The droplet group microexplosions in water-in-oil emulsion sprays and their effects on diesel engine combustion

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:93161

Sheng, H Z; Chen, L; Zhang, Z P; Wu, C K ^[1]; An, C; Cheng, C Q ^[2]

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1. Chinese Academy of Sciences, Beijing (China). Inst. of Mechanics
2. Beijing Inst. of Technology (China). Dept. of Vehicle Engineering

To clarify the combustion mechanism of water-in-diesel fuel emulsion sprays and to evaluate the possible benefit of emulsions in practical usage, combustion bomb experiments, dynamic engine tests, and computer simulation were carried out, and some useful conclusions have been reached. The droplet group (lump-fashioned) microexplosions in water-in-diesel fuel emulsion sprays on an eddy-size scale during the atomization, evaporation, and combustion processes in a high-pressure, high-temperature bomb were observed with a multipulsed, off-axis, image-plane, ruby laser holocamera and a high-speed camera. The explosions eject droplet fragments from the spray region to several millimeters away, improving the fuel-air mixing process and speeding up the flame propagation. A no-water layer formed by a Hill vortex was also observed in emulsion droplets. The ambient temperature has the most important influence on the occurrence and violence of the microexplosion. Road-load-simulation engine tests were carried out on a dynamic engine test bed. The experimental results show that emulsion fuels have no significant influence on fuel consumption and reduce engine torque if no adjustment is made for the injection system, but that smoke emission is much improved when emulsion fuel is used. The combustion characteristics and the rate of heat release are also analyzed to reveal the difference between emulsion and diesel fuel. The relationships between the optimum water percentages and fuel consumption under various operating conditions were analyzed by numerical combustion modeling.

• OSTI ID: 93161
• Report Number(s): CONF-940711--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
33 ADVANCED PROPULSION SYSTEMS
COMBUSTION KINETICS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DIESEL ENGINES
DIESEL FUELS
EXPERIMENTAL DATA
FLOW VISUALIZATION
FUEL CONSUMPTION
FUEL SLURRIES
PERFORMANCE
TEST FACILITIES
WATER