In the recent years, the present research group contributed with success to the research and development initiatives promoted by the Italian Space Agency (ASI), the European Space Agency (ESA), and AVIO spa, devoting extensive efforts to modeling and simulating combustion phenomena and heat transfer in liquid rocket engines.
We propose to improve the computational capabilities of the present research group to extend the range of applicability of our numerical CFD models. This project's objective is to construct the numerical tools to predict the combustion and heat transfer phenomena in a throttleable, pintle injector-based, Oxygen-Methane
Liquid Rocket Engines (LRE) thrust chamber. To ensure the translational impact of the numerical tools, we propose to account for the uncertainties of the implemented models by resorting to efficient uncertainty quantification (UQ) techniques, measuring the degree of belief that a designer should have on the numerical estimates.
The project proposed here would guarantee the research group, and therefore Sapienza University, to maintain its leadership position in the space propulsion field.
This project aims to construct an efficient simulation toolkit to analyze the combustion in a throttleable, pintle injector-based, Oxygen-Methane Liquid Rocket Engines (LRE) combustion chamber.
This technological asset is still missing in the current national research scenario and is of paramount importance for the design process of new rocket engines. A long-term impact of this line of research is to reduce the costs of rocket engine development.
A strong effort of the scientific community has been devoted to specific aspects of combustion in LRE chambers. The experimental effort on supercritical combustion in the past two decades has been focused on coaxial flows at high pressures, representative of actual rocket engine conditions. Most of the existing studies have been focused on the liquid oxygen and gaseous hydrogen mixtures, investigating supercritical combustion at pressures up to 100bar [1]. The high-pressure combustion of LOX and methane were only recently investigated [2], showing that the flow and structures formed in the doubly trans-critical injection configuration can strongly differ from that where only LOx is injected in a trans-critical state.
A unified treatment of fundamental multi-species thermodynamics is commonly employed since the pioneering works of V.Yang group [3]. Supercritical combustion simulations using both LES and DNS were performed in two dimensions [4]. The near field flame dynamics of a LOX/methane shear-coaxial injector using LES without any turbulent combustion model and a global chemical mechanism was studied in [5].
A fully three dimensional LES of a cryogenic flame was performed using a simplified infinitely fast flamelet method [7]. We propose to employ a finite-rate chemistry approach, and to rely on the research group expertise in detailed mechanisms reduction [12,13], to generate cost-effective skeletal mechanisms from the original detailed ones.
The heat transfer in the combustion chamber (i.e., heat conduction in the chamber wall and coolant flow in the regenerative circuit) can be handled by using RANS approaches [8]. Only recently, a few efforts have been made which consider more refined modeling approaches, such as LES or DNS [9].
However, these studies are still far from the applications of interest. In fact, to properly verify the design of a rocket engine combustion chamber, the analysis tools must be capable to cope with turbulent flows within complex geometries, reactive mixtures under supercritical pressure conditions, and conjugate heat transfer. While such a class of numerical solver is still missing in the open literature, some efforts in this direction are made by CERFACS (France) AVBP [10] using a high-fidelity LES approach, and by Airbus Space and Defence Group (Germany) resorting to RANS approach.
Finally, the effects of pintle injector geometry on combustion in a liquid oxygen/liquid methane rocket engine were experimentally inquired by Haidn's group at DLR [11].
The numerical solvers developed by the present research group have permitted, on the one hand, to contribute with success to the research and development programs cited in the previous sections, namely, ISP-1, LYRA, HYPROB programs, and the collaboration with AVIO. On the other hand, to progress with the basic comprehension of the turbulent heat transfer to supercritical fluids, with particular regards to methane.
The project proposed here guarantees the research group, and therefore Sapienza University, to maintain its leadership position in the space propulsion field.
Bibliografy
[1] W. Mayer & H. Tamura J. Propul. Power 12 (1997) 1137-1147.
[2] G. Singla et al. Proc. Combust. Inst. 30 (2005) 2921-2928.
[3] V. Yang Proc. Combust. Inst. 28 (2000) 925-42.
[4] J. C. Oefelein Proc. Combust. Inst. 30 (2005) 2929-2937.
[5] N. Zong & V. Yang Proc. Combust. Inst. 31 (2007) 2309-2317.
[6] T. Kim et al. J. Supercrit. Fluids 81 (2013) 164-174.
[7] T. Schmitt et al. Proc. Combust. Inst. 33 (2011) 1383-1390.
[8] L. Wang et al., Appl. Therm. Eng. 54 (2013) 237-246
[9] G. Ribert et al., Comput. Fluids 117 (2015) 103-113
[10] A. Urbano et al. Combust. and Flame 169 (2016) 129-140
[11] B. Vasques, O. J. Haidn
[12] R. Malpica Galassi et al. Combust. Flame 197 (2018), 439-448
[13] R. Malpica Galassi et al.Combust. Flame 179 (2017), 242-252.