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

2. 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 2014-10-09KTH CCGEx2

3. Motivation Turbocharger installation differs between supplier and actual engine installation This leads to different compressor characteristics Opel Ecotec 2.0 L TC 2014-10-09KTH CCGEx3

4. Question How do different intake geometries influence the surge margin? Can we explain the differences? 2014-10-09KTH CCGEx4

5. 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” 2014-10-09KTH CCGEx5

6. 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 2014-10-09KTH CCGEx6

7. 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 2014-10-09KTH CCGEx7

8. Future plans Switch to different compressor Pressure transducers in compressor walls to detect rotating instabilities On-engine validation 2014-10-09KTH CCGEx8