The paper reproduces the results of an earlier report on the vortex theory of windmills and follows that theory through to establish the aerodynamic design procedure for a horizontal axis windmill. The results are shown to differ considerably from those given in a recent paper by Griffith and the differences are explained. The main conclusion is that, when full allowance is made for the drag of the blades, hub and tip losses, and losses due to interference with the support tower, the power output coefficient or efficiency of a horizontal axis windmill cannot exceed 30 to 35 per cent, as compared to an ideal efficiency of 59 per cent.

This paper presents a theoretical study of the confluence of three shock waves in three-dimensional flow. A suitable transformation reduces the problem to that of a planar confluence point for which the theory already exists. Expressions relating the two flows are developed and successfully applied to an experimentally observed intersection. It is found that the three-dimensional flow can have an entirely supersonic downstream flow, unlike its two-dimensional counterpart, and that the flows in the two downstream regions need not be parallel.

It is often assumed that the precise initial conditions exert no influence on the downstream flow development of two-dimensional wakes. A brief investigation of the wakes behind four different bodies shows the lasting influence of upstream history in such flows.

Recently attention has been given to the effects of the stream turbulence on the characteristics of the turbulent boundary layers and the turbulent shear flows. For the boundary layers considerable information on the effects of the stream turbulence is available but for the shear flows it is limited. This paper describes an experimental investigation for the effects of stream turbulence on the development of an asymmetric jet and a plane mixing layer. It is shown that the characteristics of these flows are considerably affected by the stream turbulence but for the measurements in the plane mixing layers at large downstream distances the influence of the stream turbulence is negligible provided the intensities are less than 0.6%. For the plane mixing layer the results show that the flow characteristics are not affected significantly by the initial boundary layers, the acoustic disturbances and the boundary conditions imposed by the end plates.

The incompressible planar flow past a wing with a jet issuing from the trailing edge is calculated by two separate methods, both adaptations of conformal mapping routines that are numerically exact in the jet-free case. These are the well-known circle mapping method and the halfplane method. The former is rendered inexact by the jump conditions across the jet and an approximation is necessary. The halfplane method, however, remains exact in principle, and a range of results is presented below. The most accurate of the previous calculations is verified, and comparisons between the halfplane and circle methods are also made. The halfplane scheme seems well suited for such wake-controlled flows and has been extended to transonic conditions in a related study.