Design And Performance Study Of Ramjet Combustor Under Uneven Temperature Condition

The turbine based combined power system used in hypersonic vehicles requires a ramjet combustor to operate stably and reliably over a wide operating range,and requires considering both ejector ramjet rocket mode and ramjet mode.Therefore,the design of flameholder structure and fuel injection mode to ensure flame stability and efficient combustion becomes the most important.Aiming at the flow characteristics and working conditions of the ramjet combustor,a new type of intake-evaporating trailing edge blowing mixture flameholder structure and fuel injection method are designed.Fluent software is used to numerically simulate the non-reaction flow field,the flow characteristics of the stabilizer trailing edge and the two-phase flow combustion in the ramje combustor.Firstly,based on the parameters of combustor working conditions of TBCC rocket ramjet mode design point,using the combination of mainstream annular main flameholder and V-type duty flameholder,five kinds of flameholder structures are designed.After comparing the total pressure loss,the blocking ratio and the inflow rate of evaporative flameholder by numerical calculation,the traditional V-type and intake-evaporating trailing edge blowing mixture flameholder structure are the key research structures.And based on the flow characteristics of the flameholder scheme,the fuel nozzle injection mode and layout method are determined through empirical formulas.The large eddy simulation method is used to investigate the flow characteristics of the trailing edge of the flameholder in non-reaction state,and the wake flow under the traditional V-type flameholder and the intake-evaporating trailing edge blowing mixture flameholder are compared.The results show that intake-evaporating trailing edge blowing mixture flameholder wake flow is more complicated than the V-type structure,which can quickly complete the mixing of the incoming flow and oil flow from trailing edge and the rear baffle gap.And the formed small-scale vortex continuously supplies fresh mixed gas to the recirculation zone,which is beneficial to enhance flame stability and improve combustion efficiency in a high-speed airflow.Finally,considering TBCC convert to ramjet mode,the zonal fuel supply scheme is adopted to realize the advantage of design of flameholder which takes into account both ejector ramjet rocket and ramjet modes.The numerical calculation results of the three-dimensional two-phase flow combustion show that the reaction zone afterⅤ-type and the reaction zone behind the main annual flameholder can be connected through the gap of Ⅴ-type,thus enhancing the flame stability.Under the same working conditions,the recirculation zone of the intake-evaporating trailing edge blowing mixture flameholder is connected to a large,high-temperature zone with a relatively high combustion temperature and uniformity compared to the Ⅴ-type structure.And the combustion performance of the combustion chamber can be improved through more rational fuel distribution.In general,Ⅴ-type flameholder technology is relatively mature at present,compared with Ⅴ-type flameholder combustion,intake-evaporating trailing edge blowing mixture flameholder has more advantages under non-uniform temperature conditions,but its structure is more complex,thus both of them have advantages and disadvantages.