Prediction and measurement of air intake noise in a turbocharged petrol engine during surge events

Turbochargers are introduced in petrol engines to facilitate downsizing and hence to reduce emissions and fuel consumption. However, increased noise is the side effect of this introduction. The noise generation is assumed to be due to the operation of turbocharger very close to the surge zone of the compressor map. For example, the compressor map is typically measured under static lab test conditions and may be different from the dynamic intake system during engine operation. The aim of the paper is to outline the methods used by the authors to predict and measure the noise generation. The static pressures predicted on various locations of intake system, such as upstream and downstream of the compressor, are processed in order to obtain the sound pressure level in both the frequency and the time domains. An experimental turbocharger rig is designed in order to verify the intake system dynamics during compressor surge and to further analyse and understand the noise generation mechanism.