Abstract
Multi-element thrusters operating with gaseous oxygen (GOX) and methane (GCH4) have been numerically studied and the results were compared to test data from the Technical University of Munich (TUM). A 3D Reynolds Averaged Navier–Stokes Equations (RANS) approach using a 60° sector as a simulation domain was used for the studies. The primary goals were to examine the effect of the turbulent Prandtl number approximations including local algebraic approaches and to study the influence of radiative heat transfer (RHT). Additionally, the dependence of the results on turbulence modeling was studied. Finally, an adiabatic flamelet approach was compared to an Eddy-Dissipation approach by applying an enhanced global reaction scheme. The normalized and absolute pressures, the integral and segment averaged heat flux were taken as an experimental reference. The results of the different modeling approaches were discussed, and the best performing models were chosen. It was found that compared to other discussed approaches, the BaseLine Explicit Algebraic Reynolds Stress Model (BSL EARSM) provided more physical behavior in terms of mixing, and the adiabatic flamelet was more relevant for combustion. The effect of thermal radiation on the wall heat flux (WHF) was high and was strongly affected by spectral models and wall thermal emissivity. The obtained results showed good agreement with the experimental data, having a small underestimation for pressures of around 2.9% and a good representation of the integral wall heat flux.
Highlights
The design and optimization of rocket propulsion devices is a complex procedure that nowadays includes the numerical simulation of flow and tough physical phenomena as a very important part of the process
It is likely that the underestimation of heat flux (HF) is either due to unconsidered radiative heat transfer which would contribute into the total amount of heat flux, or poor performance of the turbulence model, which is discussed later
As the library used in the flamelet approach accounts for many reactions compared to the eddy dissipation model (EDM) approach and is more robust and showed better results for absolute pressures in this case, it was proposed for further use among these two
Summary
The design and optimization of rocket propulsion devices is a complex procedure that nowadays includes the numerical simulation of flow and tough physical phenomena as a very important part of the process. Some numerical studies have already been made to examine the effect of modeling approaches using both a single-injector test case [3,4,5] and a multi-element setting [6,7,8,9]. In our paper, the cheapest and most robust techniques were tested to establish a modeling methodology of such complex phenomena applicable for industrial applications and purposes Such industry demands drive the usage of most universal approaches for any processes described by the computational model, as changes in the geometry and mass flows during the optimization might change the parameter field significantly. The experimentally determined data included heat flux for each segment, mean pressure, wall wall pressure distribution, wall temperatures, and methane/oxygen flow rates.
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