Design of Inlet Distortion Generators for Direct-Connect Scramjet Combustors

The paper deals with the design of an aerodynamic device that acts as a facility nozzle and as inlet distortion generator in a direct-connect scramjet combustor test-rig. The device does not only replicate a reference in-flight condition, but also it is also supposed to replicate the dynamic response of the system close to the operating point. This consideration leads to the choice of the inlet cowl section as the reference section for the facility nozzle design. The solution of the design problem is sought by using different approaches of CFD analysis and optimization tools. Numerical simulations based on methods ranging from the method of characteristics to the RANS equations are concerned. The initial design is based on the solution of an inverse problem coupled to optimization by genetic algorithms. The candidate solution are then tested by CFD simulations of the direct-connect facility and the resulting shock reflection patterns are compared to the corresponding patterns computed at the in-flight configurations. The reliability of the design is then evaluated by numerical simulations of the flowfield of the whole direct-connect facility by using a flow solver of the compressible RANS equations. The proposed procedure is checked by designing a nozzle-distortion generator system for a scramjet combustor test-rig model available in the open literature.