Toward silent supersonic transport—A fundamental study of supersonic biplane

Abstract

In this research, aerodynamic design of biplane airfoils in supersonic flight is discussed based on computational fluid dynamics (CFD). In supersonic flight, airfoils generate strong sonic booms and wave drags accompanied by shock waves. New airfoil geometries which significantly reduce shock waves using a biplane concept will be proposed. The background of this concept originates from Busemann biplane and Licher type biplane concepts. In order to focus on the shock‐wave characteristics around biplane configuration, inviscid flow (Euler) analyses are performed (which are particularly suitable for wave drag analyses). For the evaluation of the reduction level of shock waves, the wave drag coefficient is used. The design Mach number is 1.7. The aerodynamic design is conducted using an iterative inverse design method that is newly implemented. A biplane configuration with a desired performance has been obtained. Having total maximum thickness ratio of 0.10, it has the lift‐to‐wave‐drag ratio of 21.7 at a desired lift condition for supersonic flight. At the range of lift coefficient more than 0.14 this designed biplane has lower wave drag than that of a (zero‐thickness) single flat plate airfoil. This result will lead to the realization of silent supersonic transport.