Search Results

Dielectric barrier discharge (DBD) was applied to control the pressure-rise rate of homogeneous compression ignition, which is an important obstacle for homogeneous charge combustion engines. DBD can produce nonthermal plasmas and has been generated in air/fuel mixtures to reform some of the fuel molecules found in such mixtures. This generally shortens the ignition delay of compression ignition of the air/fuel premixture. Stratification of the reformed premixture in the combustion chamber was achieved by pulsed DBD irradiation during the induction process. The formation of inhomogeneous distribution of the reformed premixture is expected by the formation of discharge at the end of the intake processes. A demonstrative experiment was conducted by using a rapid compression and expansion machine. A simple plasma reactor was developed and installed at the intake tube. High-voltage, high-frequency pulses were applied to form plasmas. n-Heptane was used as fuel.

Single-excite dual-fluorescence PLIF was applied to a diesel spray of a two-component fuel, the components of which have different boiling points. The spray was formed by injecting fuel into a constant-volume vessel under high-temperature, high-pressure conditions. The fluorescence emitted from the two tracers for the fuel was optically separated to measure the concentration of each component. Mixture formation was investigated based on the concentration distributions of each fuel component. The fuel concentration was derived based on the change in fluorescence intensity due to temperature and the assumption of adiabatic mixing of fuel and the surrounding fluid. The variation in the mixture distribution due to differences in the vaporization characteristics was investigated, and the results revealed that the two components have similar distribution. The concentration of the high-boiling-point component increased upstream region in a spray.