This paper describes an experimental investigation intothe effect of miniature vortex generators (VGs) onthe longitudinal aerodynamic characteristics of ahighly-swept wing with drooped leading edges. Theexperiments were performed in a low-speed windtunnelon a wing of the same delta planform as that used ina previous study. The latter wing was of fixedcamber, while the subject of the present study was awing with three different leading edge droop angles.The maximum reduction in drag due to the VGs wasfound to be about half that for the fixed-camberwing. This is reconciled with the differentbehaviour of the flow on the upper surface for thetwo types of wing. Without control, the drag of thevariable-droop wings is much lower than that of thefixed-camber wing. As a result, with control, thevariable droop wings have lower drag than that ofthe fixed-camber wing. Compared to that of thevariable-droop wings without control, thefixed-camber wing, with control, has lowerlift-dependent drag for lift coefficients between0·4 and 0·7. However, at higher lift coefficients,the reverse applies.

The aerodynamic interaction between a wing and a coupleof propellers in tractor configuration isinvestigated by means of a model based on thelifting line concept and under the assumption ofquasi-steady incompressible motion of inviscidfluid. The ways the propellers influence the wingperformances, particularly the induced drag, areanalysed. It turns out that the lift increase andthe possible drag reduction depend strongly on thedirection of the blade rotation and on the propellerdistances from midspan, and result from two maineffects: the direct propeller induction on the wingand the modification of the lift distribution alongthe span. An additional nonlinear (mixed)contribution affects the drag but has onlynegligible influence on the lift. The describedmodel allows one to evaluate separately all theseeffects and helps understanding their influence onthe global modification of the wingperformances.

The flow field of a turbulent free jet issuing from acontoured rectangular nozzle of aspect ratio 2 hasbeen studied experimentally, using hot-wireanemometry. The study was undertaken to gain someunderstanding of the mixing process within the jet.Results of the measured and derived mean flow andturbulence quantities are presented. The threecomponents of the mean velocity vector, the threeReynolds normal stresses, the two Reynolds primaryshear stresses, and the flatness factor of thestreamwise fluctuating velocity were measured. Massentrainment, turbulence kinetic energy, and theintermittency factor were derived from the meanstreamwise velocity data, the Reynolds normal stressdata, and the flatness factor data, respectively.The derived results and the Reynolds primary shearstress data indicate enhanced near-field mixing ofthe present rectangular jet compared to a roundturbulent free jet. The mean streamwise velocityfield changes from a rectangular to an oval and thento an approximately circular shape at about twentyequivalent nozzle diameters downstream of the nozzleexit plane.

This paper concerns the study of the three-dimensionalinteraction of a slat wake and a wing boundarylayer, as commonly occurs on the suction surface ofa high-lift rnulti-element aerofoil. Theexperimental test case has a realistic slat-wingflow configuration under infinite swept wingconditions. This enables the effect of the crossflow induced by the wing sweep on the slat wake andthe wing boundary layer interaction process to beinvestigated. A triple hot-wire system has been usedto measure the mean velocity and Reynolds stresscomponents in the flow field. The measurements areused to validate a three-dimensional boundary layercode, which has been modified to calculate thisthree-dimensional wake-boundary layer mixingflow.