Application Of Turbulence Models For Aero-engine Combustor Numerical Calculation

Nowadays with the development of the aviation industry, as the heart of the aircraft, the technology of engine is one of the most important factors to determine the level of performance of the aircraft. Currently the main bottleneck to restrict China's large aircraft project is the lack of development of high-performance engine corresponding. The combustion chamber is one of the core parts of the engine, it has a great impact on engines' life and reliability. Therefore, the analysis of the engine's combustion chamber is particularly important.Before numerical simulation, firstly, compare the turbulence models which are widely used nowadays, which includes the standard ?-? model, the RNG ?-? model, the realizable ?-? model and the large eddy simulation model, which was raised in recent years.Especially compare their advantages and disadvantages as well as the scope of application.Then use these four models to get a numerical simulation for the aero-engine combustion chamber respectively, then get the results of flow field under each model. And with the help of realizable ?-? model, one can get a deep exploration about the combustion characteristics of this type engine combustion chamber.The basic function of aircraft engine chamber is, in a very bad condition, to organize efficient combustion process and change the jet fuel chemical energy into heat energy. The flame tube is one of the main organization combustion units in the combustion chamber, and the combustion process takes place in the flame tube wall. In the process of combustion, the temperature in the main combustion zone will reach at as high as more than 2000 K, in this temperature range, basically all the metals or alloys have been melting. Therefore, in order to protect the combustion chamber components, it should take measures to cool the flame tube effectively. To achieve this goal, when designs the combustion chamber, people adds one structure named cooling hole. Cooling hole is mainly used for the entrance of the cooling air,the cooling air will mix with the hot gas in the combustion chamber, through this it can reduce the hot gas temperature, and this will actually protect the combustion chamber components.The distribution and the size of the cooling hole will affect the combustion process, in order to study the effect of cooling hole size for the combustion process, select three different size of cooling hole and analyze their combustion results. Firstly, according to the size of a real aircraft engine, I have built a model related to the combustion chamber, and then divided the grid. And then in the FLUENT software, select some turbulence models which are widelyused nowadays as a calculation example. This includes the standard ?-? model, the RNG?-? model, the realizable ?-? model and the large eddy simulation model, which was raised in recent years. Compared and analyzed the combustion results, and then select the compare suitable turbulence model to apply in this engine combustion chamber. Finally, using the chosen turbulence model for the five different sizes of cooling hole, to analyze their combustion characteristic. At the same time, in order to examine the engine more clearly,study the combustion under different fuel injection quantity and air amount, and according to the combustion results, put forward some advice to the design of the combustion chamber.