As a fundamental element of measures to reduce the carbon footprint of commercial applications, carbon-neutral fuels are increasingly coming into focus for heavy installations. In addition to diesel substitute fuels, alternative energy carriers like NG, H2, MeOH and NH3 are gaining increasing attention. The energy conversion of these fuels is typically taking place on the principle of premixed combustion, which places different demands on fuel injection and mixture formation, as compared to optimized diesel-like combustion. Accordingly, the demand to layout multi-fuel capable engine designs centers to a high share on the above-mentioned design that can burn these different fuels with high efficiency and support a high degree of commonality with the in-series engine to carry over reliable operation and to maintain attractive cost figures.
FEV has developed the Charge Motion Design (CMD) process, which can be applied to design the intake ports and combustion chambers for multi-fuel cylinder heads in the initial phase. This advanced methodology features the capabilities to predict the performance of different configurations for the various fuels based on condensed and simplified CFD simulations and dedicated post-processing routines. These correlations are tuned and calibrated to representative engine data for individual fuels to determine the characteristics.
This paper highlights the detailed application of the CMD process for cylinder head and combustion chamber definition on the base of measurements on a state-of-the-art modular single-cylinder HD engine. Six configurations of the port designs and charge motion concepts were investigated. A comparison of the concepts was first performed with the CMD fuel correlations for H2. Three concepts with varying degrees of tumble were chosen for further detailing. The results of the case study are presented along with supporting engine measurements. In addition to previously tuned correlations, new measurements with NH3 were used to calibrate and synchronize the correlations of the CMD process. A dedicated variant of the DI H2 injection in addition to the ammonia port injection was investigated as well. The CMD fuel correlations were correlated to the testing data and later applied to all configurations to evaluate their performance and suitability. This technical study highlights the potential of CMD-driven design to enable flexible, efficient, and cost-effective multi-fuel combustion.