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Advanced Tools for Intake and Exhaust Port Design in Four Valve Spark Ignition Engines
Technical Paper
92A214
Sector:
Language:
English
Abstract
Improvements in high performance four valve spark ignition engines call for a fluid dynamic optimisation of the intake, exhaust and combustion systems. The paper presents some numerical optimisation tools for the intake and exhaust systems. The optimisation is carried out by considering the in-cylinder flow field obtained at intake valve closure. The mass of fresh air/fuel mixture trapped within the cylinder, representing the volumetric efficiency ηv of the engine, directly influences the engine power output. Furthermore, the organised motion of the air/fuel mixture is also of great relevance. The well organised tumbling motion originated by the two direct intake port of four valve engines has a strong influenced on the turbulent as well as mean flow field during combustion, thus indirectly influencing the engine power output through its influence on the combustion efficiency ηc.