CNG direct injection spark-ignition engine with high turbulence and high compression ratio: numerical and experimental investigations

Loic Rouleau (1, 2) , David Serrano (1, 2) , Bertrand Lecointe (1, 2) , Frédéric Ravet (3) , Gilles Coma (3) , Panos Christou (3)

1 IFPEN - IFP Energies nouvelles
2 Institut Carnot IFPEN Transports Energie
3 Technocentre Renault [Guyancourt]

This study carried on within the H2020 GasOn project scope of work showed the interest to improve the turbulence of a CNG direct injection spark ignited engine with high compression by a dedicated cylinder head design. The in-cylinder air motion was optimally configured through 3D-CFD simulation in order to cope with the high performance targets (~240 N.m/L at 1500 rpm, ~80kW/L at 4500 rpm) within the cylinder pressure limit of 160 bar (Pcylmax+2s = 180 bar). To sustain such level of pressure a Diesel engine basis was used. The compression ratio was set to 13.4:1 in line with the knock resistance of the natural gas. This newly design engine was compared to a reference engine developed in a previous study. The flow test bench measurements confirmed the high tumble level of the optimized cylinder head. This new cylinder head was next tested on a single cylinder engine equipped with high mass flow rate gas injector prototype developed by Continental. The results, integrating the boundary conditions of the air path system including LP-EGR, validated the good effect of faster combustion revealed by the lower fuel consumption and the high tolerance to EGR dilution in stoichiometric conditions. Consequently, the results showed a significant improvement compared to the previous engine and a performance attaining Diesel-like break thermal engine efficiencies (~41%).

Domaines: Sciences de l'ingénieur [physics]; Thermique [physics.class-ph]; Mécanique [physics.med-ph]

Loic Rouleau, David Serrano, Bertrand Lecointe, Frédéric Ravet, Gilles Coma, et al.. CNG direct injection spark-ignition engine with high turbulence and high compression ratio: numerical and experimental investigations. 12th Conference of Gaseous-Fuel Powered Vehicles, FKFS, Oct 2017, Stuttgart, Germany. ⟨hal-02194896⟩