Effect of altitude height on surface- radiated noise from diesel engines

Taking the YN4100QBZL diesel engines as the research object, acoustic power of the radiation noise from the surface of the engine has been tested and calculated, which utilizes the measuring method of superficial acoustic pressure levels based on the simulation system of atmospheric pressure. The engine´s combustion noise, mechanical noise and inlet noise have also been successfully separated with the experiment of the noise source identification of diesel engines. All the measures are taken to probe into the influencing mechanism of atmospheric pressure on surfaceradiated noise from Dl-diesel engines. Comparisons are made about the difference of combustion noise in diesel engines with and without turbocharger changed so as to obtain its variation regulation with different altitudes.