Variable Geometry Turbocharger (VGT) Flow Field Analysis

With the development of science and technology, turbocharger is undoubtedly one of themost efficient methods to strengthen the internal combustion engine; meanwhile it haspositive effects on reducing pollution, noise and improving fuel economy. Since conventionalturbocharger appears poor torque performance at low speed, lack of fuel economy and the lagin instantaneous response, the variable geometry turbocharger (VGT) can effectively solve theproblems. The paper focuses on one type of variable geometry turbocharger, discussing theapplication of computer aided design(CAD) and computational fluid dynamics(CFD)software on simulating and designing nozzle ring of the variable geometryturbocharger(VGT).The main points of paper are as follows:1. Studying of the basic theory and design optimization method of the researchTurbocharger sensitive parameters of an engine under different working conditions in theimport and export of turbine exhaust pressure, temperature, etc are extracted from theexperiment.2. Using three-dimensional modeling software PRO/E for entity modeling, after thatimport model to ICEM CFD software for dividing meshes and defining boundary.3. In FLUENT software calculates mathematical model by the3-D simulation method ofsteady flow in the simulation and analysis the turbocharger internal flow field includingvelocity, pressure, temperature distribution, through the simulation can reflect in the complexfluid flow of internal turbocharger, and provide flow field basis for nozzle ring design andimprovement.Through simulation analysis of the flow field of the maximum torque point and the ratedpoint can be seen that the gas flow according to fluid dynamics, which show that simulate theflow field of turbocharger by FLUENT is very reliable. But according to the simulationresults, there is flow instabilities at outside of nozzle ring blade which affect turbineefficiency. This research has strong practicability. Setting up of the special nozzle ringcomputer aided design of3-D nozzle ring parametric, providing the criterion of flow field foroptimization design.