Investigation of Compressor Whoosh Noise in Automotive Turbochargers

With swelling gasoline prices, automotive OEMs have taken different approaches to improve vehicle fuel economy. One trend is to down-size the engine and to add turbo charging. One of the challenges in utilizing the turbocharger in passenger cars is to control the added NVH issues associated with this hardware, especially for the North American market where turbocharger use is scarce in gasoline engines. In this paper, the authors review an investigation on turbocharger related “whoosh” noise on a V6 engine. The whoosh noise, also called surge noise, is caused by the compressor working at or near surge conditions. Whoosh noise is a broad frequency band flow noise typically found during throttle tip-in conditions, but sometimes found even at steady state driving conditions. The root cause of whoosh noise and the detection methods are discussed in this paper. The countermeasures to reduce whoosh noises are also discussed. These countermeasures are focused on both the excitation sources and the paths. The measures to reduce excitation source include altering the compressor trim size, improving flow conditions at the compressor inlet and engine system calibration. The measures to attenuate the paths include adding air inlet resonators on both the low and high pressure sides of the compressor. Some upfront design criteria needed to avoid whoosh noise are also discussed in this paper.Cross Reference: