Research On Temperature Field Of Turbocharger Tubine Based On Multi-Field Coupling Analysis

Turbocharging, which can drastically improve the performance of internal combustion engine and reduce harmful emissions of automobile, has become high-performance supporting device of diesel engine and gasoline engine. Turbine is main hot end part, for the temperature of engine exhaust gas is high, usually above 873K. And the emission temperature always change along with different operating conditions, such as engine start, stop and standby, so working environment constantly altered between hot and cold has been a big challenge for the turbocharger turbine. Because of that, the crack damage caused by thermal stress is a common failure mode in turbine. For these reasons, study on the temperature field of turbine has great practical value.The paper analyzes the turbine with the methods of weak coupling analysis, which has simplified treatments on the turbine internal flow field, thinks that air flow parameter of the turbocharger's flow part do not change over time, and the pulse phenomenon which caused by turbine and compressor blades and other factors is not taken into account.First, the discretization methods of FE grid on turbocharger turbine and exhaust fluid field as well as the methods of data transmission between different software has been studied. The methods of weak coupling analysis has been used to calculate and analyze the distribution of turbine temperature, and then the effectiveness has been confirmed by comparative analysis. On that bases, stress-strain field of turbine has been got and the maximum stress and deformation has been determined by comprehensive consideration of the temperature load, pneumatic load and centrifugal force effects. At last, using transient analysis method, the temperature trends over time of turbine has been got, then through comparative analysis, the feasibility of the method of solving turbine temperature field has been further verified.By selecting the fluid-structure coupling technique analysis in line with a real physical process on turbine, the results show that the highest temperature is at turbine blade roots, the value is 939K, lower than the initial airflow temperature 27K. Analyzing turbine structure strength, the results show that: the stress concentration appears at the end chamfer of turbine shaft and the root of turbine blades. The maximum equivalent stress value, which is 851MPa, appears at the end chamfer of turbine shaft, while 597 MPa in the pressure surface and 529 MPa in the suction surface at the root of turbine blades. From the strain field of turbine, we can see that turbine blade edge has a more deformations in the radial direction, the value is 1.07mm. And these conclusions have an important significance to guide turbine design.