In this study, layered double hydroxide (LDH) and molybdenum disulfide (MoS₂) were used as additives to prepare lubricants. The morphology and particle distribution of the LDH and MoS₂ were characterized using a scanning electron microscope and a laser particle size analyzer, respectively. Thermogravimetric analysis was used to compare the performance of the lubricants at high temperature. The extreme pressure and wear resistance performance of the lubricants were tested using a four-ball machine and a fretting-wear machine. Then, the lubricants were applied in a bolt fastener. The loosening torque and surface wear condition at high temperature were compared. By adding LDH and MoS₂ to the lubricants, the extreme pressure and wear resistance performance and anti-seize performance at high temperature were improved significantly. The LDH showed better anti-seize performance than the MoS₂ because of its strong and stable structure at high temperature. The MoS₂ showed better anti-wear performance under a high load because of its soft layered structure. The MoS₂ with a larger particle size showed better extreme pressure performance under a high load. The LDH and MoS₂ played a synergistic effect under the conditions of high temperature and high load.

Three-dimensional flow calculations of the in-cylinder flow for a direct-injection Diesel engine have been carried out with different combustion chambers. In order to assess the decisive factors for the formation and evolution of the in-cylinder flow field, simplified piston bowls were used. A limited number of validation calculations of the compression stroke were performed. The results show that the geometries of the piston have a significant influence on the distribution of the cross section-averaged swirl ratio. The tangential velocity profiles at the cross sections are highly nonlinear, and the rigid body rotation assumption is less admissible. Furthermore, the turbulence in four combustion chambers is analyzed for an insight of the effects of bowl shape, initial swirl ratio and squish. It is found that the squish flow plays a significant role in the turbulence generation process near the top dead center (TDC) during compression. The coupling among the swirl, squish, bowl shape and turbulence is much more pronounced in the combustion chambers.

The oxidation rates of diesel soot from the combustion chamber of a running diesel engine were calculated based on the particle size distributions at different crank angles. The primary particle diameter and nanostructure of soot were obtained by means of high-resolution transmission electron microscopy (HRTEM). The soot characteristics were also investigated by oxidative thermogravimetry and Raman scattering spectrometry. The results showed the soot nanostructures were dependent on engine operation conditions and combustion phases. The oxidation rates were found to differ by nearly fourfold from that calculated by the Nagle/Strickland-Constable (NSC) model for the soots studied here. The varied oxidation rates were interpreted in terms of differences in nanostructure between the soots. The experimental results were used to modify the NSC model and the fringe length of in-cylinder diesel soot was chosen to describe the influence of graphitisation on the oxidation of soot. The modified NSC model lessened the deviation between measurements and predictions.