Earlier analysis, Middleton, of the laminar discharge of a ‘strong’ incompressible jet, due to a line or point source of momentum, into an unbounded co-flowing stream of the same density, is extended to the case of plane and round ‘weak’ jets the velocity in which only slightly exceeds the ambient velocity. In addition to recovering Goldstein’s solutions for ‘wake-like’ flows, use of the momentum integral equation provides approximate relationships for the decay of the centre velocities from the strong to the weak situations. Comparison is made with Wygnanski’s perturbation approach, suitably extended, and it is concluded that for the plane jet case, for which the agreement is better, the curve for the centre-plane velocity is correct to within about 12% throughout its range. The present approach is applicable to any flow for which a similarity solution exists as a first order solution, and is especially suitable when two such solutions exist for large and small values of an appropriate parameter. Its use also throws light on the form to be adopted for a perturbation expansion.

The fluctuating loading on a cylindrical bluff body due to vortex shedding increases if the body is capable of vibration. This is a result of amplification of the fluctuating pressures around a two-dimensional section of the body together with an improvement of the spanwise correlation of the vortex shedding. Measurement of the fluctuating forces on the cylinder during this process gives no guide as to the relative magnitude of these effects. In this paper, root mean square fluctuating pressure distributions and pressure correlations across a chord are presented for a square cylinder with front face normal to the approach flow whilst stationary and during forced vibration. The fluctuating lift coefficient for a two-dimensional section of the cylinder and its maximum amplification during vibration are calculated.

The influence of spanwise correlation of fluctuating pressures due to vortex shedding on the total oscillatory loading of a long bluff cylinder in cross-flow is considered. Experimentally determined pressure correlation lengths on a stationary and vibrating cylinder of square cross section are then combined with previously obtained chordwise pressure distributions to demonstrate the amplification of the oscillatory lift on a long bluff cylinder during cross-flow vibrations.

The quasi-one-dimensional theory due to Carpenter and Johannesen is applied to supercritical swirling flows in convergent-divergent nozzles. Only flows with uniformly constant stagnation pressure and entropy are considered. Values of exit impulse function and area ratio are given for various types of swirling flow with a range of back-pressure ratios. Thrust coefficients are calculated using these values and specific thrust coefficients plotted against maximum swirl velocity for various cases. In some cases the specific thrust for swirling nozzle flows very slightly exceeds the no-swirl value. The effects of nozzle wall curvature and flight speed on swirling nozzle flows are discussed. The contribution of post-exit thrust to the total thrust is estimated for swirling flow. Finally, the implications are considered of using swirl at the cruise conditions of a typical SST.

A measurement of the pressure distributions on D-section prisms over wide ranges of depth to height ratio and incidence in a smooth and in a turbulent flow was made with particular reference to the onset of transverse galloping. Good correlation between the onset of galloping and the critical depth, established already for rectangular and the related prisms with sharp downstream corners, applied also to D-section prisms both in a smooth and in a turbulent flow. The development of a reattachment type pressure distribution on the side face of the prism as the critical depth is reached is responsible for this correlation. There is very little effect of turbulence on the pressure distribution and the Strouhal number of a D-section prism with a depth to height ratio of 0.5.