Parametric Modeling And Active Control Technology Of Combustion Oscillation

In order to reduce nitrogen oxide emissions and achieve higher combustion efficiency,modern aero-engine combustors are increasingly using lean premixed combustion.However,lean premixed combustion is more prone to oscillations,accompanied by large fluctuations in heat release and pressure,which degrades combustion performance and reduces the life.In this paper,the combustion engine oscillation problem is built,the one-dimensional parametric model of the combustion chamber is constructed,and the related active control algorithm is studied.(1)Combustion oscillation modeling of the combustion chamber.In order to simplify the modeling process,this paper models the one-dimensional annular combustion chamber.In order to study the coupling relationship between acoustic waves and fuel heat release,the relationship between the average thermodynamic parameters such as velocity,temperature and pressure before and after ignition in the combustion chamber is first established by conservation equations.Then relationship between the heat release rate and gas velocity is expressed by the flame model.Finally the complete combustion chamber thermoacoustic coupling dynamics model is constructed in combination with the boundary conditions.(2)Perform frequency and time domain analysis of the combustion model.The frequency domain analysis is used to study the oscillation frequency of the main mode of combustion oscillation,and the variation law of the oscillation frequency under different gas perturbation speeds.Time domain analysis studies the law of gas velocity and pressure as a function of time,as well as the saturation characteristics of gas velocity and pressure oscillation in a non-linear combustion state.Finally,the influence of combustion chamber geometry parameters,inlet airflow parameters and boundary conditions on the oscillation mode is analyzed.(3)Research on active control algorithm of combustion oscillation.Construct a phase delay controller and an H H_? loop shaping controller.Both controllers use the feedback of the heat release rate to control the combustion oscillation with the speaker as the actuator,which has better oscillation suppression effect,and the H_? controller is suitable for wider working conditions.(4)Perform combustion oscillation and its active control test to verify the effectiveness of the combustion model and controller.The combustion test platform uses propane as a fuel to achieve lean combustion conditions and stimulate combustion oscillation.It has achieved good results in the active combustion control test,and the speaker can be used as an actuator to suppress the oscillation amplitude by 24.6 dB.