An experimental investigation of the transonic flow over an unswept wing of aspect ratio 3.5, taper ratio 0.5, with a 4 per cent biconvex section

Abstract

The results of force measurements and surface oil flow studies on a wing-body combination with an unswept wing of aspect ratio 3.5, taper ratio 0.5, and a 4 per cent biconvex section, are analysed. The tests were made at Mach numbers from 0.72 to 1.02, at a Reynolds number of 1.89 × l0power6. At four Mach numbers, 0.70, 0.80, 0.93 and 0.96, a picture of the flow development with incidence is built up, based on the oil flow patterns on the wing, and a correlation is established between changes in overall forces, and changes in tile flow development. At other Mach numbers the flow development is inferred from the overall forces by means of this correlation, and, in this way, an attempt is made to show how transonic flow develops over the wing. At transonic Mach numbers four phases in the development of the flow with incidence are found. These are (a), no shock-induced separation, (b), shock-induced separation, with the shock roughly stationary on the wing, (c), shockinduced separation, with a rapid forward movement of the shock, and (d), leading edge separation. The aerodynamic derivatives are found to assume roughly constant values in each phase, and their variation with phase and Mach number is considered.