Two methods of analysis are developed for the unsteady wave flow through axial turbomachinery of high hub-tip ratio. In the first method, the machine is supposed to consist of an infinite number of small stages. Differential equations for the instantaneous values of flow properties are derived which may be solved directly or by the method of characteristics. Conditions for wave propagation are discussed. Secondly, a model is used in which actuator discs replace the stages and the flow is axial between the stages. This is a good approximation in many compressors in which the leaving angle from the stators is small. Again the method of characteristics may then be used for solving the equations of unsteady flow between the discs.

This paper presents results of an investigation of the wake flow of a series of two-dimensional bluff bodies with different boundary-layer separation angles. These results are compared with the results of an earlier investigation of a similar series of axisymmetric bodies. It is found that when the same length scales characterising the wakes that were proposed for the axisymmetric case are used in the current investigation, then there is good agreement between the two cases in the variation of the length scales with boundary-layer separation angle. The universal Strouhal number previously proposed for axisymmetric bodies is derived for the two-dimensional bodies under investigation and is found to remain a constant for the different bodies, but at a different numerical value from that found for the axisymmetric bodies.

An algorithm is described for solving the partial differential equations governing inviscid, incompressible, irrotational and axisymmetric flow in order to obtain duct wall shapes from prescribed wall velocity distributions. Equations of motion are formulated with distances from and along the axis of symmetry as dependent variables. A velocity potential and Stokes stream function are employed as independent variables. A numerical method based on the iterative solution of finite-difference equations on a non-uniform mesh is presented. The residuals obtained from calculations with differing mesh sizes, for the two examples described, indicate that the proposed method gives satisfactory solutions to the specified design problem.

Following a brief introduction, an examination is presented of the factors which define fracture toughness, resistance-curve relationships and the extent of stable crack extension in thin-sheet failure. Tests have been performed on three aluminium alloys to establish the variations in the shape of resistance curves, using both compliance-indicated and measured absolute values of crack length in compact tension specimens and centre crack sheets. The results show that both the toughness and the resistance curves of the two specimen types are different and that these differences cannot be explained wholly by consideration of crack tip plastic zone sizes.

An improved technique for the use of a five-hole yaw probe has been used in determining velocity, vorticity and pressure distributions over a transverse plane five chords downstream of a lifting wing. A well-defined tip vortex is shown to exist, together with a vortex sheet which contains a significant proportion of the total vorticity. The vorticity distribution is compared with that predicted by the calculation of vortex sheet roll-up using a two-dimensional array of line vortices. Good agreement is obtained, and the validity of using time steps large enough to inhibit the chaotic motion found in some calculations of this type is demonstrated. The structure of the tip vortex is found to be well described by the turbulent vortex model of Hoffman and Joubert.

Wind-tunnel experiments were conducted to determine the interference characteristics of an inclined turbulent jet exhausting from a flat plate into a turbulent subsonic crosswind. The jet was not yawed with respect to the undisturbed free stream. The suction force (lift loss), the jet penetration into the crosswind, the jet deflection and the rate of total pressure decay along the jet centre line were all reduced by an increase in the inclination of the jet. The centre of pressure moved downstream. These results were attributed to a decrease in the entrainment rate of the jet as the inclination increased in a downstream direction.

A series of advanced aerofoil sections suitable for aircraft propellers has been developed. The sections combine advanced supercritical now characteristics with good low-speed performance and are also directly applicable to other rotating aerodynamic machinery, such as low-solidity ducted fans, windmills, etc. The work has focused initially on propeller sections of around 6 per cent thickness/chord ratio, typical of the fundamental blade station where peak loading is usually carried (0.7 × radius). The complete section family covers a wide range of thickness/chord ratios, from 3 per cent to over 20 per cent. The profiles are defined by mathematical formulae and distort with thickness to achieve a shape having optimum performance characteristics at the flow conditions expected for that thickness. A subset of the family is defined for higher Mach number penetration, up to near sonic values. Practical applications of the new sections have shown notable gains.