Three-dimensional simulation of combustion instability characteristics in LPP combustor
In order to analyze the combustion instability(CI)characteristics of lean premixed pre-vaporized(LPP)combustor,three-dimensional Helmholtz equations were simplified at three different levels.The average temperature field equation without source term,the imported CFD temperature field equation without source term,and the imported combustion flow field characteristics equation with source term,were respectively simulated for the single-head LPP combustor model in three-dimensional frequency domain.The results showed that the temperature distribution in the combustor was an important factor affecting the acoustic eigenfrequency of the combustor,and the source term of heat release rate had no effect on the main frequency.Compared with only setting of average temperature field,importing the 3D temperature field calculated by CFD can obtain more consistent results with the experimental frequency,and the accuracy was increased by 5％.The relationship between the acoustic system and the combustion flow field can be quickly established by solving the frequency domain equation in a decoupling way.The spatial distribution characteristics of heat release rate and hysteresis time were represented by the source term of the Helmholtz equation,which had no effect on the prediction of the natural frequency of the combustion chamber,but the detailed sound pressure distribution characteristics can be obtained.
lean premixed pre-vaporized(LPP)combustoracoustic eigenfrequencycombustion instability(CI)finite element calculationthermal acoustic coupling
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