Research On Nonlinear Flow Field Characteristics And Structure Optimization Of Vehicle Turbocharger

Turbocharger is widely used in engine.The exhaust gas turbocharging can not only use the energy of the exhaust gas to increase the intake charge density,improve the engine power,but also have the advantages of improving the thermal efficiency,improving the economy and reducing the noise and reducing the emission pollution.But the working environment of the turbocharger is rather harsh and the impeller is easily subject to fatigue damage.Therefore,it is necessary to accurately understand the internal flow field characteristics of turbine working process,so as to facilitate the improvement of structure,reduce the loss of turbine internal energy and improve turbine efficiency.A large number of studies have shown that the pressure,speed and temperature distribution inside turbocharger turbine have important influence on the performance and efficiency of turbocharger.Reasonable design of the volute and the impeller can evenly distribute the air flow at the outlet of the volute and reduce the flow loss.At the same time,it can reduce the impact of airflow into the impeller and prevent backflow,swirling,sudden expansion and other phenomena.This greatly increases the turbocharger's efficiency.Due to the complex internal structure of the turbocharger,it takes a lot of manpower and time to study the internal flow field using an experimental method.Therefore,the CFD method is used to simulate the internal flow field of the turbocharger turbine in order to understand the flow field characteristics inside the turbine.This paper takes the JP60 S exhaust turbocharger as the research object,and carries out simulation calculation and analysis.First,the mathematical model and theoretical me thod of the turbocharger numerical simulation are determined.Then the transient calcula tion of the turbine geometric model is carried out by Hypermesh software and ANSYS s oftware.The turbine outlet temperature and the internal flow field were obtained throug h simulation calculation.The comparison between the experimental data and the experi mental data shows that the error between the experimental value and the simulated valu e is less than 3.5%.The pressure distribution,temperature distribution and velocity distri bution of turbine are analyzed.By analyzing the distribution of the entropy of the impell er,it can be concluded that the area of high entropy of the impeller is more,and the distr ibution is uneven.This leads to a large loss of energy during operation of the turbine wheel and it is not possible to effectively use the energy in the exhaust gas.Based on the th eoretical basis of impeller improvement,the blade profile of the impeller has been impr oved.The results of simulation again show that the improved overall entropy and high e ntropy area of the impeller is also reduced,and the distribution is even compared with th e original impeller.The temperature at the outlet of the turbine is reduced by 30 K comp ared with the previous time,which means that the improved impeller performs more wo rk than the original impeller,and the turbine efficiency is improved by 6.8%.