This paper reports on a study examining operation of a shockheated secondary driver across the entire operating envelope of a free-piston driven expansion tube. It is found that the secondary driver operating characteristics depend significantly on the specific characteristics of the flow condition. Key trends and characteristics are identified, and theoretical concepts are validated by numerical analysis and experiment.
This paper describes the optimisation and design of a new Mach 12 hypersonic nozzle to be used in the X3 expansion tube. The contoured nozzle has been designed and built to accommodate large-scale models and reproduce constant Mach 12 flows to allow for scramjet testing. The requirements for this nozzle were a core-flow of at least 300mm and exit flow angles below 2°. A new optimisation process has been developed, using a parallel Nelder-Mead method and a new shape has been calculated where CFD analysis indicates the design objectives were successfully met. Off design performance has been evaluated and the nozzle has been shown to retain good core flow size, Mach number and low flow divergence for different inflow conditions.
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