Two-dimensional visualization of premixed charge flame structure in an IC engine

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5908150

zur Loye, A O

Spark kernels and flame fronts in a premixed-charge, spark-ignition, ported engine were examined for the first time with two-dimensional spatial resolution. The most important conclusions are: (1) the flame fronts in this engine are in the reaction sheet regime; (2) the flame fronts become more convoluted and disrupted as the engine speed is increased and eventually become multiply connected in the plane of the laser sheet; (3) near the lean limit, the flame fronts become more distorted and the results strongly suggest that local extinction is taking place; (4) the turbulent flow field affects all the ignition kernels examined, which included kernels as small as 2 mm and times after ignition as short as 100 microseconds; (5) the distortion and cycle-to-cycle variation in the ignition kernel increase with engine speed; (6) the estimated increase in surface area of the flame sheet scales almost linearly with engine speed between 1200 and 2400 rpm but only a two-fold increase in the surface area of the flame sheet was observed between 300 and 1200 rpm. This agrees well with corresponding variations in combustion duration; (7) the results lend strong support to the theory that in the reaction sheet regime the increase of the turbulent flame speed over the laminar flame speed is caused primarily by an increase in the surface area of the flame sheet; (8) the thickness of the turbulent flame zone was found to increase somewhat with both mass fraction burnt and engine speed.

• Research Organization: Princeton Univ., NJ (USA)
• OSTI ID: 5908150
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330100* -- Internal Combustion Engines
ENGINES
FLAMES
FLOW VISUALIZATION
FLUID FLOW
HEAT ENGINES
IGNITION
INTERNAL COMBUSTION ENGINES
RESOLUTION
SPARK IGNITION ENGINES
SPATIAL RESOLUTION
TURBULENT FLOW