct selection of muffler (or muffler combination) can reduce exhaust motor genset noise by more than 20 30db (a).

According to the principle of baudouin genset muffler, the structure of silent diesel genset muffler can be divided into resistive muffler and resistive muffler.