EU INTERREG CEREEV Fuel Spray and Mixture Preparation in Split- Cycle Engine By Larissa R Taylor The Sir Harry Ricardo Laboratories-Centre for Automotive Engineering University of Brighton, UK September 2013
Computational Fluid Dynamics (CFD) model for engine cylinder and valves is taken from 2-ACE project: A fundamental study of the novel poppet valve 2-stroke auto ignition combustion engine http://www.brighton.ac.uk/shrl/projects/2-ace.php http://gow.epsrc.ac.uk/viewgrant.aspx?grantref= EP/F058276/1
New concept of split-cycle engine:
New concept of split-cycle engine: modelling processes in expander cylinder
For CEREEV project, the CFD model for ANSYS FLUENT simulation includes modifications to Inlet and exhaust valve timings Injector location and its type Comparison of various breakup models Boundary conditions (pressure from compression cylinder)
Intake valve opened: Compressed Air 10bar Exhaust valve closed
Direct Injection of RON95 fuel spray 95% iso-octane 5% n-heptane Mass flowrate is 0.0076 kg/s Injection velocity = 200m/s What is the optimal injector location for mixture preparation to produce the fuel vapour cloud near the spark plug?
This depends on the flow pattern for guiding fuel vapour. The transient flow in expander cylinder is calculated.
Exploring three injector locations: Near spark plug Near inlet valve Near outlet duct
Near inlet valve Mass Fraction of Octane No-break up 10
Near inlet valve Mass Fraction of Octane TAB break up 11
Near inlet valve Mass Fraction of Octane Wave break up 12
New position of injector: Near inlet valve 13
Group injectors near exhaust valve MFR of each = 0.0007642 kg/s 14
Near exhaust duct Mass Fraction of Octane No-break up 15
Near exhaust duct Mass Fraction of Octane Wave break up 16
New injector location: near spark plug 17
Near spark plug Mass Fraction of Octane No-break up 18
Injector near spark plug Mass Fraction of Octane vapour for WAVE break up model 0.16ms 19
0.2ms 20
0.3ms 21
0.4ms 22
1.2ms 23
1.8ms 24
Conclusions For the direct injection near the inlet valve, and near the exhaust duct, all CFD models showed that the fuel vapour was formed too far from the spark plug Some of the vapour is lost to the inlet duct due to reflected pressure waves. Closing the inlet valve could overcome this Exploring various flow patterns to guide the fuel spray is a key issue for a successful combustion
Conclusions The injector near the spark plug showed the fuel spray to overshoot and vapour be formed on the piston for the nobreak up CFD model The WAVE break up model showed the vapour to evaporate almost immediately in the vicinity of the spark plug Breakup spray model is a more realistic model to what would happen inside an engine. Thus having injector near spark plug would give a more successful combustion
Conclusions Further research is needed to be done to explore realistic flow patterns and injection strategies by CFD and experimental methods. But at this stage of development. What is the optimal injector location for mixture preparation near spark plug?
Near the Spark Plug 28
EU INTERREG CEREEV Fuel Spray and Mixture Preparation in Split- Cycle Engine By Larissa R Taylor The Sir Harry Ricardo Laboratories-Centre for Automotive Engineering University of Brighton, UK September 2013
Supervisors for the project: Dr Steve Begg Dr Elena Sazhina Consultants: Dr Oyuna Rybdylova Dr Daniel Coren 30
Contribution of EU INTERREG CEREEV team is gratefully acknowledged 31
Many thanks to the tutors at Park College Sussex Downs http://www.sussexdowns.ac.uk/colleges/park-college/ 32
Acknowledgements: Special thanks to STEM Sussex staff Daniel Hawkins Bronagh Liddicoat Patricia Harwood Financial help of the Nuffield Research Placement grant is gratefully acknowledged http://www.stemsussex.co.uk/index.php/secondary-fe/schoolactivities/nuffield-science-bursaries/ 33
Thank you Larissa R Taylor Park College Sussex Downs Eastbourne The Sir Harry Ricardo Laboratories Centre for Automotive Engineering