Inlet Aerodynamics and Ram Drag of Laser-Propelled Lightcraft Vehicles

Numerical simulations are used to study the aerodynamic inlet properties of three axisymmetric configurations of laser-propelled Lightcraft vehicles operating at subsonic, transonic, and supersonic speeds up to Mach 5. The 60 cm vehicles were sized for launching 0.1-1.0 kg nanosatellites with combined-cycle airbreathing/rocket engines, transitioning between propulsion modes at roughly Mach 5-6. The selected external-compression inlet forebodies included the Mercury nose, a body with a power-law nose, and a body with a parabolic nose—all equipped with cylindrical shrouds. The simulations utilize the Fluent Reynolds-Averaged-Navier-Stokes (RANS) flow solver coupled with the two-equation k - e model for near-wall turbulence. The numerical mesh is generated by the commercial grid generator Centaur 6.0. This package is able to create structured, unstructured, and hybrid meshes around complex geometries. Results provide the pressure, temperature, density, and velocity fields around the three representative configurations as well as the resulting ram drag and total drag coefficients—all as a function of flight Mach number. Given the three alternatives, it is demonstrated that the configurations with the power-law nose and with the parabola nose provide near-optimal geometries for minimum drag during the whole flight trajectory.