Numerical Study On Supersonic Combustion Flow With Unsteady Jet

This paper dealt with the issues of interference between fuel gas jet and main flow in scramjet combustion chamber and the characteristics of unsteady combustion flow field.The numerical simulation of the fuel gas jet supersonic combustion flow field was carried out,and the influence of flow parameters and time effect of fuel gas jet on flow field structure and combustion characteristics of combustion chamber were studied.Firstly,the development of numerical simulation technology on supersonic combustion flow field and the application status of steady fuel injection scheme were summarized.The advantages of unsteady fuel injection scheme to promote fuel mixing and combustion were pointed out.At the same time,the uncertainty of pulse jet flow parameter selection was shown.It indicated the necessity of the research work in this paper.Secondly,the numerical simulation method used in the paper was introduced.The comparison between numerical and experimental results of cold or combustion flow field,based on different physical models,proved the feasibility of numerical method.Then,a basic study was conducted on the supersonic combustion characteristics of the steady transverse jet.The flow field in the direct-connected two-dimensional combustion chamber with wedge/cavity combined structure was studied and analyzed.The influence of wedge structure,static pressure of jet and injection angle of jet on the characteristics of combustion flow field was discussed.There was a clear understanding of the jet interference combustion flow field.Finally,the flow field structure and the combustion characteristics of unsteady pulsed fuel gas jet in the direct-connected two-dimensional combustion chamber with backward-facing step and expansion section was studied and analyzed.The hydrogen mixing amount and hydrogen combustion amount were defined as to analyze the hydrogen mixing and combustion characteristics in the pulse flow field.The determination methods of two kinds of pulsed jet parameters were introduced.The effects of duty cycle and pulse frequency on the characteristics of pulse jet combustion flow field were studied separately.According to the calculation results,suggestions for the pulse fuel injection scheme were given.The work in the paper have a certain guiding significance in the analysis of complex combustion internal flow and the characteristics of fuel gas jet combustion flow field in the scramjet.