Role of exothermic centers on knock initiation and knock damage

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5935689

Konig, G; Maly, R R; Bradley, D; Lau, A K.C.; Sheppard, C G.W.

In this paper the nature of autoignition and knocking is investigated experimentally and theoretically in an optical engine by high speed direct light photography and laser Schlieren filming. Special emphasis is devoted experimentally and theoretically to the role of exothermic centers in the end-gas in initiating knocking combustion and subsequent knock damage to the combustion chamber walls. The optical engine is a modified single cylinder ported two stroke engine equipped with a large head window for unlimited access to both the entire combustion chamber and the ring crevice region. In some experiments the formation of exothermic centers was stimulated by microscopic aluminum particles that deposited on the mirrored piston surface. The data are analyzed by numerically modelling the transition from normal combustion to autoignition with a simplified 2D-code. This code models the interactions between exothermic centers, normal combustion and the resulting time dependent fields of pressure, temperature and gas velocities. The chemico-hydrodynamic coupling is especially strong near walls where compression heating by reflected pressure waves is most effective. Thus knocking combustion is preferentially stimulated near cylinder walls. The predominant occurrence of knock damage is in the ring crevice region where knocking combustion is associated with soot formation both in the crevice and the endgas region.

• OSTI ID: 5935689
• Report Number(s): CONF-9010205--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
025000 -- Petroleum-- Combustion
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320200 -- Energy Conservation
Consumption
& Utilization-- Transportation
33 ADVANCED PROPULSION SYSTEMS
330100 -- Internal Combustion Engines
330700* -- Advanced Propulsion Systems-- Emission Control
CHEMICAL REACTION KINETICS
COMBUSTION CHAMBERS
COMBUSTION KINETICS
COMPUTER CODES
CONTROL
DATA
DATA ANALYSIS
DEPOSITS
ENGINES
EXPERIMENTAL DATA
HEAT ENGINES
IGNITION QUALITY
INFORMATION
INTERNAL COMBUSTION ENGINES
KINETICS
KNOCK CONTROL
MATHEMATICAL MODELS
NUMERICAL DATA
PISTONS
REACTION KINETICS
SOOT
TEMPERATURE GRADIENTS
TIME DEPENDENCE
TWO-DIMENSIONAL CALCULATIONS