Analysis of Scavenged Pre-Chamber for Light Duty Truck Gas Engine

An ongoing research and development activities on the scavenged pre-chamber ignition system for an automotive natural gas fueled engine is presented in this paper. The experimental works have been performed in engine laboratory at steady state conditions on a gas engine with 102 mm bore and 120 mm stroke, converted to a single cylinder engine. The in-house designed scavenged pre-chamber is equipped with a spark plug, fuel supply and a miniature pressure sensor for detailed combustion diagnostics. The engine was operated at constant speed, fully open throttle valve and four different fueling modes with or without spark discharge. A partly motored mode allowed direct evaluation of the pre-chamber heat release. The experimental data acquired in this research served as a validation data for the numerical simulations.

The performed tests of prototypes and calculations have recently been expanded to include 3-D flow calculations in the Ansys Fluent software. The work presents results from the coupled 1-D and 3-D numerical simulation of the flow in the pre-chamber. The main goal of the computational fluid dynamic (CFD) simulation was to describe the fluid dynamics inside the pre-chamber (without combustion), mixture distribution and assessment of the scavenging quality. The pre-chamber interior volume is analyzed in detail for the operating condition. The outputs of the simulation serve as a base for optimization of the pre-chamber design. It is also a valuable input for the optimal control setting to improve overall functionality of the scavenged pre-chamber. The simulation results were compared with the experiments.