LAUSR

Turbochargers increase the power density of internal combustion engines, which allows the displaced volume to be reduced and the fuel efficiency to be improved for the same level of performance. However, the demand for turbocharger centrifugal compressors to deliver increasingly elevated boost pressures, over a wide air flow range, results in unfavorable flow fields that generate narrow and broadband noises within the engine air induction system. The present study is a combined computational and experimental effort, focusing on identifying unsteady fluid-flow instabilities in a turbocharger compression system installed on a bench top stand. This work concentrates primarily on prediction of mild and deep surge instabilities, since they limit the low-flow operating range. Surge occurs near the Helmholtz resonance frequency of the compression system (including a compressor inlet duct, centrifugal compressor, compressor outlet duct, plenum, plenum outlet duct, and a valve) and results in low frequency pressur...