Research On Acoustic-vibration Coupling Characteristics Of Combustion Chamber In Service

The combustion chamber of aero-engine is in high temperature and high pressure environment under the working condition.The combustion chamber is subjected to complex loads;its failure will result in failure of the turbine,which affects the overall engine performance in turn.The various loads in the combustion chamber do not exist in isolation,and these loads affect vibration characteristics of the structure.The acoustic load generated in the combustion chamber causes the structure to vibrate,and the vibration of the structure causes vibration of the ambient gas,which is the so-called acoustic-vibration coupling phenomenon of the combustion chamber.It is an unavoidable phenomenon under the working condition.In order to reduce the probability of combustion chamber failure and make the design life of the combustion chamber longer,it is necessary to fully study the acoustic-vibration coupling characteristics of the combustion chamber under working conditions.In this paper,by use of the finite element analysis software ANSYS,some simulation technique roadmaps are selected to simulate the model of the aluminum box and the combustion chamber.In particular,the aluminum box model is simulated by acoustic-vibration coupling method in closed and open two states at room temperature;obtain the modal parameters and vibration modes under the acoustic-structure interaction.On this basis,same method is applied to simulating the combustion chamber model in order to obtain the modal parameters and vibration modes of the structure and the gas-fill cavity in closed and open two states under the acoustic-structure interaction.Moreover,the combustion chamber model is simulated by acoustic-acoustic coupling method in the working condition by regulating the mass flow of air and methane,obtaining the modal parameters and vibration modes and conducting harmonic response analysis under the one-way thermal-acoustic-structure interaction.Simultaneously,two modal experiments were carried out at room temperature,which are the aluminum box test and the combustion chamber test in closed and open two states.The response signal was collected by the hammer method and the random excitation method.The random excitation method uses the vibrator and speaker as the excitation source.The data is processed by software M+P SO Analyzer,and the modal parameters and vibration modes of these test systems are identified.The comparison between the experiment modal and the simulation modal shows that the simulation results can approximate the experimental results well,which indicates that the simulation technique roadmaps is effective and conducive to improving the combustion chamber performance.