Overexpanded Two-Dimensional Convergent-Divergent Nozzle Performance, Effects of Three-Dimensional Flow Interactions

Abstract

This paper presents computational results for the  owŽ eld, surface pressure distribution, and internal thrust coefŽ cient of a two-dimensional convergent – divergent nozzle, and compares them with existing experimental results over a range of nozzle pressure ratios (NPRs), including overexpanded conditions. The numerical simulations are based on the implicit solution of the compressible Navier – Stokes equations and the two-equation kturbulence model in conservation law form and general curvilinear coordinates. The solution domain is extended laterally outside the nozzle as well as upstream and downstream of the nozzle exit to simulate the effects of external interactions. Computational results indicate that at overexpanded conditions,  ow entrainment into the nozzle occurs mostly over the  aps, and that a strong secondary  ow traverses the endwalls, behind the shock. Strategies for  ow prediction accuracy and computational efŽ ciency over a wide range of overexpanded NPRs are recommended, based on the assessment of computational results from both three-dimensional and two-dimensional simulations.