Optimal artificially blunted leading-edge airfoils for enhanced aerothermodynamic performance

An artificially blunted leading edge concept that can be applied to the blunted leading edges of vehicles in hypervelocity Eight for drag reduction is described. By creating a channel sized to choke at the design condition, most of the wall on which the stagnation region pressure acts is removed; this results in significantly reduced total drag. To evaluate the effectiveness of airfoils employing this concept in achieving low drag without paying any penalties in other areas like lifting capacity, heating rates, or enclosed volume, the design space is characterized comprehensively using multidisciplinary design optimization techniques. Response surface methods are used to search the design space efficiently for such airfoils designed to operate at Mach 4 and 12-km altitude. The results from a designed set of numerical experiments, i.e., Navier-Stokes simulations, are used to create analytical models for force coefficients and peak heat transfer rates. These nonlinear models are then used to generate an optimal channel airfoil design. The performance predicted by the models is verified by Navier-Stokes solutions to validate the optimal design and to evaluate the efficacy of the concept evaluation technique. The optimal airfoil had a 19% lower ed and a lower peak heat transfer rate while providing the same cr and enclosed area as the baseline (4% thick) blunted diamond airfoil. The models were accurate to within 5% of the calculated values and demonstrated the ability to smoothly capture trends in system responses while filtering out numerical noise.