Influence of spatial discretization and unsteadiness on the simulation of rocket combustors

Summary This paper investigates some important numerical aspects for the simulation of model rocket combustors. Precisely, (1) a new high‐order discretization technique (multi‐dimensional limiting process (MLP), low diffusion, and MLPld) is presented and compared with conventional second‐order schemes with different flux limiters. (2) Time accurate unsteady Reynolds‐averaged Navier–Stokes (RANS) simulations are performed to assess possible improvements in comparison with steady‐state RANS simulations. (3) Fully 3D simulations of an axisymmetric rocket combustor are compared with 2D axisymmetric ones. All studies are based on the Penn State preburner combustor experiment, which uses gaseous oxygen and hydrogen. This comprehensive study offers unique insight into how the mentioned numerical influence factors change the flow field, flame, and wall heat fluxes in the model rocket combustor. Because wall heat fluxes are known from the experiment only, numerical results are compared with LES of other authors, too. It will be shown that the high‐order spatial discretization significantly improves the agreement with measured wall heat fluxes at low additional computational cost. In general the transition from simple to more complex numerical approaches steadily improves the qualitative agreement between simulation and experiment. Copyright © 2015 John Wiley & Sons, Ltd. A new high order discretization technique (MLPld multi‐dimensional limiting process, low diffusion) is presented and compared to conventional second order schemes with different flux limiters. Time accurate URANS (unsteady RANS) simulations (two‐ and three‐dimensional) of an axisymmetric rocket combustor are performed to assess possible improvements in comparison to steady‐state RANS (Reynolds‐averaged Navier‐Stokes) simulations. The high order spatial discretization significantly improves the agreement with measured wall heat fluxes at low additional computational cost.