On engine turbocharger compressor surge Bertrand Kerres KTH Competence Center for Gas Exchange (CCGEx) Project duration: Jan 2013 – Dec 2017 (est)

Motivation Choke Surge Const. n Const. η Design Line Downsizing to reduce friction losses Surge limits the compressor operating range at low mass flows Engine BMEP at low speeds can be limited by compressor surge Engine at full load KTH CCGEx2

Motivation Turbocharger installation differs between supplier and actual engine installation This leads to different compressor characteristics Opel Ecotec 2.0 L TC KTH CCGEx3

Question How do different intake geometries influence the surge margin? Can we explain the differences? KTH CCGEx4

Method Cold gas stand Different intake geometries: -Straight -90 deg. bend different distances bend - compressor with sharp and mild curvature relative angle to volute outlet Glass pipe in order to visualize inlet flow field -Planned LDV -“Snusk” KTH CCGEx5

Preliminary results Surge criterion: Relative pressure fluctuations at the outlet Map for sharp 90 deg. bend shows clearly different surge line than given by the supplier KTH CCGEx6

LDV ? Oil ring from compressor bearing shows swirling reverse flow during operation in or close to surge Interaction with Dean vortices from the 90 deg. bend KTH CCGEx7

Future plans Switch to different compressor Pressure transducers in compressor walls to detect rotating instabilities On-engine validation KTH CCGEx8