Papers by Author: Yu Juan Li

Abstract: Methanol and diesel are almost not soluble, which greatly limits the further study and popularization of the methanol-diesel fuel. To study the emission and combustion characteristics, the 4100 turbocharged and intercooled diesel engine was fueled with 0# diesel and M10 with different additives in the experiment. The result shows that, the maximum cylinder pressure and the peak of the heat release rate in the initial stage of combustion for M10 with iso-octanol and isooctyl nitrate as additive are higher than that of diesel, while the soot emission is lower and NOx emission is slightly higher than diesel’. The maximum cylinder pressure and the heat-release peak in the initial stage of combustion for M10 with dimethyl ether as additive are both lower than diesel’, and the NOx and soot emissions are obviously decreased. The power of the two blend fuels is lower than that of diesel but the magnitude is small, meanwhile the HC emission is slightly increased, while the CO emission is little declined.

Abstract: An experimental investigation was conducted on 4100 engine to study the influences of different percentages of methanol in DME/diesel blended fuel on combustion and emission performance. The result indicates that a certain amount of methanol in DME/diesel blended fuel can reduce production cost, improve the engine's power performance at the same time, but when the methanol percentage is increased (over 2%), the power performance will decrease. With the increase of methanol proportions, the maximum cylinder pressure is slightly increased, the peak of heat-release curves are declined and delayed, the cylinder temperature is decreased, the ignition timings are delayed and the combustion duration is shortened. In addition, NOx emissions were further reduced, but the HC emission, the CO emission and the soot emission has a little rise.

Abstract: A variable-grain strategy is proposed to solve the complicated problem of optimization design on high-speed transmission helical gears with multiple objectives and restrictions. Based on the theory of gear meshing noise and the superiority criteria, a multi-objective evaluation index system is brought forward which gives consideration to the increase of the contact ratio and the decrease of the noise generated by the slide ratio of the tooth flank meshing and the mutation of friction torque, and then the variable-grain multi-objective optimization models of high-speed helical gears are established. The coarse-grained model is utilized in the early design to efficiently determine the direction to the optimal solution. Then the grain is refined and the fine-grained model can be utilized to acquire the optimal result.