For decades, researchers have recognized the potential of rotating detonation engines (RDEs) in powering the next generation of hypersonic air-breathing engines, rocket engines, and stationary power generation gas turbine systems. But realizing the potential has been fraught with challenges.
Still in the experimental stage, RDEs are an innovative power generation and propulsion technology that utilize supersonic detonation waves to combust fuel. By extracting energy with remarkable efficiency, RDEs have potential advantages over traditional gas turbine engines, including increased effectiveness and reduced emissions.
While mechanically simple, the unsteady combustion process is highly complex, making the technology extremely difficult to study and develop with traditional methods.
Computer modeling and simulations can play a critical role in helping scientists and engineers better understand the key physics behind the inner workings of RDEs and develop strategies to improve their design. Specifically, RDEs have the potential to be an ultra-high-efficiency alternative to conventional gas turbine engines.
In a new collaboration, the U.S. Department of Energy’s (DOE) Argonne National Laboratory and DOE’s National Energy Technology Laboratory (NETL) are leveraging their expertise in RDEs to develop advanced computational fluid dynamics (CFD) tools that can give scientists a deeper understanding of the combustion process to unlock more of the engine’s potential. They are also looking to make the modeling process faster and more affordable without sacrificing predictive accuracy.
As part of this effort, Argonne is exploring and analyzing RDEs using advanced combustion modeling and unique high-fidelity CFD simulation tools. Scientists are also leveraging Argonne’s world-class supercomputing and artificial intelligence capabilities to enable computationally efficient simulations of full-scale RDEs.
NETL is contributing experimental test data from its state-of-the art high-pressure RDE facilities to help verify and validate Argonne’s novel CFD simulation tools. NETL leads the RDE experimental research program focused on transitioning this promising technology to the power generation industry.
“As part of Argonne’s groundbreaking work on combustion modeling and high performance computing, scientists have been actively researching RDEs to advance power generation and propulsion technologies,” said Sibendu Som, Director of the Advanced Propulsion and Power Department at Argonne. “The collaboration between Argonne and NETL leverages key strengths of both national labs and has the potential to truly accelerate the development of RDE technology for ground-power applications.”
Among its advantages, RDEs are highly compatible with natural gas and blends with alternative fuels such as hydrogen, which is critical to the future of stationary power generation. Stationary power generation systems, such as gas and steam turbines, are used in power plants to generate electricity.
“Apart from the efficiency gains, the simplicity of design and potential for use with hydrogen and hydrogen-natural gas blended fuels make RDEs a promising technology that could be integrated into existing power grids,” according to project collaborator Don Ferguson, Research Engineer with the Thermal Sciences group at NETL’s Research & Innovation Center.
In addition, aerospace companies and governments around the world are actively pursuing RDEs which could revolutionize space exploration through benefits like greater effectiveness and reduced weight compared to traditional rocket engines.
While significant advances have been made in high-speed experimental diagnostics, the unsteady and chaotic nature of the RDE combustion process can make it difficult to adequately characterize the important chemical and physical processes. Computer simulations can help to provide additional information that is critical for optimizing RDE designs.
But computer simulation of RDEs isn’t without hurdles. These engines have complicated unsteady physics involving flow turbulence, shockwaves, chemical kinetics and wall heat transfer. Because the interaction among these phenomena is not well understood, they are not incorporated into current CFD modeling approaches. RDE performance is also tied heavily to the design of the combustion chamber and fuel/air feed systems.
“CFD models need to account for the full-scale geometry and complex physics so that simulations of RDEs can be predictive. But on the flip side, this leads to high computational expense,” said Pinaki Pal, a Senior Research Scientist at Argonne and principal investigator of the project. “The gap between predictive accuracy and computational efficiency of RDE simulations is what we hope to bridge through this research effort.”
To accomplish project goals, researchers are leveraging Argonne’s unique high-fidelity CFD and so-called reduced-order, or simplified, combustion modeling tools.
Scientists are using Argonne’s groundbreaking Nek5000 flow solver that can solve CFD problems with remarkable speed and precision. The code is designed to run efficiently on massive supercomputers and combines cutting-edge mathematical techniques with flexible modeling of complex shapes and systems.
Recent upgrades have expanded Nek5000’s capabilities to modeling of high-speed compressible reacting flows. High-fidelity datasets from these Nek5000 simulations will be used to develop turbulent combustion and wall heat transfer models to enhance understanding of RDE physics. These models will then be used in faster, full-scale engine simulations, which will be tested against experimental data from NETL.
“Speeding up RDE simulations while achieving high accuracy will enhance the reliability of CFD tools and significantly reduce the time-to-solution. This will be key for industry to accelerate design cycles for RDE technology and help the U.S. meet future energy efficiency goals,” said Pal.
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