Inverse design method for the Licher biplane with a new target pressure distribution

An inverse design method has been applied for the Licher biplane with modern computational fluid dynamics (CFD) technique to increase the lift-drag ratio and reduce the shock wave drag during its the supersonic flight regime. An example of numerical simulation demonstrates that the wave drag can be reduced by 25.5% and the lift-drag ratio rises by 30.5% simultaneously using this optimization algorithm with inviscid flow assumption as the free stream Mach number is 1.7. In addition, it takes about 15 iterations to get convergent results, which demonstrates that the inverse design method in this paper is efficient. A new stair target pressure distribution, as the key of the inverse design method, has been developed to overcome setbacks of the original one by some analyses of aerodynamic forces. With the new target, the lift-drag ratio can increase up to 49.8%. Furthermore, the Euler equations in the optimization procedure have been replaced by the Navier-Stokes equations to investigate the influence of viscous fluid. The results indicate that the effect of the optimization with the original target pressure distribution is beyond neglect, the lift-drag ratio increases only by 17.0%. However, the results of the new stair target pressure distribution, with more potential practical value, stay almost the same level.