Stratos IV

Stratos is the most important project within the TU Delft student team of DARE. With this project they aim to reach space (100 km altitude) with a self-built rocket. As a sponsor, One Simulations provides advice and CFD simulations of the complex physics to support the student team. The cooperation mainly concerns determining the air resistance and the stability of the supersonic rocket.

CFD Simulations

With CFD simulations, the rocket was simulated during 5 moments of its flight. The flight speed varies from 37 m/s (Mach 0.11) to a high supersonic flight speed of 1,238 m/s (Mach 4.1). The supersonic hot flame from the rocket engine is also simulated.

The figures show the origin of the shock waves around the nose cone and at the stabilizer fins. The so-called “Shock cells” are clearly visible at Mach 0.11 at the rocket engine as alternating high pressure (red color) and low pressure (blue color).

CFD Simulations

With CFD simulations, the rocket was simulated during 5 moments of its flight. The flight speed varies from 37 m/s (Mach 0.11) to a high supersonic flight speed of 1,238 m/s (Mach 4.1). The supersonic hot flame from the rocket engine is also simulated.

The figures show the origin of the shock waves around the nose cone and at the stabilizer fins. The so-called “Shock cells” are clearly visible at Mach 0.11 at the rocket engine as alternating high pressure (red color) and low pressure (blue color).

When the rocket is at its highest point, the nose cone is separated from the rest of the rocket and then landed safely on a parachute on Earth. Before the parachute is activated, the nose cone makes a long free fall. The 6 DoF (Degrees of Freedom) solver of Ansys Fluent was used to calculate the movement and the resulting forces and temperatures on the nose cone. In the simulation, the nose cone can move freely due to the calculated aerodynamic forces.

In the animation below, the nose cone has been released at an altitude of 133 km. Due to the lack of air resistance, the nose cone accelerates in 120 s to a maximum speed of 1,085 m / s. From this moment on at an altitude of 65 km, the air resistance increases and the nose cone slows down. This results in a chaotic fall and high temperatures at the nose cone.

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Chief Simulations Stratos IV:

“The results of the center of pressure values ​​quickly provided clarity (and relief) to our team about the stability of the rocket. Also the results of the falling nose cone were great to see and gave us certainty about which drag coefficient to use to simulate the unstable nose cone with a 3-DoF simulation. Finally, I really appreciated the help offered when we had problems with CFD ourselves."