Formation of Supercritical Flow Regions on Low-Aspect-Ratio Wings

The flow over a planar low-aspect-ratio delta wing is considered in the strong viscous-inviscid interaction regime. The study is carried out for Newtonian passage to limit, when the adiabatic exponent tends to unity, while the Mach and Reynolds numbers increase without bound. For the flow over a cold wing, an analytical expression for the coordinate of supercritical-to-subcritical transition in the boundary layer is derived. The aspect ratios for which the flow in the three-dimensional boundary layer is subcritical over the entire wing are derived. The approximate formula for the transition coordinate is compared with the results of a numerical solution of the system of differential equations in the case in which the Prandtl number is equal to unity.