Characterization of GO2–GH2 Simulations of a Miniature Vortex Combustion Cold-Wall Chamber

This study describes a numerical simulation of a miniature vortex combustion cold-wall chamber using a two-stage choked nozzle approach. Recognizing that the nozzle is choked at the throat under normal operation, the miniaturized vortex chamber is decomposed into two parts: The first segment extends from the headwall to the throat, whereas the second extends from the throat to the nozzle exit plane. In stage 1, an incompressible model is used leading up to the nozzle entrance. In stage 2, compressibility is superimposed, starting with the output from stage 1. This two-stage simulation reduces CPU time and helps to achieve convergence. Compressible simulations are then performed using a three-dimensional pressure-based, finite volume, unstructured solver. Furthermore, reaction mechanisms are simulated using a non-premixed combustion model with adiabatic probability density function lookup tables. Eight conventional chemical species are used, including O2, H2, H2O, HO2, H2O2, O, H, and OH. At the outset, the existence of a bidirectional motion is demonstrated and the spatial invariance of the so-called mantle interface, which separates inner and outer vortex regions, is corroborated. This work confirms the effectiveness of convective film cooling of the chamber walls as a characteristic feature of cyclonic motion involving a low-temperature oxidizer.