On engine turbocharger compressor surge Bertrand Kerres KTH Competence Center for Gas Exchange (CCGEx) Project duration: Jan 2013 – Dec 2017 (est) Motivation Engine at full load Design Line Surge 𝑝𝑡,𝑜𝑜𝑜 �𝑝𝑡,𝑖𝑖 Const. η Const. n Choke 𝑚̇corr • 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 2014-10-09 KTH CCGEx 2 Motivation • Turbocharger installation differs between supplier and actual engine installation • This leads to different compressor characteristics Picture: Gas stand 2014-10-09 Picture: TC on engine KTH CCGEx 3 Questions • How do different intake geometries influence the surge margin? • Can we explain the differences? 2014-10-09 KTH CCGEx 4 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” 2014-10-09 KTH CCGEx 5 Preliminary results CoV = std(𝑝2𝑐 ′)/(𝜌1 𝑈 2 ) • • 2014-10-09 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 CCGEx 6 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 2014-10-09 KTH CCGEx 7 Future plans • Switch to different compressor • Pressure transducers in compressor walls to detect rotating instabilities • On-engine validation 2014-10-09 KTH CCGEx 8