Due to the high speed and high temperature of engine exhaust, the turbocharger bears very high heat load. The heat dissipation of turbocharger is an important factor to determine the service life and performance of turbocharger. In this paper, a mathematical model of the fluid-structure interaction heat transfer of the water-cooled bearing body of turbocharger was established and the cooling performance of a 1.8 L gasoline engine turbocharger was analyzed. The effects of cooling water inlet flow, engine exhaust temperature, cooling water inlet temperature, and wall roughness of cooling water chamber on the cooling performance of important parts of the bearing body were analyzed by the numerical simulation method. In addition, the cooling water flow required by bearing body with a different structure under different working conditions was studied based on the orthogonal test method. The predicted result shows a good agreement with the experiment result, which could provide a reference for relevant production design and cooling strategy. In the range larger than the thickness of laminar flow bottom layer of the cooling water chamber wall, the increase of wall roughness height can enhance the heat transfer between the fluid and the solid.

In order to investigate the distribution characteristics of gas-particle two-phase flow in the diesel particulate filter in the capture process, a mathematical model of gas-particle two-phase flow for inside-and-outside filter had been established in the capture process according to the mass conservation equation, momentum conservation equation, and k-ε turbulence equation. The model verification was carried out with the experimental and simulated of flow distribution characteristics of gas-particle two-phase. The obtained results showed that the static pressure gradient along the radial distribution was greater at the inlet of the filter in capture process in the diesel particulate filter, which could easily lead to causing eventual fatigue damage due to stress concentration in the front-end of filter; moreover, the weaker the vortex strength of gas-particle formed in expansion pipe was, the better uniformity of flow velocity and soot concentration distribution were. Therefore, the established mathematical model can be used for predicting gas-particle flow velocity distribution in the diesel particulate filter.