A Solar Thermal Propulsion System CFD simulation is a computer model of a special kind of rocket. These Solar Rocket CFD systems are advanced because they use the Sun’s energy to heat a gas, instead of burning chemical fuel. This Spacecraft Propulsion Simulation is very important for long space missions where saving fuel is critical. The analysis helps engineers understand how heat from the sun moves into the gas and how this hot gas creates thrust. A Solar Thermal Propulsion System Fluent model can show the temperature and speed of the gas inside the rocket. Using ANSYS Fluent, we can perform a Nozzle Performance Analysis to make sure the rocket design is efficient. This type of High-Temperature Gas Dynamics study is essential for creating powerful and reliable rockets for future space exploration.

Figure 1: A simple sketch of the solar thermal propulsion system, showing the main parts like the absorber and thruster

Simulation process: Fluent Setup, Axisymmetric Compressible Flow Modeling

To perform this Solar Thermal Propulsion System CFD study, we created a model of the rocket engine. The engine has a cylindrical heating chamber and a special nozzle to create thrust. We used a 2D axisymmetric model because the rocket is symmetrical around its center line. This method saves a lot of computer time but still gives accurate 3D results for this shape. We then used ANSYS Meshing to build a structured mesh. This type of mesh has organized, square-like cells that align with the flow direction, which is very good for accuracy in high-speed simulations. In the ANSYS Fluent solver, we used the pressure-based solver. The gas was modeled as an ideal gas, which is a good assumption for propellants like hydrogen at very high temperatures. We told the simulation that a constant amount of heat was being added to the chamber walls, which represents the focused energy from the sun.

Figure 2: The high-quality structured mesh used for the Solar Rocket CFD simulation, with finer cells in the heating chamber and nozzle throat

Post-processing: CFD Analysis, Energy Conversion and Supersonic Thrust Generation

The results of this simulation clearly show that the solar thermal rocket design is very effective. From an engineering standpoint, the most important process is changing heat energy into kinetic energy (speed), and the temperature contours in Figure 3 show this perfectly. The gas reaches a very high temperature of 2230 K in the heating chamber (red area). As this hot gas flows through the nozzle, it expands and cools down to 157 K at the exit. This large temperature drop of 2000 K is not a loss; it is direct evidence that the heat energy has been successfully converted into the speed that creates thrust. This energy conversion is also proven by the density and velocity results. The density contours in Figure 4 show the gas density drops from 246.5 kg/m³ in the chamber to just 0.46 kg/m³ at the exit. This happens because as the gas gains speed, its molecules spread farther apart. The velocity contours in Figure 5 show the final result of this process. The gas starts very slow in the chamber and accelerates to an extremely high exit velocity of 1951 m/s (red area). The smooth increase in speed through the nozzle confirms the design is excellent and does not have any shock waves that would reduce performance.

Figure 3: Temperature contours from the Fluent simulation, showing the high-temperature chamber and the cooling of the gas as it expands through the nozzle.

Figure 4: Density contours showing how the gas density decreases as it accelerates, a key feature of Compressible Flow Simulation.

Finally, the turbulence contours in Figure 6 give us more insight. The highest amount of turbulence (2.76×10⁶ m²/s²) is found in the nozzle throat. This intense mixing is actually good for performance because it helps transfer heat evenly through the gas just before it rapidly expands. The turbulence then decreases in the nozzle, showing the flow is becoming smooth and organized, which is ideal for producing maximum thrust.

The most important achievement of this simulation is demonstrating the successful conversion of solar heat into a high-velocity exhaust stream of 1951 m/s. The analysis confirms that the system can reach the necessary 2520 K chamber temperature and that the nozzle efficiently turns this thermal energy into kinetic energy, validating the design as a high-performance solar thermal propulsion system.

Figure 5: Velocity contours revealing the acceleration of the propellant gas to supersonic speeds, a result of the Nozzle Performance Analysis Fluent.

Figure 6: Turbulence Kinetic Energy (TKE) contours showing the areas of intense mixing, especially in the nozzle throat.