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Leakage at the piston/cylinder interface of a high-pressure fuel pump for diesel engines becomes more severe due to the increase in delivery pressure. Therefore, a thermal fluid–structure interaction model that can simulate the complex phenomena that take place at the interface is presented in this paper. In the model, the nonisothermal flow, the physical properties of the fluid such as dynamic viscosity and density versus pressure and temperature relationships, the coupled heat transfer between the fluid and structure as well as thermal and pressure-induced elastic deformations of the structure are considered. The calculated leakage rates from the model show good agreement with the experimental results. The impacts of pressure-induced and thermal elastic deformations of the structure on the leakage are discussed. A new direction for reducing the interface leakage is proposed.

In this paper, a nonisothermal fluid-structure interaction mathematical model for the piston/cylinder interface leakage is presented. Full account is taken of the piston eccentricity, elastic deformations of the piston pair, the nonisothermal flow in the interface, and the physical properties of the fluid such as the pressure-viscosity and temperature-viscosity effects. The numerical method for the solution of the model is given, which can simultaneously solve for the fluid pressure distribution and leakage rate in the interface. The model is validated by comparing the calculated leakage rates with the measurements. Results show the good accuracy of the model. The impacts of parameters such as the piston diameter, the initial clearance between the piston pair, and the piston velocity on the leakage rate are discussed. Some of the conclusions provide good guidance for the design of high-pressure fuel pumps.