Study On Rotating Detonation Combustion Characteristics Of Methane Reforming Gas

Rotating detonation combustion engine has become one of the hot research fields of detonation combustion due to its advantages of simple structure,fast combustion rate and continuous operation of single detonation.The flow field of methane reforming gas/air rotating detonation combustion is numerically simulated in this paper.The model design of rotating detonation chamber was carried out.On this basis,the typical flow field of rotating detonation is studied,and the outlet parameters of rotating detonation chamber are estimated,and the turbine guide vane is designed according to the estimated results.In order to study the influence of different fuel components on the flow field of rotating detonation combustion,numerical simulation of rotating detonation chamber without guide vane and rotating detonation chamber with guide vane was carried out respectively.Specific work contents are as follows:(1)According to the inlet conditions of the micro gas turbine combustion chamber,the design work of the methane reforming gas rotating detonation chamber is carried out under the conditions of total inlet pressure of 0.3MPa,total temperature of 409K and equivalent ratio of 1.According to Bykovskii’s empirical formula,the combustion chamber is designed.The flow field structure of rotating detonation combustion under the combustion chamber was analyzed,and the exit parameter of the simulation result was taken as the inlet parameter of the turbine guide vane to design the guide vane shape.According to the design result,the coupling was carried out with the combustion chamber mentioned above.(2)The influence of the components of methane reforming gas on the characteristics of rotating detonation combustion was studied.The propagation process of rotating detonation wave of methane reforming gas was studied by using methane reforming gas with different methane conversion rates as fuel and air as oxidant.Under different components,five propagation modes are obtained,which are single-wave mode,single wave with counterrotating components mode,two-wave mode,three-wave mode and four-wave mode.With the increase of methane conversion,a multi-wave mode appears in the combustion chamber,and the number of detonation waves increases with the increase of methane conversion.With the increase of methane conversion,the velocity and pressure of detonation wave decrease gradually.The combustor booster ratio decreases with the increase of methane conversion,and the uniformity of total outlet pressure and total temperature decreases with the increase of methane conversion.(3)The influence of multi-component fuel on the combined working characteristics of rotating detonation combustion and turbine components is studied.The working process of the coupling between the rotating detonation combustion chamber and the turbine guide vane is numerically simulated.Considering the influences of different fuel activities on the coupling,the flow field structure of the rotating detonation combustion chamber and the working characteristics of the turbine guide vane are analyzed.With the increase of fuel activity,the propagation mode changes from single wave mode to unstable single wave mode.After oblique shock waves sweep through the turbine guide blades,the flow field structure near the guide blades changes,and boundary layer separation occurs at the trailing edge of the turbine guide blades,which is aggravated by unstable single-wave modes.With the increase of fuel activity,turbine guide vane pressure loss gradually increases.The total pressure loss coefficient of single-wave mode is 9%,and the total pressure loss coefficient of unstable single-wave mode is 4%-6%higher than that of single-wave mode.The turbine guide vane has a certain inhibition effect on the pressure oscillation at the outlet of the combustion chamber,and the disturbance generated by detonation wave extinguishing in the unstable single-wave mode will be transmitted to the outlet of the guide vane.