[Show abstract][Hide abstract] ABSTRACT:
The project presents, preliminary experimental and numerical results on separation of supersonic flow inside a convergent-divergent (CD) contour nozzle. The study is motivated by the flow separation occurring inside CD nozzles operated at low pressure ratio. A novel apparatus allows investigation of many pressure ratios with large optical access and measurement of wall pressures. The separated flow in a convergent-divergent (CD) contour nozzle is investigated by the solution of the Reynolds-Averaged Navier-Stokes equations with a two-equation k-ε turbulent model. For a fixed area ratio, defined as the exit area to the throat area, Ae / At of 1.638, computations are conducted over a range of nozzle pressure ratio (NPR). The computational results are used to further examine the effect of the separated flow. Unlike the experiment, no unsteady shock movements are simulated. The computed wall pressure distribution is in good agreement with the experimental data. Also consistent with experimental observations, the flow separates asymmetrically for the range of 1.5<NPR<3.5 investigated. Further at higher NPR not covered by the experiment, the present computation shows the flow reverts to a symmetric form. Downstream of the shock, flow accelerates to supersonic speed and then recompresses.