Numerical simulation of the direct-injection diesel engine under motored and firing conditions
An Eulerian/Langrangian model was developed to study the two-phase flow in a two-dimensional, axisymmetric, direct-injection diesel engine, under motored and firing conditions. The liquid phase was tracked in a Lagrangian sense using discrete droplet packets (DDP). The gaseous phase was solved using an implicit, iterative, finite-difference, scheme of the control volume variety. Gaseous-phase turbulence was modeled using a compressible two-equation k/epsilon model. Turbulence effects on the liquid phase were modeled by superimposing a randomly oriented turbulent eddy velocity proportional to the root of the turbulent kinetic energy, on each packet's mean relative velocity. Droplet-droplet interactions were neglected. The general knowledge obtained during validation studies, was used to simulate the direct-injection two-stroke diesel engine under motored conditions. The simulation showed that by beginning of the injection, (15/sup 0/ before top dead center: BTDC), the large-scale gaseous motion induced during the flow-through period, had decayed to nearly unidirectionally piston driven flow, characterized by uniform levels of temperature and turbulent kinetic energy throughout the cylinder. The injection period (15/sup 0/ BTDC to 5/sup 0/ ATDC) generated substantial large scale vorticity and localized levels of turbulence an order of magnitude larger than background levels.
- Research Organization:
- Carnegie-Mellon Univ., Pittsburgh, PA (USA)
- OSTI ID:
- 5357433
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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