Numéro : 1940 - Year : 1983
Propulsion by means of an annular swimming flexible surface
G.COULMY, Maître de Recherche au CNRS (LIMSI)
A.ZERVOS, Maître- Assistant à l'Ecole Nationale Supérieure Technique d'Athènes
T.S. LUU, Directeur de Recherche au CNRS ( LIMSI )
In this study, it is shown that it is possible to create a propulsion when the motion of a swimming surface is imposed. Such systems, as they work, induce necessarily a free vortex sheet which may be identified with the surface generated by the trailing edge, as long as the system is not overloaded. In order to respect at any moment the actual form of the swimming surfaces, the problem is solved by means of the singularity method, which appears to be particularly convenient because the thin surfaces of the propulsion device as also the free vortex sheet may be represented by normal axis doublet distributions. This method permits to calculate the real hydrodynamic performances of a given system and to analyse the structure of the flow. The case of an annular surface, in which the wavy motion is caracterized by a progressively increasing amplitude from the upstream to the downstream, is treated. By studying systematically the influence of the various parameters of definition, the optimal propulsion for a given average propulsive thrust is obtained.
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