SCAVENGED PRE-CHAMBER VOLUME EFFECT ON GAS ENGINE PERFORMANCE AND EMISSIONS 2019-01-0258
This work presents development and results of experimental and numerical investigations of advanced ignition system with scavenged pre-chamber for a natural gas fueled engine with a bore of 102 mm and stroke of 120 mm. Two combustion concepts are taken into account. The lean burn concept is used to reach low engine out emissions of nitric oxides (NOx) and high thermal efficiency at low load. A stoichiometric (Lambda=1) operation, compatible with a three-way catalyst concept, at high load and potentially transient modes can provide as high as possible engine power density. The influence of the scavenged pre-chamber volume on the combustion and engine performance is presented in this paper. Two pre-chambers with different volume (2,3 % and 4,9% of compression volume) were tested at steady state conditions.
Experimental work is complemented with CFD simulations for the case of low load (lean burn concept). The size of pre-chamber was tested as well to verify CFD mode performance versus experimental data, however the main focus was put on a design of connecting channels between the pre-chamber and the main cylinder to improve mixing in the pre-chamber and combustion in the main cylinder. Different configurations were tested numerically while using multi-cycle LES calculations to select the best candidates for future testing on existing engine. These results are analyzed in terms of rate-of-heat-release and cycle-to-cycle variability.
Zbynek Syrovatka, Oldrich Vitek, Jiri Vavra, Michal Takats