Transcritical Behavior of Methane in the Cooling Jacket of a Liquid-Oxygen/Liquid-Methane Rocket-Engine Demonstrator

Abstract

The successful design of a liquid rocket engine is strictly linked to the development of efficient cooling systems, able to dissipate huge thermal loads coming from the combustion in the thrust chamber. Generally, cooling architectures are based on regenerative strategies, adopting fuels as coolants; and on cooling jackets, including several narrow axial channels allocated around the thrust chambers. Moreover, since cryogenic fuels are used, as in the case of oxygen/methane-based liquid rocket engines, the refrigerant is injected in liquid phase at supercritical pressure conditions and heated by the thermal load coming from the combustion chamber, which tends to experience transcritical conditions until behaving as a supercritical vapor before exiting the cooling jacket. The comprehension of fluid behavior inside the cooling jackets of liquid-oxygen/methane rocket engines as a function of different operative conditions represents not only a current topic but a critical issue for the development of future propulsion systems. Hence, the current manuscript discusses the results concerning the cooling jacket equipping the liquid-oxygen/liquid-methane demonstrator, designed and manufactured within the scope of HYPROB-NEW Italian Project. In particular, numerical results considering the nominal operating conditions and the influence of variables, such as the inlet temperature and pressure values of refrigerant as well as mass-flow rate, are shown to discuss the fluid transcritical behavior inside the cooling channels and give indications on the numerical methodologies, supporting the design of liquid-oxygen/liquid-methane rocket-engine cooling systems. Validation has been accomplished by means of experimental results obtained through a specific test article, provided with a cooling channel, characterized by dimensions representative of HYPROB DEMO-0A regenerative combustion chamber.

Thermal Behaviour of the Cooling Jacket Belonging to a Liquid Oxygen/Liquid Methane Rocket Engine Demonstrator in the Operation Box

“…The specific heat, shown in Figure 15b, has maxima lying over a range of positions from x/L = 0.42 to 0.54, which are associated with average pseudo-critical conditions and depend on the inlet conditions and input heat flux imposed by the points considered in the limiting box. In particular, as discussed in [56], the inlet temperature plays an important role, and, if it is increased, the maximum of the specific heat capacity distribution moves in the throat direction and attains higher values, as shown by the results associated with Points A and D. Comparing the temperature axial profiles and results for the specific heat, the deterioration mode, described by several authors in the literature [55,[57][58][59] in the DEMO operative box, is absent since the temperatures in the vicinity of the pseudo-critical point are controlled and maintained below throat and re-attachment point section values. This is due to the care taken in the design phase to avoid this phenomenon by defining suitable geometric features and the choice of surface roughness [60].…”

Regenerative Cooling Comparison of LOX/LCH4 and LOX/LC3H8 Rocket Engines Using the One-Dimensional Regenerative Cooling Modelling Tool ODREC

“…In order to test ODREC, the results of the study carried out by Ricci et al [39] were reproduced. In that study, the authors analyzed the regenerative cooling of a 30 kN thrust class LOX/LCH 4 engine demonstrator that operates at an oxidizer-to-fuel ratio of 3.4 and a combustion chamber pressure of 55 bar [40].…”

Analysis of the Sum Minimization Possibilities of Heat Exchanger Core Masses in Internal Combustion Engine Cooling Systems

“…Fundamentally different cooling systems are also under consideration. A comprehensive review of modern adsorption refrigeration systems is provided in [17,18]. However, these systems are characterized by significant dimensions, making their practical use challenging.…”