Modeling And Application Of Scramjet Engine Based On One-Dimensional Euler Equations

The world's major aerospace powers attach great importance to the research of the air-breathing hypersonic vehicle,with its outstanding strategic significance.The vehicles also promise to be among the greatest technological challenges such as the scramjet technology and airframe/propulsion integration analysis.The rapid assessment of scramjet performance and design analysis of integrated model deeply rely on the efficient quasi-one-dimensional scramjets numerical model and the computational method for internal/external coupled flowfield of hypersonic vehicle/scramjet.This paper has carried out the following work based on these requirements.First,the finite-rate reaction model was introduced into the quasi-one-dimensional Euler equations with adding the source terms for the cross-sectional area variation,fuel addition and wall friction to solve the chemical non-equilibrium internal flow of scramjet.The Strang's operator splitting method was used to split chemical non-equilibrium flow into flow part and reacting part to resolve the numerical stiff problem induced by the chemical non-equilibrium.The dual time step approach based on “source eliminating method” were presented for calculating the flow part and ?-QSS algorithm for calculating the reacting part.One-dimensional numerical investigations of different scramjet models were carried out,and the results indicated that the accuracy and effectiveness of the two models are validated by good agreement with the experimental data.Furthermore,the one-dimensional characteristics of combustion flow field of the NAL scramjet under different hydrogen equivalence ratios and inlet pressures were also calculated.For the research of the airframe/propulsion integrated model,the data transfer between the internal and external flow field interface and the coupling iteration process was realized with Fluent UDF programming,and the coupling method of two-dimensional external flow of hypersonic vehicle and quasi-one-dimensional internal flow of scramjet was established.The numerical simulation of the coupling flow conditions for a typical integrated hypersonic vehicle configuration under cold flow and ignition condition indicated that the calculation results were reasonable agree with the real physical law.Meanwhile,the method can also provide the characteristics of the external flow field,the chemical non-equilibrium engine flow and the true coupling effect of the full flowfield.The related work in this paper can provide an important reference for the performance analysis of scramjet and the design of the aircraft/propulsion integration model.