Simulation of a Shear Coaxial GO2/GH2 Rocket Injector with DES and LES Using Flamelet Models

HE analysis and design of rocket propulsion systems largely relies on full-scale prototype development and testing. Computational simulation techniques have the potential to assist in the design process if accurate physical models are available. The objective of this study is to address this issues by assessing the predictive capability of three different modeling approaches to simulate the reactive flow field structure of a shear-coaxial rocket injector [1, 2]. To this end, simulations of increasing computational fidelity will be employed, consisting of steady and unsteady Reynolds Averaged Navier-Stokes (U/RANS) calculations, and a large-eddy simulation (LES). For the prediction of the reacting flow field in the rocket injector, a flamelet-based combustion model will be employed [3, 4]. In this formulation, all chemical species, temperature, and thermo-viscous properties are represented by a reduced set of scalars, consisting of the mixture fraction and a reaction progress variable. Effects of turbulence chemistry interaction are incorporated through a presumed PDF formulation. Over recent years, numerous validation studies of rocket injector configurations have been conducted. Most notable is the comprehensive validation effort by Tucker et al. [5]. In this investigation, the GO2/GH2 single element injector configuration by Pal et al. [6] was modeled by different groups. Although this comparison provided valuable insight on wall-heat transfer predictions, it did not allow for an objective quantitative comparison, since all simulations utilized different modeling approaches, turbulence closures, combustion models, and chemical mechanisms. Furthermore, different computational grids were utilized and simulations in two-dimensional and three-dimensional computational domains were performed. The present study attempts to make a more objective comparison among URANS, DES and LES simulations.