Numerical Simulation And Analysis Of Flow In Cavity Of High-Pressure Common Rail

High Pressure Common Rail is a new technology for controlling diesel engine emission and still is in development stage in China, so it has the practical significance of studying. Fluid dynamic characteristics of the Common Rail is an important characteristic of the internal combustion engine and has an important effect to the internal combustion engine power performance and fuel economy, which is shown by velocity, temperature and pressure field. Numerical simulation is an intuitive and effective method of researching fluid dynamics. This article uses CFD simulation software FLUENT to study relationship between the cavity of the High-Pressure common rail and the characteristics of flowing.In this paper, the simplify process of the cavity model, the impact of factors and the current researching status of the High-Pressure common-rail is analyzed. And then the operating methods and the basic theories of FLUENT/GAMBIT software is introduced, which is the foundation of modeling and numerical analysis.In this article, GAMBIT2.3 is used to establish various schemes of the cavity High-Pressure common rail and mesh the hexahedral gridding. Firstly, the characteristics of flowing about the three limit cross-section shapes of the cavity is analyzed in numerical analysis of FLUENT and compared to optimum cross-section shape of the common rail cavity. Secondly, the cross-section shape of the cavity is also analyzed and compared to the best cross-section shape of the cavity. Lastly, the fluid characteristics of the schemes of the inlet pressure, volume and small chamfering are respectively analyzed as well as its influence about the fluid characteristics.The results show that, when the largest wall angle of the High-Pressure is within 80 to 90 degree, there is a better fluid characteristic. When the largest wall angle of the model is 84 degree, it has the fluid characteristic of the best. By comparative and analysis of the various scheme, it concludes that the inlet pressure scheme can only change the value without affecting the flow characteristics; Larger volume scheme of common rail can improve pressure-retaining capacity and has a small pressure loss; The small chamfering is beneficial, but the biggest chamfer value must ensure the largest wall angle is within 80 to 90 degree.