Air Induction Impact on Turbocharger Noise and Thermodynamic Performance 2020-01-0426
The trend of improved FE and performance has led to industry growth of turbocharged engines and as a result, the need to address their undesirable attributes. This presents some unique engineering challenges as customer expectations for NVH, and other vehicle-level attributes, trend higher over time as well. Noise attenuation specific to turbocharged engines is uniquely challenging due to the types of noises they produce. Of specific concern, flow interaction between the induced air and compressor through a range of thermodynamic conditions can often result in objectionable "whoosh" noises within the Air Induction System (AIS).
The traditional method for attenuation of this type of noise has been to use resonators which adds cost, weight and requires packaging space which is often at a premium in the under-hood environment. By improving our understanding of the root cause of the compressor whoosh noise, we hope to develop system design strategies that can prevent unwanted noise from being generated and avoid the need for traditional noise attenuation solutions.
To investigate different flow metrics and their impact on compressor noise and thermodynamic performance, 90 degree bends and in-flow devices were designed to test a range of swirl and flow uniformity metrics. Initial assessments were obtained from a gas stand and then verified during vehicle level testing on a gasoline turbocharged 2.0L engine in a Jeep Cherokee. Acoustic and thermodynamic gas stand characterizations were completed for 64 operating points for a set of defined configurations. Both Particle Image Velocimetry (PIV) and extensive thermal characterization were used to map inlet flow conditions into the compressor. The outcome of the investigation has shown how specific flow metrics have impacted compressor efficiency up to ~2% and noise levels up ~15 dBA at the compressor inlet.
Shadi Saeed, Brian Butler, Mark Likich, Jeff Orzechowski, Tobias Zimmermann