Browse Publications Technical Papers 2006-01-0649
2006-04-03

Modeling of Blow-by in a Small-Bore High-Speed Direct-Injection Optically Accessible Diesel Engine 2006-01-0649

The blow-by phenomenon is seldom acquainted with diesel engines, but for a small bore HSDI optical diesel engine, the effects are significant. A difference in peak pressure up to 25% can be observed near top-dead-center. To account for the pressure differences, a 0-D crevice flow model with a dynamic ring pack model was incorporated into the KIVA code to determine the amount of blow-by. The ring pack model will take into account the forces acting on the piston rings, the position of the piston rings, and the pressure located at each region of the crevice volume at every time step. The crevice flow model takes into consideration the flow through the circumferential gap, ring gap, and the ring side clearance. As a result, the cylinder mass, trapped mass in the crevice regions, and the blow-by values are known. Validation of the crevice model is accomplished by comparing the in-cylinder motoring pressure trace with the experimental motoring data. For the combustion cases, chemical reaction is calculated using the Shell ignition model and KIVA's combustion subroutine. Pressure traces for each case show dramatic improvement with the use of the crevice flow model and reported values around 4% of blow-by was seen. One of the main causes for such high blow-by values found is attributed to the lack of an oil film layer on the surface of the cylinder wall. Without the oil film, a “wet seal” cannot be established, allowing flow to pass through the circumferential gap between the piston ring contact surface and cylinder wall liner.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

Simulation of the Piston / Cylinder Behavior for Diesel Engines

2001-01-0563

View Details

JOURNAL ARTICLE

Multi-Zone DI Diesel Spray Combustion Model for Thermodynamic Simulation of Engine with PCCI and High EGR Level

2009-01-1956

View Details

TECHNICAL PAPER

Dynamic Application of a Skeletal Mechanism for DI Diesel NOX Emissions

2001-01-1984

View Details

X