Evaluation of the grid convergence for a rocket combustion chamber with a porous injector

A study of the grid convergence was carried out in order to quantify the mesh impact on simulations of rocket combustion chambers performed using the averaged Navier-Stokes equations. The present work is a continuation of previous studies on simulations of rocket combustion chambers with the porous injector head API-68. Turbulence is modelled by the SST turbulence model; turbulent combustion is modelled using the extended eddy-dissipation model. The grid convergence study is carried out for two injector configurations (one injector in the middle of the injector head and one injector near the sidewall) on five meshes for each configuration. Results of the work show that the dependences of the flame length and wall heat flux on mesh spacing are described well by a parabola. Using the found dependence on mesh spacing, spatial discretization errors have been evaluated. Analysis of the results shows that a reasonable accuracy of modelling can be reached using the current computational fluid dynamic model at a mesh spacing of around 30 mu m in the flame area.