The stability of a two-dimensional wall jet was studied theoretically and experimentally. As a result of the linear stability calculation, it was found that one eigenmode is separated into two modes when the Reynolds number is large, and inside a neutral stable curve in the α, R-plane there exists another neutral curve enclosing a stable region. Experimental results of small disturbances were compared with calculated results; agreement between them was satisfactory. It was found, further, that subharmonics of a predominant disturbance velocity component appear in the non-linear region.

Measured stability characteristics in a radial wall jet were compared with calculated results for a two-dimensional wall jet. It was found that the stability of the radial wall jet is similar in many respects to that of the two-dimensional wall jet. An exception is that the local amplification rate of the disturbance velocity is much higher than in the two-dimensional case. It was also found that quarter-harmonics appear in the non-linear region, as well as half-harmonics, and that their amplitude distributions show profiles similar to that of the fundamental component. Further, vortex patterns were visualised in water flow, and results corresponding to measurements in air flow and to the linear stability calculation were obtained.

The paper suggests a simple method of generating intermittent reservoir conditions for an intermittent, cryogenic wind tunnel. Approximate performance estimates are given and it is recommended that further studies be made because this type of tunnel could be valuable in increasing the opportunities for research at high Reynolds numbers.

Based on computing efficiency, a comparison is made of three different ways of representing the chordwise variation of bound vorticity for use in panel methods. Because of expense, the two-dimensional analogues of the three-dimensional models were used and the results assumed to hold in both situations. A constant panel of vorticity is found to have inherent difficulties which make it unattractive to use. A linearly varying vorticity model is found to be best but a model using line vortices is almost as good and, moreover, simpler to use.

If a canopy is idealised as a cylinder with one end open to the free-stream flow, and the other end closed, then the internal flow during inflation is given by a simple analytic function. In this note the function is derived and then the internal pressures and corresponding forces associated with inflation are determined. It is found that, in addition to ram pressure and the von Kármán “virtual mass” terms in the pressure equations, there are other transient terms associated with radial velocity and acceleration.

This paper describes four techniques that can be applied to predict the response of an aircraft (including STOL and VTOL vehicles) to wind shear and turbulence during the landing approach. A comparison among the techniques is carried out by predicting the longitudinal response of a light STOL transport to atmospheric conditions within the earth’s planetary boundary layer. The turbulence data were generated by a boundary-layer wind tunnel and by an instrumented helicopter. Of the four techniques described, the flight path correlation technique is the most recent, having been developed to handle some of the problems facing the analysis of STOL and VTOL aircraft response. The other three approaches are the power spectral density technique, the equivalent deterministic input technique, and the in-flight turbulence measurement technique. The practical features of each of these are outlined and typical response predictions are plotted as a function of height during the landing approach. In general terms it was concluded that the techniques requiring the greatest amount of data-collection sophistication and computation (the in-flight data measurement and flight path correlation techniques) would produce the best results.

The flow field produced by the intersection of two plane solid surfaces in a supersonic stream is a complex interference flow. These flows can be fully compressive, fully expansive or of mixed compression-expansion nature. This paper presents a comparison of the flow field structure in an axial corner obtained experimentally with that predicted numerically by using a shock-capturing finite-difference method. The effect of sweep and surface deflection are evaluated and the general influence of each is presented for the three classes of corner flows. The results of this study show that the numerical method is a valuable aid in understanding the flow structure for simple configurations. In addition confidence in the numerical method is gained for use in solving the more general three-dimensional configurations where the flow is non-conical and several wave interactions may be present.