Study On Oil-Air Distribution And Combustion Performance Of High Oil-Air Ratio Combustor

In order to meet the demand for high thrust-to-weight ratio of the new generation of military aeroengines,it is necessary to continue to increase the fuel-air ratio and temperature rise capability of the combustor.The traditional combustion organization method will bring about problems such as reduced combustion efficiency and poor outlet temperature distribution under high oil-gas ratio conditions.The central staged combustion technology has the potential to solve the above problems and has become a current research hotspot.In this paper,the effects of structural parameters of cyclone and main stage injection on fuel distribution and combustion performance of a high fuel-air ratio model combustor with central stage combustion technology are studied by numerical simulation.The main conclusions the current study arrive at are as follows:(1)Under the design conditions,the effects of the length of the convergent section of the flame tube and the swirling combination,the blade angle and the radial height of the two-stage swirler on the air flow field,fuel concentration field and the resistance loss of the combustor are studied.The research results show that when the length of the convergent section of the flame tube is 80 mm,the two-stage cyclones are in the same direction,the blade angles are 32° and 60°,and the radial height is 23 mm,a cold flow field with more uniform fuel-air mixing and lower resistance loss can be obtained.(2)Taking the main combustion stage coaxial downstream air atomization single nozzle as the research object,the influence of the nozzle fuel flow,the auxiliary air flow,the ambient backpressure and the swirl conditions on spray characteristics such as spray penetration depth and particle size distribution is analyzed.The research results show that when reducing the nozzle fuel flow,increasing the auxiliary air flow,increasing the environmental back pressure and adding the swirling flow,the average Sautel diameter in the whole field can be reduced and the droplet size distribution can be more uniform.(3)Based on the atomization characteristics of the single nozzle,the effects of the number of nozzles,the injection angle,the nozzle gas-liquid ratio of the main fuel stage and the two-stage fuel grading ratio on the fuel distribution characteristics and combustion performance of the combustor are studied.The research results show that when the number of nozzles is 10,the injection angle is 15°,the nozzle gas-liquid ratio is 0.25,and the higher fuel ratio of the main combustion stage,the uniformity of the fuel-air mixing can be improved and the combustion performance can be better.