This paper describes an experimental investigation into the effect of miniature vortex generators (VGs) on the longitudinal aerodynamic characteristics of a highly-swept wing with drooped leading edges. The experiments were performed in a low-speed windtunnel on a wing of the same delta planform as that used in a previous study. The latter wing was of fixed camber, while the subject of the present study was a wing with three different leading edge droop angles. The maximum reduction in drag due to the VGs was found to be about half that for the fixed-camber wing. This is reconciled with the different behaviour of the flow on the upper surface for the two types of wing. Without control, the drag of the variable-droop wings is much lower than that of the fixed-camber wing. As a result, with control, the variable droop wings have lower drag than that of the fixed-camber wing. Compared to that of the variable-droop wings without control, the fixed-camber wing, with control, has lower lift-dependent drag for lift coefficients between 0·4 and 0·7. However, at higher lift coefficients, the reverse applies.

The aerodynamic interaction between a wing and a couple of propellers in tractor configuration is investigated by means of a model based on the lifting line concept and under the assumption of quasi-steady incompressible motion of inviscid fluid. The ways the propellers influence the wing performances, particularly the induced drag, are analysed. It turns out that the lift increase and the possible drag reduction depend strongly on the direction of the blade rotation and on the propeller distances from midspan, and result from two main effects: the direct propeller induction on the wing and the modification of the lift distribution along the span. An additional nonlinear (mixed) contribution affects the drag but has only negligible influence on the lift. The described model allows one to evaluate separately all these effects and helps understanding their influence on the global modification of the wing performances.

The flow field of a turbulent free jet issuing from a contoured rectangular nozzle of aspect ratio 2 has been studied experimentally, using hot-wire anemometry. The study was undertaken to gain some understanding of the mixing process within the jet. Results of the measured and derived mean flow and turbulence quantities are presented. The three components of the mean velocity vector, the three Reynolds normal stresses, the two Reynolds primary shear stresses, and the flatness factor of the streamwise fluctuating velocity were measured. Mass entrainment, turbulence kinetic energy, and the intermittency factor were derived from the mean streamwise velocity data, the Reynolds normal stress data, and the flatness factor data, respectively. The derived results and the Reynolds primary shear stress data indicate enhanced near-field mixing of the present rectangular jet compared to a round turbulent free jet. The mean streamwise velocity field changes from a rectangular to an oval and then to an approximately circular shape at about twenty equivalent nozzle diameters downstream of the nozzle exit plane.

This paper concerns the study of the three-dimensional interaction of a slat wake and a wing boundary layer, as commonly occurs on the suction surface of a high-lift rnulti-element aerofoil. The experimental test case has a realistic slat-wing flow configuration under infinite swept wing conditions. This enables the effect of the cross flow induced by the wing sweep on the slat wake and the wing boundary layer interaction process to be investigated. A triple hot-wire system has been used to measure the mean velocity and Reynolds stress components in the flow field. The measurements are used to validate a three-dimensional boundary layer code, which has been modified to calculate this three-dimensional wake-boundary layer mixing flow.