A Rotating Detonation Combustor (RDC) is a novel propulsion system that uses rotating detonation waves to produce efficient and high-performance combustion. Unlike typical combustion systems, which rely on deflagration (subsonic combustion), RDCs use detonation, a supersonic combustion process characterized by rapid pressure rise and high energy release. In an RDC, fuel and oxidizer are pumped into a chamber and ignited in a continuous detonation wave that rotates around the combustion chamber’s surface. RDCs are a promising field of research in aerospace engineering and propulsion technology, potentially transforming future generations of aircraft and rocket engines.

Although it is one of the most challenging types of combustors, it is simulated in this project. So, a Rotating Detonation Combustor is conducted in order to investigate flow behavior as it moves. It should be noted that many reference papers are used to make proper assumptions, as listed below:

• Reference [1]: Zhuo, Chang-Fei, et al. “Numerical Investigation of Air Vitiation Effect on the Rotating Detonation Engine.” Journal of Applied Science and Engineering4 (2018): 555-562.
• Reference [2]: Escobar, Sergio, et al. “Numerical investigation of rotating detonation combustion in annular chambers.” Turbo Expo: Power for Land, Sea, and Air. Vol. 55102. American Society of Mechanical Engineers, 2013.

Figure 1: Schematic of how Rotating Detonation Combustor (RDC) works

Simulation Process

Due to the assumption of 2-dimensional investigation, the geometry is simple and easily designed using ANSYS Design Modeler software. Then, it is meshed in ANSYS meshing using a structured grid. The supersonic flow requires a high-quality mesh grid.

Next, in the solver setting, there are several challenges. Firstly, it goes without saying that in supersonic flows, the density does not remain constant, so a density-based solver is employed. Also, the fluids are not viscose anymore and we can assume an inviscid governing equation. Methane and oxygen participate the reaction after the mixture and produce carbon dioxide and water vapor. So Species Transport model regarding volumetric reactions is activated. Finally, a user-defined function (UDF) is written to consider inlet velocity, which is a function of local pressure, temperature, nozzle geometry, nozzle outlet pressure, etc.

Post Processing

The RDC’s operational state is dominated by supersonic combustion dynamics, where methane-oxygen detonation waves provide a fascinating simulation of extreme thermodynamic conditions. Shock-induced compression at the detonation front produces chemical reactions that happen almost instantly, accelerating local velocities above 2000 m/s. The velocity field displays clear compression-expansion patterns produced by these waves, which rotate at kilohertz frequency. The flow quickly expands behind each wave, creating distinctive diamond shock structures that illustrate the intricate relationship between gas dynamics and geometry constraints. These waves are forced into a self-sustaining rotation by the annular shape of the chamber, ejecting high-temperature products at supersonic speeds and consuming new reactants with each cycle.

Figure 2: Velocity Contour

Within milliseconds of initiation, the combustion chamber develops into a high-energy reaction vessel where conventional fluid mechanics cross with detonation physics. The species transport model suggests quick transitions from reactant-rich zones to product-dominated areas, with reaction completion occurring within microseconds. Local temperatures exceed 3000K as the detonation front compresses and ignites the fuel-oxidizer mixture, while pressure ratios surpass 20:1 across the wave front. The inviscid flow assumption is particularly advantageous here, as viscous effects become insignificant relative to the current pressure-driven phenomena. Notably, multiple detonation waves form, each sustaining stable propagation despite extreme gradients in pressure, temperature, and species concentration. This self-organizing behavior illustrates the RDC’s intrinsic stability mechanisms, essential for practical propulsion applications.