Supersonic Flow over SR-71 Blackbird Numerical Aproach

Summary of Supersonic Flow over Blackbird Aircraft CFD Simulation, SR- 71

Project Description

Using ANSYS Fluent, this project models the supersonic flow over an SR-71 Blackbird aircraft.  In dry air at 20°C, suersonic speed is defined as speeds above the speed of sound, roughly 343 m/s.  Traveling at 446 m/s in this simulation, the SR-71 aircraft produces a Mach number of 1.3 with a 2-degree angle of attack.

Geometry and Meshing

• Geometry Design: Design Modeler imports the three-dimensional geometry of the SR-71 Blackbird and positions it inside an enclosure.
• Initial Meshing: Unstructured mesh produced with ANSYS Meshing with 1,744,624 components.
• Mesh Conversion: ANSYS Fluent transformed tetrahedron mesh to polyhedra for improved simulation accuracy.

Methodology: Supersonic Flow over SR-71 Blackbird Aircraft

• Solver Type: Pressure-based solver modelling compressible flows by include ideal-gas behaviour of air density using a coupled pressure-velocity algorithm.
• Simulation Type: performed in steady state with the Sutherland model modeling viscosity as a function of temperature.

Conclusion

Over the SR-71 aircraft, the simulated supersonic flow (Mach number 1.3) emphasizes important observations:

• Solver Choice: Although compressible flow usually employs a density-based solver, a pressure-based solver was efficiently applied using the linked velocity-pressure technique.
• Shock Waves: Extreme velocity and pressure gradients were found near the nose and engines of the aircraft from shock waves.
• Density Variations: Important density differences verified the need of including compressibility into the model.
• Correlation: Pressure, density, and temperature showed the expected direct link.