Numerical and Experimental Analysis of Intake Flow Structure and Swirl Optimization Strategies in Four-Valve Off-Highway Diesel Engine 2019-26-0042

Future emission limits for off-highway application engines need advanced power train solutions to meet stringent emissions legislation, whilst meeting customer requirements and minimizing engineering costs. DI diesel engines with four valves per cylinder are widely used in off- highway applications because of the fundamental advantages of higher volumetric efficiency, lower pumping loss, symmetric fuel spray & distribution in combination with the symmetric air motion which can give nearly optimal mixture formation and combustion process. As a result, the fuel consumption, smoke levels and exhaust emissions can be considerably reduced.

In particular, the four-valve technology, coupled with mechanical low pressure and electronic high pressure fuel delivery systems set different requirements for inlet port performance. In the present paper four valve intake port design strategies are analysed for off highway engine using mechanical fuel injection systems. Different intake port designs are experimentally evaluated on steady state flow test rig using AVL paddle wheel method for swirl and flow coefficient performance. A detail numerical analysis is carried out using AVL FIRE CFD simulation software to study effect of offset fire deck chamfer at cylinder head bottom face on velocity and pressure field which cannot be gained through experimental way. Moreover, the impact of design of directed port on in-cylinder flow field is studied through CFD simulation and the design is optimized to achieve higher swirl targets suitable to requirements of mechanical fuel injection system. Thus, two different approaches are numerically analysed and a promising design concepts are derived to raise the intake port performance for four valve intake port configuration.