A turbulence model study of separated 3D jet/afterbody flow

Abstract

Three-dimensional RANS calculations and comparisons with experimental data are presented for subsonic and transonic flow past a nonaxisymmetric (rectangular) nozzle/afterbody typical of those found in fast-jet aircraft. The full details of the geometry have been modelled, and the flow domain includes the internal nozzle flow and the jet exhaust plume. The calculations relate to two free-stream Mach numbers of 0⋅6 and 0⋅94 and have been performed during the course of a collaborative research programme involving a number of UK universities and industrial organisations. The close interaction between partners contributed greatly to the elimination of computational inconsistencies and to rational decisions on common grids and boundary conditions, based on a range of preliminary computations. The turbulence models used in the study include linear and nonlinear eddy-viscosity models. For the lower Mach number case, the flow remains attached and all of the turbulence models yield satisfactory pressure predictions. However, for the higher Mach number, the flow over the afterbody is massively separated, and the effect of turbulence model performance is pronounced. It is observed that non-linear eddy-viscosity modelling provides improved shock capturing and demonstrates significant turbulence anisotropy. Among the linear eddy-viscosity models, the SST model predicts the best surface pressure distributions. The standard k − ε model gives reasonable results, but returns a shock location which is too far downstream and displays a delayed recovery. The flow field inside

Double skin façade: Modelling technique and influence of venetian blinds on the airflow and heat transfer

“…From numerical analysis point of view, the accuracy of computations is affected by the choice of grids, the viscous models, discretisation schemes and convergence and had been the major concern for numerical scientists [16][17][18]. These uncertainties that may influence the flow physics were carefully taken into account in the numerical modelling for greater accuracy.…”

Interaction Effects Between Surface Radiation and Double-Diffusive Turbulent Natural Convection in an Enclosed Cavity Filled With Solid Obstacles

“…While treating the flow to be laminar is rather unambiguous at least from the viewpoint of viscous models, this is not so for turbulent flows. It is well known [Hasan 2004, Wang 2004] that turbulence models play an important role in the predictions of fluid flows. Hence we first checked the turbulence model sensitivity and later made further comparison to validate our justification for the approach.…”

“…From numerical analysis point of view, the accuracy of computations is affected by the choice of grids, the viscous models, discretisation schemes and convergence and had been the major concern for numerical scientists [Chen and Liu 2004, Hasan et al 2004and Wang and Mujumdar 2004. These uncertainties that may influence the flow physics were carefully taken into account in the numerical modelling for greater accuracy.…”

Geometry Parameterisation and Aerodynamic Characteristics of Axisymmetric Afterbodies

“…The pressure readings are integrated to obtain pressure forces that are used to compute the pressure drag coefficient CDβ [2], [4], [9], [11]. There also have been previous computational studies on afterbody and nozzle system aerodynamic performance [12]- [14]. This data was mostly used to validate numerical schemes or as a case study and it was restricted to specific areas such as internal exhaust performance.…”