Response Calculation Of The Combustion Chamber Structure Vibretion Under The Acoustic Excitation

The combustion chamber is one of the main components of the aircraft gas turbineengine. The actual work condition of the combustion chamber is very poor; the combustionchamber itself not only withstands the mechanical loads caused by the engine work, but alsowithstands the noise loads, temperature loads and aerodynamic loads. The alternating andcontinuing action of these loads easily causes combustion chamber structure acoustic fatigueand thermal fatigue damage, which can seriously affect the life of the combustion chamber,and even the whole aero-engine’s life. Therefore, it is particularly important to study thestructure vibration characteristics under the acoustic excitation, in order to improve the fatiguelife of the combustion chamber.In this paper, based on the finite element method, the vibration problems of the gasturbine engine combustor test rig structure bush segment were analyzed with thecomputational fluid dynamics software FLUENT and finite element software ANSYS. Thetemperature and pressure distribution of the combustion chamber model interior weresimulated with computational fluid dynamics software FLUENT. And regarding the results asthe known conditions of structural analysis, the stress and strain of the structure in the thermalload and pressure load were obtained with the coupling method of ANSYS. In the basis of onthe structure static analysis the structure modal analysis with prestress was performed. It isconsistent that the variation trend of the maximum stress, the maximum strain and the naturalfrequency of the structure with the variation of the structure wall temperature through thecontrast of the structural natural frequency under different conditions. The couplingmechanism of the bush structure and the acoustic field was analyzed, and the structuralvibration characteristics considering the coupling were analyzed as well. The effects of thecombustion chamber acoustic cavity and cooling acoustic cavity on the structure vibrationcharacteristics were further analyzed. Finally, the structure vibration modal test under theacoustic excitation had completed and it made an effective verification to the finite element calculation results. It is found that the finite element calculation results is not far from theexperimental results and enable to meet the requirements of engineering.