Simulating the “Impossible”? Automation Meets Rotating Detonation Engines

Enabling Rotating Detonation Engine (RDE) Innovation Through Simulation and Automation

The Rotating Detonation Engine (RDE) stands out as a leading technology that can advance performance and efficiency for future propulsion systems. Simulation software plays a critical role in accelerating development and tackling complex design challenges while engineers and researchers strive to unlock the full capabilities of this innovative technology. This blog explores the application of GT-SUITE together with automation for developing detailed and precise RDE models that generate 10,000 flow volumes within hours. This blog will cover RDE fundamentals alongside modeling methods and illustrate how automation transforms daunting tasks into achievable engineering achievements.

What is a Rotating Detonation Engine?

Some of you may read the title and wonder “What is a Rotating Detonation Engine?” (RDE). An RDE is a groundbreaking advancement in propulsion technology that is being actively researched by NASA, universities and research labs, established jet engine companies and start-ups. Unlike traditional engines that rely on a flame spreading through the combustion chamber at subsonic speeds, RDE’s use controlled detonation waves that travel at supersonic speeds to burn the air-fuel mixture. This innovative approach allows for the rapid generation of high-pressure and high-temperature gases, leading to significant improvements in thermal efficiency that will result in lower fuel consumption. Another key advantage of this technology is the significant reduction in moving parts, thus simplifying maintenance. However, RDE’s face challenges such as maintaining stable detonation waves, managing extreme temperatures and pressures, and optimizing components like nozzles and injectors for better performance that require study and design. The images below help illustrate the ideas behind the system.

Figure 1 Rotating detonation engine

Figure 2 Unwrapped view of the RDE, illustrating the various regions. Colors represent temperature ranging from ≈500K (blue) to ≈3500K (red)

We at Gamma Technologies have received several inquiries on whether GT-SUITE can be used to simulate such engines. We considered developing a detailed combustion model specifically for this combustion device, but it was estimated to take as much as a thousand hours to develop, and we were not sure whether the long-term demand was large enough to justify such an investment of time. However, with some creative thinking — leveraging existing capabilities in the GT-SUITE solver and features available in GT-Automation — we were able to develop a working solution in less than a hundred hours.

Simulation Methodology for Rotating Detonation Engines (RDE)

Simulation of the RDE involves complex interactions of high-speed fluid dynamics with fast chemical kinetics. The fully compressible and transient flow solver plus the integrated chemical kinetic solver in GT-SUITE allows the capture of this intricate interplay, simulating the dynamics of the entire combustion process and the movement of the shock wave through the combustor. Using GT-SUITE’s modular architecture we were able to build a comprehensive model for this combustor from scratch using existing capabilities in the software. Such a model involved discretizing the annular volume of the RDE using discrete flow volumes, both in the circumferential and axial directions, as shown in Figure 3. This resulted in a total of about ten thousand flow volumes, all interconnected with each other and with parts simulating chemical kinetics.

Automation-Driven Modeling for RDEs: Building 10,000 Flow Volumes in Hours

You may have read the part about ten-thousand flow volumes being built in the model and wondered, “how long would it take to build that model?” or “does your hand hurt after clicking the mouse that many times?”.  These are good questions to ask, and you may be relieved to learn that no carpal tunnel syndrome was triggered while building this model.  The possibility to build and modify models in GT-ISE through Python scripting and API’s by using GT-Automation was remembered and used to move forward quickly.

If you are not already familiar with it, GT-Automation is a time-saving enterprise package in GT-SUITE that enables Python scripting of GT-ISE and GT-POST operations, as well as process integration of modeling and simulation tasks. With GT-Automation, users can save time and eliminate errors that often come from repeated, tedious operations. In this instance, a Python script was written that automated the entire model building process, allowing us to quickly adapt to changes in discretization, geometry and operating conditions while significantly reducing the time and potential errors associated with manual modeling. This led to the development of an innovative quasi-3D modeling methodology using GT-SUITE, which has the potential for rapid simulations of RDEs at both the component and system levels. Also, by creative use of the existing capabilities of GT-SUITE and GT-Automation, this model was developed with no changes or additions to the physics-based solvers and completed in less than one hundred hours, providing a lot of cost-savings compared to a specialized development.

Here is a video showing the building of the model in GT-ISE that results from running the Python script in GT-Automation:

Video showing the building of the model in GT-ISE that results from running the Python script in GT-Automation

To help you understand the model in relation to the device, Figure 2 is shown again with some flow parts overlaying the image.

Figure 3 Unwrapped view of the RDE, illustrating the quasi-3D simulation methodology

What is predicted?

Some results of these simulations are shown in Figure 4, below.

Figure 4 (a) Unwrapped view showing single and dual detonation wave propagation patterns (co- and counter-rotating configurations) (b) 3D view of the RDE. Colors in (a) and (b) represent temperature ranging from ≈500K (blue) to ≈3500K (red) (c) Variation of thrust with injection area, parametrized by increasing injection pressure (d) Temporal evolution of pressure close to the injection plane. Injection pressure (dashed line) shown for comparison

These results demonstrate the model’s capability to capture realistic RDE behavior, including:

• Detonation Wave Motion: Both single and multiple waves (co- and counter-rotating) can be simulated effectively.
• Performance Influences: The impact of injection parameters on engine performance has been demonstrated.
• Limit Cycle Operation: The system can achieve a stable, periodic state, which is crucial for reliable engine operation.

As a bonus, the 3D animation capabilities of GT-SUITE were used to create this video for your viewing pleasure:

3D animation video of detonation wave motion

Accelerating RDE Model Development Using GT-SUITE and GT- Automation

This project turned out to be a great demonstration of the capabilities and flexibility of GT-SUITE as a simulation platform and multi-physics solver. A project that was intimidating in size, scope and effort at the beginning turned into a manageable task in the end, yielding realistic results and exciting animations. GT-Automation was a critical component in empowering the team to build this model with a relatively low effort. If you are interested in learning more about how GT-Automation can support your projects, please visit our web page on the topic (GT-Automation) or contact us! You can also watch our webinar on GT-Automation, and check out our blogs on Hydrogen-Powered Rocket simulation and how engine manufacturers leverage simulation to stay ahead of increasing regulations.