Research On Contour Design And Flow Control Of Single Expansion Ramp Nozzle

At present, hypersonic vehicle and its propulsion system are investigated and developed by many countries. From the view of integration of airframe and propulsion system, the single expansion ramp nozzle with large expansion ratio is the most reasonable exhaust system. The study of contours design and flow control on this type of nozzle is carried out based on method of characteristics and CFD in this thesis.Firstly, the divergent section is designed using method of characteristics and corrected considering the thickness of boundary layer. The convergent section and transition section are designed via formula of Vizinski and equation of super-ellipse. The design of single expansion ramp nozzle is completed after assembling the divergent section, the convergent section and the transition section.Secondly, the numerical simulation of flow for nozzle designed is conducted on design point and along flight trajectory, Parameters of performance under different flight state is computed to investigate the change of nozzle performance. To improve the off-design performance, the effect of changes in geometry parameters on flow field and performance of nozzle is investigated and the scheme of geometry adjustment is presented.Finally, the secondary flow injection is shown to improve the over-expanded performance of single expansion ramp nozzle. The 2D and 3D flow field of nozzle with secondary flow injection is numerically simulated to study the effect of mass flow of secondary injection, total pressure of secondary injection, angle of secondary injection, location of secondary injection, shape of secondary injection orifice and Mach of free stream on over-expanded performance of nozzle. The results show that improvement of performance has been achieved by secondary flow injection on the lower flap. The configuration of flow field presented in this thesis is similar to the typical interaction flow field. The effect of secondary flow injection on nozzle decreases with the increase of nozzle pressure ratio. Mass flow and angle of injection which have optimum values are important factor while total pressure of injection and...