Air intake system noise in a turbocharged petrol engine during transient operation

摘要

Engine downsizing is undertaken in the automotive industry in order to reduce the emissions and the fuel consumption of the vehicle. Turbocharging is one of the important methods to enable downsizing of the engine; 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 laboratory test conditions and may be different in the dynamic environment of the intake system during engine operation. The aim of this paper is to outline the methods used by the authors to predict and measure the turbocharger noise generation and also to understand its fundamental mechanism. A naturally aspirated car is chosen to measure the noise generated at the intake system as a starting point. Analysis methods such as STFT for the acquired data measured are explained. This will form a basis for further analysis on a turbocharged car. A simulation methodology is outlined in order to predict the noise generation mechanism. The static pressures predicted on various locations of intake system, such as upstream and downstream of compressor, are processed to obtain estimates of the sound pressure in both the frequency and the time domains. A modular turbocharger rig is designed to study the intake system dynamics during compressor surge operation and to further understand the noise generation mechanism. The paper is concluded by listing the future work planned.