Experimental study on effects of nozzle layout on response of bluff-body non-premixed flames
Due to the high energy density,inlet velocity and temperature,and uneven mixing of fuel and air,the aero-engine afterburner is prone to combustion instability.The afterburner features a multi-nozzle configuration,where the nozzle arrangement can influence the heat release rate distribution within the combustion chamber,thereby affecting flame response.A model afterburner was taken as the research object to study the heat release rate response characteristics of bluff-body non-premixed flames with different nozzle numbers and nozzle diameters.Acoustic excitation was applied to the flame using two loudspeakers,and the velocity fluctuation was measured using the two-microphone method.Heat release rate fluctuation was measured using a photomultiplier tube combined with the CH*filter.The experimental results show that the change of nozzle layout has a significant effect on the heat release distribution within the combustion chamber.The flame transfer function(FTF)gain shows a typical double-peak feature.As the number of nozzles increases,the peak gain initially decreases and then increases.The frequency corresponding to the peak has a tendency to move to a high frequency.However,the system time delay remains largely unchanged.With the increase of nozzle diameter,the FTF gain initially decreases and then increases,while the system time delay increases.
aero-engineafterburnercombustion instabilitybluff-body flame stabilizernozzle layoutflame responseflame transfer function
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