Intake system acoustical analysis and noise prediction of a turbocharged diesel engine

Abstract

The acoustic characteristics of an engine intake system consisting of an intake manifold, an intercooler, a turbocharger compressor, and an air cleaner are analysed in this paper. The majority of the work in this project was focused on analysing the acoustic properties of the air cleaner of the turbocharged diesel engine and predicting the intake noise radiating from the intake snorkel. A three-dimensional computational fluid dynamic (3D CFD) approach was adopted to calculate noise transfer matrices of certain experimental acoustic loading configurations and the air cleaner by taking mean-flow effects into account. Detailed boundary condition setup in the CFD work was discussed. The sound pressure level and impedance of the engine intake noise source were first estimated by using a ‘four-load least squares method’. Then, the intake noise of the engine with the air cleaner installed was predicted based on the calculated transfer matrices and the estimated noise source. The predicted noise results of the engine with the air cleaner basically matched well with measurement, despite of some deviations at certain discrete frequencies. The 3D CFD approach was validated for further optimisation of the air cleaner for noise attenuation.