Modelling and Exhaust Nozzle Flow Simulations in a Scramjet

Abstract

When pressures and temperatures become so high in supersonic flight that it is no longer efficient to slow the oncoming flow to subsonic speeds for combustion, a scramjet (supersonic combustion ramjet) is used in place of a ramjet. This paper is aimed at modeling the supersonic flow inside Scramjet engine using the Computational Fluid Dynamics ANSYS Fluent. The purpose of this test is to validate FLUENT's ability to predict reflecting shock waves and their effect on wall pressure distribution and heat transfer. Supersonic flow from a nozzle that represents the exhaust nozzle of a supersonic combustion ramjet (SCRAMJET) is modeled. Jet from the nozzle is issued into a domain which is bounded on one side by an afterbody wall which is parallel to the centerline of the nozzle. Shocks propagating from the nozzle exit reflect from the afterbody. Measured values of the distribution of wall pressure and heat transfer rate along the afterbody are used to validate the CFD simulation. In this study, k-ε model has been used to examine supersonic flow in a model scramjet exhaust. The configuration used is similar to the DLR (German Aerospace Center) scramjet model and it is consists of a one-sided divergent channel with wedge-shaped and without wedge shaped. For the purpose of validation, the k-ε results are compared with experimental data for temperature at the bottom wall. In addition, qualitative comparisons are also made between predicted and measured shadowgraph images. The k-ε computations are capable of predicting flow simulations well and good.