Compressible Two-Phase Flow in Moving Domains with Applications in Blow-By Induced Fuel-in-Oil Dilution
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Some modern combustion engines use fuel injection late in the combustion cycle, leading to unburnt fuel on the cylinder wall. This fuel gets transported via the piston ring pack into the crank case, diluting and damaging the engine oil, which leads to engine damage and is a reason for more frequent oil changes. The exact transport of the fuel via the ring pack grooves and liner wall is hard to measure experimen- tally, motivating numerical simulation in early design stages for in-depth understanding of the involved processes. The flow problem at hand involves ranges of several orders of magnitude of densities, velocities and length scales, which introduces challenges in modeling and resolution. In this work, the fuel and gas flow is modeled in a two-dimensional cut of the domain, tracking the deforming fluid domain with a stabilized space-time finite element method with mesh update method. The interface of blow-by gas and oil or fuel is captured using the level-set method. Validation of the method, as well as performance results regarding mass conservation, will be presented. Our results confirm the appropriateness of the compressibility assumption and highlight the sensitivity of the oil fuel leakage regarding sealing ring movement.
