Simulating a NASA Hydrogen Powered Rocket

Written by Scott Jorgensen and Kevin Roggendorf

December 12, 2022
NASA hydrogen rocket simulation

Propelling the Orion Spacecraft to the Moon

The recent images of the moon from the NASA Orion spacecraft reminds us of how our technological advancements have made these wonders of the night sky reachable. The Artemis I mission marked an important milestone as it is the closest a human rated spacecraft has come to the moon since the Apollo 17 mission in 1972. This mission is planned to be followed with the Artemis II launch where the Orion spacecraft will host a crew for a lunar flyby.  

We wanted to celebrate this recent achievement in space exploration by highlighting GT-SUITE’s simulation capabilities in the aerospace field and share a model study. To demonstrate the integration of multi-physics domains, a GT-SUITE model was built to replicate the steady state operation of the RL10A-3-3A hydrogen powered rocket. The model was based on data and dimensions found in publications about the RL10A-3-3A rocket engine [1][2].

spacecraft hydrogen powered rocket simulation Modeling the rocket engine’s turbomachinery requires coupling of fluid, mechanical, and thermal domains, along with accurate two-phase fluid properties. The two-stage liquid hydrogen and liquid oxygen pump are powered by the expansion of hydrogen across a turbine, which is made possible through fluid-mechanical coupling. Thermal energy is also recycled from the burnt gases flowing out of the rocket nozzle to aid in powering the turbine. This is accomplished through a fluid to thermal structural connection. Energy from the gases within the rocket nozzle are transferred to the nozzle wall according to the Bartz heat transfer correlation. The nozzle wall is then cooled by hydrogen lines running through it, the turbine utilizes thermal energy added to the hydrogen to power the pumps, circulating energy from combustion back into the system. The hydrogen and oxygen properties are determined according to the NIST subroutine from the REFPROP program to ensure accurate fluid behavior. 

Combustion is modeled with an equilibrium chemistry solver to calculate the composition of burned gases in the combustion chamber so effects of dissociation at high temperatures are considered. In the model it was also found that by solving the chemical kinetics to consider oxidation of radical species as the mixture expands within the rocket nozzle’s diverging section, the accuracy of the heat transfer and thrust predictions were improved. 

Results of Simulating Steady-State Rocket Engine Pressure and Temperature

The results of the GT-SUITE model allow for the visualization of pressure and temperature throughout the rocket engine during steady operation. The thrust and the specific impulse of the RL10A-3-3A engine were also calculated based on flow conditions of the exhaust gases. The GT-SUITE results were shown to match the published RL10A-3-3A performance data well [1][2]. 

steady state pressure distribution of hydrogen rocket engine simulation

Steady State Pressure Distribution of the RL10A-3-3A Engine

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[1] M. Binder. A Transient Model of the RL10A-3-3A Rocket Engine. Contractor Report NASA CR-195478, NASA, July 1995. 

[2] Matteo, Francesco Di, et al. “Transient Simulation of the RL-10A-3-3A Rocket Engine.”