Influence of the Facility Nozzle Design in the Unsteady Response of Direct-Connect Scramjet Combustors

A numerical approach to the automatic design has been applied to the aerodynamic design of a device that acts as a facility nozzle and inlet distortion generator for a direct-connect scramjet combustor test-rig. The technique combines GA optimization and an inverse method based on a lightweight MoC solver for an efficient search of non-local extrema. The solution of the design problem is sought by using different approaches of CFD analysis and optimization tools. The initial design is based on the solution of an inverse problem coupled to optimization by genetic algorithms. The result of the optimization is then tested by CFD simulations of the direct-connect facility and the shock reflection patterns are compared with those of the in-flight configuration. The verification of nozzle design and the assessment of the prescribed flow distortion are then carried out by numerical simulations of the flowfield of the whole direct-connect facility by an URANS solver. Global effects of combustion dynamics have been included by using an heat-release model. The proposed procedure is checked by designing a facility nozzle and distortion generator system for a scramjet model available in the open literature.