Effect of Turbulence Boundary Conditions to CFD Simulation 2011-01-0835
The CFD simulation of diesel combustion needs as accurate
initial values as possible to be reliable. In this paper the effect
of spatial distribution of state and turbulence values at intake
valve closure to those distributions prior to SOI is studied.
Totally five cases of intake and compression stroke simulations are
run. The only change between cases is the intake boundary condition
of turbulence. In the last case the average values of p, T, k, ε
and swirl number at intake valve closure are used as initial values
to compression simulation.
The turbulence in the engine cylinder is mainly generated in the
very fast flow over the intake valves. In this paper the effect of
boundary conditions of turbulence to its level at intake valve
closure is studied. Several cases are simulated with different
boundary conditions of turbulence. Also the swirl number is
compared to experimental value.
The discharge coefficients over the valves calculated from
simulation results are compared to measured values.
Simulated engine is a single-cylinder research engine is based
on a commercial 6-cylinder off-road common rail diesel engine.