Abstract
Background. The efficiency of the steady subsonic motion of vehicles and animals in air and water is estimated with the use of different drag coefficients, the drag-to-weight and power-to-weight ratios.Objective. The improvement of these characteristics with the use of special shaped hulls and wing profiles which remove boundary layer separation and with the use of the supercavitating flow pattern for the high-speed motion in water.Methods. Analytical and numerical estimations with the use of known results for flow on slender unseparated body of revolution and airfoil and for the steady supercavitating flow pattern.Results. Simple analytic formulae were obtained for the movement efficiency, the critical Reynolds numbers of the laminar-to-turbulent transition etc. and applied for different terrestrial, aquatic and airborne vehicles, animals and human sport activity. In a rather large range of the Reynolds number \[10^{6}\leqslant \textrm{Re}_{V}\leqslant 10^{8},\] the use of unseparated shapes yields very substantial reduction of the drag in comparison with the conventional bodies of revolution. In water at \[\textrm{Re}_{V}> 10^{7}\] the supercavitating flow pattern can be preferable.Conclusions. This drag reduction opens up prospects for designing different kinds of very effective airborne and high-speed underwater vehicles.
Highlights
Modern technologies open new horizons for vehicles allowing substantially increase their speed as well as to increase or to reduce their size
During last 20 years the possibility of achieving an attached flow on a rigid body has been investigated in the Institute of Hydromechanics (IHM) of National Academy of Sciences, Kyiv, Ukraine
In this paper we evaluate the effectiveness of the movement in air and water with the use of such criteria as drag coefficients, drag-to-weight and power-to-weight ratios
Summary
ReV 107 the supercavitating flow pattern can be preferable. Conclusions.
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More From: Research Bulletin of the National Technical University of Ukraine "Kyiv Polytechnic Institute"
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