Investigation On The Structure And Performances Of Chevron Mixer For The Afterburner

As a important part of military turbofan engine, the afterburner supplied a maximum thrust in ashort time to satisfy some special flight condition like take-off and speedup. Supplying a symmetricalinlet flow field and optimizing the combustion were the key to enhance the performances of theafterburner. In this paper, a turbofan engine afterburner with chevron mixer was simulated byreasonable Viscous Model, Combustion Model and Discrete Phase Model. The three-dimensionalflow fields and combustion characteristics of the afterburner were computed to improve theperformance of the chevron mixer and the fuel distributing of the afterburner.The afterburners with different chevron mixers were simulated by k-ε Viscous Model. Theconfiguration parameters of chevron mixers included the length(L), number(n) and inscribed angle(α)of the sawtooth. Analysis was done to find the relation between the chevron mixers configurationparameters and the afterburner aerodynamics characteristics such as stream-wise vortices structures,thermal mixing efficiency, the inlet temperature of the flame stabilizer and the total pressurerecovery coefficient, ect. The research showed that increaseing the length(L) and angle(α) of thesawtooth could improve the performance of the chevron mixer, but the increasing of inscribednumber(n) which restricted the development of stream-wise vortices has disadvantages of the mixingenhancement. In general, when L=82.75mm, n=24, α=40o, the configuration of the mixer was a goodchoice.Based on the three-dimensional flow field simulation of the afterburner, Combustion Model andDiscrete Phase Model were added into the simulation. The afternuer was divided into five oil supplyareas. The mass flow of the fuel were adjusted to analyze the influence of afterburner combustioncharacteristics which included afterburner wall temperature, afterburner inner temperature,combustion efficiency, fuel concentration and fuel particle diameter, ect. The research result showedthat decreasing the oil mass flow in2and3oil supply area not only could lower the wall temperature,but also could reduce the radial temperature gradient. The combustion efficiency could be improved0.92%.