Supersonic Natural-Laminar-Flow Wing-Design Concept at High-Reynolds-Number Conditions

This paper describes an effective method to create a new ideal pressure distribution for designing a three-dimensional natural-laminar-flow wing at high-Reynolds-number conditions to reduce friction drag of a large-size supersonic transport with 300 passengers. This ideal pressure distribution consists of a useful functional form with parameters that are adjusted to be widely applicable to general wing planforms. Furthermore, this research proposes an improvement to the design flow of a conventional computational-fluid-dynamics-based inverse design method developed previously by the Japan Aerospace Exploration Agency for a natural-laminar-flow wing design. An idealized pressure distribution and its validity to achieve approximately 35% laminar flow region of the wing surface on a cranked arrow type planform are presented at the condition of Mach 2.0 and high Reynolds number of approximately 126 million based on mean aerodynamic chord. A representative cross-sectional shape of the designed wing is introduced as an example, and it is shown that a distinguishing feature is characterized by a smaller curvature near the attachment line. A further ideal pressure distribution for an Ogee-type planform with swept angle varied continuously in spanwise direction is then created as a test case for more complicated planforms.