Hydrogen peroxide (H₂O₂) is a common chemical, but it also has special uses, like powering rockets. Its most interesting quality is how it can break down very fast when a special material, called a catalyst, is added. This process, called catalytic decomposition, turns hydrogen peroxide into hot water and oxygen gas. This reaction is very powerful and creates a lot of energy, which is perfect for small rocket engines called “monopropellant thrusters.” Our study uses computer tools, called Computational Fluid Dynamics (CFD), to look at this important process. We are doing a Catalytic Decomposition VALIDATION CFD study by checking our computer model against a detailed research paper from the Norwegian University of Science and Technology (NTNU) [1]. This helps us make sure our simulation is very accurate for designing real rocket engines.

• Reference [1]: Vestnes, Frida. A CFD-model of the Fluid Flow in a Hydrogen Peroxide Monopropellant Rocket Engine in ANSYS Fluent 16.2. MS thesis. NTNU, 2016.

Figure 1: Reference plot from the thesis [1] showing absolute pressure and Mach number versus nozzle position, used for Catalytic Decomposition VALIDATION CFD.

Simulation Process: Modeling Hydrogen Peroxide Decomposition in Fluent

To simulate the Hydrogen Peroxide Decomposition CFD process, we first set up our computer model to match a rocket engine nozzle, using a special “axisymmetric” shape (meaning it’s the same all around, like a bottle). We used a very detailed grid of 18,200 tiny boxes to make sure our calculations were accurate. Since the hydrogen peroxide turns into two different things (water and oxygen), we used the Mixture multiphase model in ANSYS Fluent. Because this is a chemical reaction, we also turned on the Species Transport model to track each chemical. A key part of our Catalytic Decomposition Fluent setup was writing a custom computer code, called a User-Defined Function (UDF). We needed this UDF because Fluent’s built-in tools couldn’t handle the exact way our chemical reaction happens. This UDF told the computer how fast the hydrogen peroxide would break down, which is crucial for getting the right results.

Figure 2: Problem description schematic for the Catalytic Decomposition of Hydrogen Peroxide CFD Simulation, illustrating the thermal and catalytic zones.

Post-processing: Validating Flow Dynamics and Thermal Effects

The simulation results provide clear evidence of our model’s accuracy and reveal the dramatic effects of the chemical reaction. The first major confirmation comes from Figure 3, which compares our simulated Mach number (how fast the gas is moving compared to the speed of sound) with the reference paper’s data. The cause is our careful simulation setup, and the effect is a nearly perfect match between our CFD results (blue line) and the paper’s data (orange line) across the nozzle. This strong agreement, especially in the supersonic part of the flow (where Mach number is above 1), is vital. A major achievement of this Catalytic Decomposition VALIDATION CFD study is the precise validation of the Mach number profile, confirming that our simulation accurately captures the complex gas expansion and supersonic flow behavior within the rocket nozzle, which is critical for predicting engine thrust.

Figure 3: Mach number comparison between the Catalytic Decomposition Fluent simulation and reference paper data, demonstrating validation accuracy.

Moving to Figure 4, the temperature contour tells an even more powerful story about the Hydrogen Peroxide Decomposition CFD. The main cause is the chemical reaction itself, which releases a huge amount of heat. The direct effect is a dramatic rise in temperature right after the catalyst bed (the hot red core, reaching nearly 900 Kelvin or 627°C). This intense heat then forms a bright yellow-orange plume that stretches out. This visualization perfectly shows the exothermic nature of the decomposition. The fact that this high temperature is maintained far downstream proves the reaction is complete and efficient. The most important achievement of this Catalytic Decomposition CFD analysis is its ability to accurately visualize and quantify the high-temperature plume generated by the exothermic reaction. This detailed thermal mapping is crucial for engineers to design durable nozzle materials that can withstand extreme heat and optimize the catalytic bed for maximum energy release, directly impacting the performance and safety of monopropellant thrusters.

Figure 4: Temperature contour illustrating the Hydrogen Peroxide Decomposition CFD process, showing the hot plume generated during the exothermic reaction.