Vehicle Variable Turbocharger Turbine Cfd Analysis Of Flow Field

With the increasingly stringent regulations of the engine emission and the increasing scarcity of the energy, energy saving and emission reduction has become the biggest opportunities and the most challenges of the engine today. In order to enhance and improve the power of the engine, economy of the engine and emissions of the engine, the turbocharged engine has become a basic model of the modern engine. For the turbocharged engine, the performance of the turbocharger has an important influence on the performance of the engine, the performance of turbine determine the performance of the turbocharger. The common turbocharged engine has some defects, for instance torque insufficiency at low speed, rev-up response lag and the narrow operating area of low oil consumption. In especial, the common turbocharged gasoline exists engine knock phenomenon. Therefore, variable nozzles turbocharger which has more advantages than common turbocharger becomes a hot research topic of engine researchers.In this paper, the research object is a turbine of one particular variable nozzles supercharger (VNT). The three-dimensional internal flow field of the turbine has been extracted by UG3D drawing software. The three-dimensional steady-state internal flow field of the turbine has been simulated through the computational fluid dynamics (CFD) numerical calculation method, in order to study the motion and change rule of the turbine’s internal flow field. By comparing numerical simulation data and bench test data, the feasibility of numerical calculation of turbine internal flow field can be verified.Research result shows that some results can be obtained through analysing the flow field: the designs of turbine’s volute is reasonable; the flow loss in the volute is small; and it has no bad phenomena such as backflow, rotary flow and sudden expansion and so on. In the inner flow field of the turbine, the distributions of temperature, pressure and velocity accord with the principle of gas dynamics. The flow track of the gas in volute is similar to the logarithmic spiral. At the place of nozzle ring, the flow characteristic of the gas between the blades is entirely consistent with the flow law of the gas in conical nozzle, which is that temperature and pressure are gradually reduced and velocity is gradually increasing along the gas flow direction. However, the head molded line of the nozzle ring blades should be optimized by combining all working condition of the turbine when the opening of nozzle ring become big, in order to reduce the windward block area and the collision loss of blades head. Finally, through the analysis for the flow field of different nozzle ring opening, the working feature of variable turbine can be shown. By changing the nozzle ring opening, the fluid speed entering into impeller is under control, thus the supercharger speed can be controlled to meet the demand of air intake flow in all the engine working conditions.