Study Of Flow In Volute Of Variable Geometry Turbocharger

With the development of environmental protection in many countries, energy-saving emissions have become the goal of engine industry. The turbocharger has a irreplaceable role in improving engine power, reducing oil consumption and decreasing emissions. However, because of complex structure of the turbocharger volute, it cost a lot of time and labour power to adopt experiment to gain relevant data of volute .So it becomes more economic to simulate turbocharger internal flow field and analysis data using the method of numerical simulate.Through looking up the literature of different turbocharger, this paper makes the performance comparison of different turbocharger, summarizes characteristics of the research object variable geometry turbocharger, analysises the influence of the parameters of flow. Mathematical model is relatively commonly used k -εequation. The turbocharger fluid is three-dimensional viscous fluid.The turbulent flow is calculated by classic SIMPLE algorithm.This paper selects ICEM - CFD and STAR-CD as meshing software and numerical calculation software. Using ICEM - CFD to make the volute meshing with hexahedral grid, tetrahedron grid and hybrid grid and through comparing, we choose hybrid grid. STAR-CD is software using finite volume method of model and it is applied to any shape grid units, therefore numerical calculation use STAR-CD software.After determining the initial and boundary conditions, the flow field of variable geometry turbocharger is simulated, and the distributions of speed and pressure of flow field with different baffle angles are obtained. Calculation results show that, with the baffle angle is between 5°and15°, accelerating effect is better and kinetic energy loss is less, and utilization rate of fuel is improved; when the baffle angle is between 20°and 25°, export speed continues to increase but the distribution has become too uneven which leads to decline of the turbine efficiency. So we should comprehensively consider the influence of the baffle angle of the fluid field.