| This work introduces a semi-quantitative schlieren (SQS) method which is used to qualitatively and quantitatively analyze complex, unsteady, compressible flows in a small, planar convergent-divergent nozzle. A basic schlieren system is used to image the evolution in time of complex supersonic flow structures, including Prandtl-Meyer expansion fans, internal shocks, near-wall oblique shocks, quasi-normal shocks, shock/boundary layer interactions, shock/shock interactions, and shock trains. The first images of shock trains in high nozzle-pressure-ratio flows are shown, and the underlying processes are described. A flow-field decomposition method is presented which allows the entire flow field to be separated into unit processes and analyzed. Various methods of analysis are presented, including a new method for the determination of node locations along a defined nozzle wall geometry using the method of characteristics. A numerical solution is developed for the analysis of a blow-down process. Computer programs which implement these solutions are presented. |
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