Overexpanded Two-Dimensional-Convergent-Divergent Nozzle Flow Simulations, Assessment of Turbulence Models

Abstract

HERE is renewed interest in two-dimensional‐ convergent-divergent (2D‐CD) nozzles because of the advantages they offer over axisymmetric cone gurations for supersonic transport. These include higher performance, reduced afterbody drag, easier integration with airframes, and large mechanical area excursion capabilities. The performance of these nozzles can suffer at off-design conditions when the large nozzle area ratio reductions required during subsonic and transonic acceleration cannot be achieved under the mechanical and control system constraints. Because this can adversely affect the acceleration time to cruise, the fuel burnt, and the range, it is desirable to predict off-design performance with a high degree of accuracy. The purpose of the present investigation is to assess the computational results obtained for overexpanded 2D‐ CD nozzles using e ve different turbulence models. Overexpanded nozzle e ow predictions are challenging because of the large shock-induced separated e ow regions in the divergent nozzle section. The 2D‐ CD nozzle tested under static conditions by Hunter 1 was selected for the numerical assessment because the large number of pressure taps gave a better dee nition of the shock location. The nozzle has a design pressure ratio of 8.8 for an exit Mach number of 2.1. Approach The implicit numerical solution of the compressible twodimensional Navier‐ Stokes equations was obtained using the NPARC code.