Design Method of Scramjet Nozzles within Predetermined Geometrical Space and Experimental Verification

A new design method of scramjet nozzles within predetermined geometrical space is proposed to optimize the nozzle aerodynamic performance. The main characteristic of the proposed method is that the design factors and flow angle are employed to control the nozzle configuration and customize the performance. Firstly, the proposed method and the method of characteristics are introduced. Secondly, the grid resolution is studied, and the proposed method is validated using the computational fluid dynamics (CFD) approach. Then, impact studies are carried out on the design factors and the flow angle in the nozzle design process. The results show that the asymmetry factor has little effect on thrust coefficient, and the lift and pitching moment firstly increase and then decrease with the increase of the asymmetry factor. The thrust coefficient increases firstly and then decreases with the increase of the flow angle, whereas both the lift and the pitching moment present approximately linear increasing trends. After that, the superiority of the proposed method is demonstrated by comparing with the traditional method. The proposed method can improve the thrust coefficient, lift, and pitching moment by 33.94%, 326.42%, and 32.24% at identical design conditions. Finally, a cold flow experiment and the three-dimensional CFD are conducted out to evaluate the effectiveness and accuracy of the proposed method. The experimental results show good agreement with that of numerical simulation. In conclusion, the proposed method not only fully utilizes the geometrical space to increase the aerodynamic performance but also provide further customizability and flexibility in the nozzle design.