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Research On Influence Factors And Suppression Techniques Of Oscillation Combustion In Afterburner

Posted on:2017-01-11Degree:MasterType:Thesis
Country:ChinaCandidate:X LiFull Text:PDF
GTID:2322330509962789Subject:Aerospace Propulsion Theory and Engineering
Abstract/Summary:PDF Full Text Request
The afterburner is easy to bring out self-oscillation combustion which will obstruct normal work and sometime even destroy the structure. It’s very difficult to study the process of oscillation and the internal mechanism in a full size afterburner according to the actual operation Parameters, so that a model afterburner must be put forward. This Paper has designed a model afterburner based on the similarity principle, then studied the influence factors and suppression technique of the oscillation combustion in the model afterburner. Here below are the main works and conclusions in this thesis:Firstly, by calculating the steady numerical simulation of afterburner, the average flow field Parameters can be work out and then designed a model afterburner according to the similarity principle, made a base for the following studies.Secondly, studied the mechanism of oscillation combustion in the model afterburner by numerical simulation and experimental research. Influence factors such as inlet pressure, stoichiometric ratio of fuel-air, nozzle position and flame holder structure were considered. Research indicates that stoichiometric ratio has a significant effect on oscillation combustion, the amplitude of oscillation combustion will increase firstly and decrease secondly as the equivalence ratio increased. Rich fuel air mixture can suppression the oscillation combustion. With the increase of stoichiometric ratio, the frequency of the oscillation combustion will increase slightly, but when the stoichiometric ratio exceeds a certain value, the oscillation mode will change, and so as the frequency. When sustain a certain stoichiometric ratio, the amplitude of the oscillation combustion will increase firstly and decrease secondly as the inlet velocity increase. Different nozzle position will change the length of the mixing section, mixing section distance and inlet gas velocity has an effect on the flow time of air-fuel mixture reaches the flame front. The flow time has a great influence on the phase of heat release rate and pressure pulsation so that the oscillation combustion can be motivated or suppressed.Finally, this thesis has discussed the suppression technique of the oscillation combustion in the model afterburner. The oscillation combustion occurred in the experiment usually has a low-frequency longitudinal oscillation however the perforated plate based on Helmholtz resonance sound absorption principle has very limited results on the low-frequency model. In view of the experiment, the slant radial flame holder can make the flame distribute multi-layer so that a slant flame holder effect is equal to the multi-row ones. It can make the heat pulse frequency of afterburner diversity so that to break the thermo-acoustic coupling, meanwhile to suppress the oscillation combustion.
Keywords/Search Tags:afterburner, oscillation combustion, thermo-acoustic coupling, suppression techniques
PDF Full Text Request
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