THE BOUNDARY LAYER THERMAL PROTECTION SYSTEM: AN ADVANCED CONCEPT FOR PROTECTING HOT STRUCTURES DURING RE-ENTRY

Observation of the heat flux distribution along s pherecone and cy linder-wedge geometries at hypersonic reentry conditions has recently suggested to eliminate the Thermal Protection Systems (TPS) that typically cover the conventional aeronautical structures of re-entry vehicles. The strong heat flux reduction downstream of a sharp vehicle nose (and of the wing leading edges) appears to be compatible with the use of hot structures downstream of a Ultra High Temperature Ceramics (UHTC) insert at th e tip. By p ositioning the n ew massive TPS only at the front tip of the fuselage and at the l eading edge of the wings, l ight structures a nd l ow wing loading can be realized and a shallow long reentry is made possible. The paper shows typical re-entry trajectories and reports aerothermodynamic co mputations at the most severe thermal re-en try co nditions. The concept of Boundary Layer Thermal Protection System (BLTPS) is illustrated with reference to possible geometries. The aerothermodynamic field and the temperature distribution in the so lid structure are simultaneously solved, tak ing in to account ch emical non equilibrium, catalysis and thermal conductivity of the UHTC materials.