Structural Flow Properties in IC Engine-Relevant Piston-Cylinder Configurations: An Eddy-Resolving Modelling Study

The feasibility of a recently developed eddy-resolving model of turbulence, termed as Very LES (Large-Eddy-Simulation), was tested by simulating the flow dynamics in two moving piston-cylinder assemblies. The first configuration deals with the compression of a tumbling vortex generated during the intake process within a cylinder with the square cross-sectional area, for which the reference experimental database was made available by Borée et al. (2002). The second piston-cylinder assembly represents a realistic motored IC-Engine (Internal-Combustion Engine) with the multiple Y-shaped intake and outtake ducts in which the movable valves are accommodated. The boundary and operating conditions correspond to the experimental study performed by Baum et al. (2014). The VLES simulation model applied presently is a seamless eddy-resolving hybrid RANS/LES (Reynolds-Averaged Navier-Stokes / Large-eddy Simulation) model. As the RANS constituent of this modelling scheme an appropriately sensitized four-equation eddy-viscosity RANS model (Hanjalic et al., 2004) is employed mimicking the dynamics of the unresolved scales. In addition to the VLES results, the background RANS model outcome has also been comparatively assessed. The result presentation encompasses the instantaneous flow fields as well as the time-averaged mean flow and turbulence intensity profiles at different time instants over the entire engine cycle.