Comparison of Ring Axial Position Measurements and Simulation Results in a Large Bore Engine

Liner-piston-ring interaction is a crucial driver of blow-by emission and lube-oil consumption in internal combustion engines (ICE). It also largely influences friction losses, as up to 50 percent of the internal friction losses can be attributed to the liner-piston-ring system. A deeper understanding of this tribological system and the complex combustion process in an ICE is necessary for creating cleaner and more robust combustion engines. New ICEs must be capable of facing new industry demands, such as higher peak firing pressures and lower emissions for established and new fuels. Using simulations as an explanatory tool combined with new state-of-the-art measuring systems is fundamental for a better understanding of liner-piston-ring dynamics. Simulation tools, such as the commercial Software AVL EXCITE Piston&Rings, paired with calibration and validation, can be used to simulate the axial ring movement inside the piston grooves during the combustion cycle. The simulation is calibrated using measurements obtained from a large single-cylinder engine equipped with an LEC Smart Telemetry system. It is equipped with displacement sensors capable of measuring the distance between the ring and groove flank during engine operation. This paper compares the simulation’s ring axial position results, before and after calibration from the measurement results, with the sensor outputs and discusses the discrepancies. Ring dynamics are shown to be less stable than simulated values. The ring movement of the second ring and third ring are shown to change between cycles during similar engine operation conditions.