Analysis and testing have been used to develop a flapping wing which can efficiently produce lift and thrust for ornithopter flight. With the assumption that the only imposed motion is dihedral flapping at its root, the wing's spanwise distribution of pitching and bending is due to its aeroelastic response. Numerical studies revealed criteria for efficient designs, which then guided the development and construction of an example wing tested in a windtunnel. The experimental results for average thrust and lift compared very favourably with the theoretical predictions, confirming that such aeroelastically tailored designs provide a means for achieving mechanical flapping-wing flight.

Transonic shockwave/turbulent boundary layer interactions on a porous surface above a closed plenum chamber have been studied experimentally in the choked flow of a windtunnel test-section. The equivalent freestream Mach number is 0.76 and results were obtained for three shock strengths. Without the porous surface the Mach numbers ahead of the shock were 1.13, 1.18 and 1.26. The respective shock Mach numbers with the porous surface were 1.10, 1.11 and 1.19. Laser holographic interferometry results are used to measure the density flowfield and examine the nature of the interaction. These results show that the interaction on the porous surface is modified by a thin shear layer adjacent to the surface and the weakening of the Shockwave is attributed to this. The interaction was also studied by solving the two-dimensional Reynolds-averaged Navier-Stokes equations together with the two-layer algebraic eddy-viscosity model of Baldwin-Lomax modified with appropriate corrections for surface transpiration. The computed results show excellent agreement with the experimental data. The examination of these numerical results shows that the surface transpiration occurs at a low subsonic velocity and suggests that the effect of the transpiration through the porous surface on the interaction may be optimised.

Experiments to study the behaviour of a compressible free jet issuing from an axisymmetric convergent nozzle are reported. Detailed measurements of the mean flow field for subsonic, sonic and underexpanded sonic jets was made within the pressure ratio range of 1.13 to 4. The results show that the spread and decay rates of the jet vary significantly with pressure ratio. The results further indicate the radial velocity/total pressure collapse within the two-dimensional shear layer data. The underexpanded jet propagates to a greater distance downstream than the low speed jets; this leads to enhancement of the far field mixing.

After showing the extension of one-dimensional duct-flow equations to flows in which total pressure is lost from one station to another, it is shown how a pitot static traverse at a general station can be used to measure the drag developed upstream of that station. This was the first section of Ref. 1.