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No description available.

No description available.

No description available.

The object of this work was to design and build equipment to measure the aerodynamic forces which will cause self-induced oscillations of a body having an unsymmetrical cross-section, such as a D-section. This self-induced oscillation has been called "stall flutter" or in electrical transmission lines, "galloping-transmission lines." It is hoped that this equipment will be used to gain basic Information about these aerodynamic forces.

In this thesis a Pascal computer program is presented which calculates a proposed design of parachute from some simple input parameters, of the type specified by a customer to a parachute company. The program reduces by a significant degree time spent by parachute engineers in the preliminary design stages. Parachute design is a process which (in common with much engineering design) can be regarded as consisting of a number of separate calculations. The most suitable method (or methods) for each calculation were selected after a thorough investigation of parachute design techniques. The chosen methods must be sufficiently accurate and readily conform to a computer treatment. The data required by the program have been collected from various sources and are stored in a number of files on a floppy disk. The program is applied to requirements received by a parachute company and results obtained compared with the actual parachutes designed. The program is highly interactive with the user who is able to dispute its selection of values for various parameters. Because the designer can make a rapid and objective choice between a number of methods for various calculations, the existence of this program contributes to his knowledge of the relevance of the parameters involved in, and his understanding of, parachute design. Examples of these techniques are given in the text. Possibilities for expanding and improving the program exist in a number of areas. In some cases the data required for a particular parachute or particular design methods are not available or do not exist. Provision has been made for such data to be included in the program when they are received.

The viscous flow around rectangles defined by afterbody length, B, and cross-stream dimension, A, is investigated through a hybrid discrete vortex method. For uniform flow conditions the effects of varying the side ratio, BIA, the angle of incidence, a, and the Reynolds number, Re, are all considered. Pulsating flow results are reported for rectangular cylinders with B/A values of 0.62, 1.0, 2.0 and 3.0, a B/A=1.0 cylinder inclined at 45° and a circular cylinder. At a fixed Reynolds number, Re=200, the variation of drag coefficient with side ratio shows CD increasing with decreasing B/A. This contrasts with the known result at higher Reynolds number, 104<Re<105, for which a maximum drag occurs close to BIA=0.6. A peak is observed in both the Strouhal number and lift coefficient close to B/A=0.30. This is explained by the afterbody suppression of the shear layer interaction. In the case of the square cylinder, results are presented for the variation of drag coefficient and Strouhal number with Reynolds number, 50<Re5x103. Good agreement with experiment is shown although for Re>500 the calculated Strouhal number is dual valued. The 'lock-in' characteristics under pulsating flow are shown to be highly dependent on body geometry. All the cylinders are shown to exhibit an asymmetric resonant mode within which the shedding frequency is controlled at half the forcing frequency and the mean forces increase. Several different shedding patterns are predicted across this asymmetric synchronisation range. A 'quasi-symmetric' mode is also observed for some cylinders characterised by near wake symmetry and a substantial reduction in mean forces. A pseudo-phase lag is defined which relates a moment of the lift cycle to a moment of the forcing oscillation. This is shown to change across the synchronisation range of each cylinder considered and the change is found to be greater at lower forcing amplitude.

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No description available.

No description available.