Aerodynamic and thermal characteristics of three-dimensional star-shaped bodies in a rarefied gas

Abstract

The search for shapes of a body optimal with respect to its aerodynamic characteristics has led to the investigation of star-shaped bodies. Numerous theoretical and experimental studies [1–3] have demonstrated the advantages of such bodies compared with the equivalent bodies of revolution for motion in a dense gas in a wide range of supersonic velocities. Since the folded surface of star-shaped bodies appreciably exceeds in area the surface of the compared bodies of revolution, and in a rarefied gas the forces of viscous friction are of the same order as the pressure forces, it is important to investigate whether star-shaped bodies are optimal for flight at hypersonic speeds in rarefied gases at different altitudes. In the present paper, under the assumptions of the “locality hypothesis” [4] expressions are obtained for the main aerodynamic and thermal characteristics of bodies having a front end in the shape of a regular star with n rays joined smoothly to a circular rear end by the method proposed by Gusarov et al. [3]. A detailed analysis of the main characteristics is made and the range of variation of the aspect ratio and the number of rays of the optimal star-shaped configuration are established for different degrees of rarefaction of the atmosphere.