Ivaylo Petkov

System Studies on Active Thermal Protection of a Hypersonic Suborbital Passenger Transport Vehicle

Aerodynamic heating is a critical design aspect for the development of reusable hypersonic transport and reentry vehicles. The reliability in terms of thermal resistance is one of the major driving factors with respect to the design margins, the mass balance and finally the total costs of a configuration. Potential designs of active cooling systems for critical regions such as the vehicle nose and leading edges are presented as well as preliminary approaches for their impact on the total mass. The visionary suborbital passenger transport concept SpaceLiner is taken as a reference vehicle for these studies. Covering the whole flight regime from subsonic to Mach numbers of more than 20, this vehicle creates high demands on the thermal protection system. Part of the work was performed within the DLR research project THERMAS.

Innovative Small Launcher

The market for small satellites is expected to increase substantially in the coming years, but there is little capacity to launch them affordably. No operational dedicated launcher for small satellites exists today. Small satellites, launched as secondary payloads, are entirely dependent on the constraints set by the primary payload, such as launch date and target orbit. Launch costs of less than €50,000 per kg of payload are required in order to directly compete with piggy-back ride shares. With a dedicated launcher a higher cost per kg can be accepted for payloads which need to be delivered timely and accurately to a desired orbit.

Porous Injection Effect on Surface Heat Flux in High-Enthalpy High-Reynolds Number Flow

The experimental study was conducted on transpiration cooling in the free-piston shock tunnel HIEST. Under high-enthalpy and high-Reynolds number conditions, surface heat flux distributions on a flat plate were measured downstream of the C/C porous injector located 140 mm behind the plate leading edge. The test free-stream condition was varied; Stagnation enthalpy was 4 MJ/kg to 14 MJ/kg, the stagnation pressure 14MPa to 50MPa and free-stream Reynolds number was 0.8x10^6/m to 5x10^6/m. Changing the plenum chamber pressure for coolants, the flow-rate of gaseous helium and nitrogen was changed from 0g/s to 5g/s. The effects on surface heat flux of Reynolds number, enthalpy and coolants were discussed.