A fundamental study is presented of the three-dimensional aspects of the wake/boundary layer interaction as it occurs on high-lift wings, particularly the slat-wake/wing boundary layer interaction. A digital system for measuring and recording all the components of the mean velocity and the Reynolds stress tensor using a triple hot-wire probe has been developed. This system has been tested and has been used to measure the interaction between the wakes of swept aerofoils and the fully turbulent boundary layer developing on a flat plate. An important and interesting result of all the tests is the rapid decay of the three dimensionality in the wake, so that in many cases the actual interaction is almost two-dimensional. Two cases of three-dimensional interaction have been simulated. In one case the interaction is fully three-dimensional while in the other case it can be assumed to be quasi three-dimensional. For the quasi three-dimensional confluent flow, the measured results have been compared with the predictions of the two-dimensional form of K-ε and algebraic stress turbulence models. The overall agreement between the measured and predicted results is good. However, for the turbulence flow field the agreement is less satisfactory in the initial mixing region where the three-dimensionality is strong and it is also poor in the wall boundary layer.

Detailed measurements of atmospheric-turbulence velocity have been made by a specially instrumented aircraft at altitudes below one thousand feet over a variety of terrains. These measurements are analysed in terms of power-spectral-density and a statistical-discrete-gust model. To a good approximation, spatial increments in turbulence velocity are shown to satisfy scaling laws implying self-similarity for amplitudes up to about four times their root-mean-square value and over a wide range of scales. A three-parameter relationship is established between two parameters from the statistical-discrete-gust analysis, corresponding respectively to intermittency and gust intensity, and one from the power-spectral representation, related to the average rate of energy dissipation.

A low-order panel method is presented for the calculation of subsonic or supersonic linear flow about general configurations. The method uses piecewise constant source, doublet and/or vorticity singularities. The internal Dirichlet boundary condition is applied, providing zero perturbation potential inside the configuration. The external Neumann boundary condition may refer to a condition on the outward conormal component of the perturbation velocity (the so-called 'linearised normal mass flux'). However, the program may, if required, proceed to obtain specified conditions on the outward normal component of the perturbation velocity, using an iterative procedure.

Discharge coefficients for annular orifices formed between pistons and a cylindrical bore are reported for twelve pistons having orifice length to gap ratios in the range 12 to 50. Square-edged, radiused and tapered orifices are examined at high fluid pressure differentials with Reynolds number varying in the range 500-4000. The radial gaps were determined by examining the flow for each piston geometry at low Reynolds numbers.