Accession Number : AD0673107

Title :   SHOCK TENSORS AND SHOCK POLARS,

Corporate Author : BALLISTIC RESEARCH LABS ABERDEEN PROVING GROUND MD

Personal Author(s) : Bennett,F. D.

Report Date : MAY 1968

Pagination or Media Count : 27

Abstract : A refraction law for the velocity at an oblique shock in a compressible fluid is derived in dyadic form similar to that for refraction of light rays at an interface. The shock tensor embodies only the assumptions of conservation of mass and equality of tangential velocity components. Its eigenvalues and eigenvectors are easily found and interpreted. Given the shock inclination and density ratio, a quadratic equation in the ratio of the flow speeds can be found with flow turning angle as a parameter. Analysis of the two solutions shows that they lie on a circle in the polar plane, a result independent of the equation of state or other conservation laws. If density ratio is allowed to vary, a pencil of circles is generated in the hodograph plane; or, equivalently, a right elliptic cone with two nappes appears in the three-space formed when the density ratio coordinate is added at right angles to the hodograph plane. The further requirements that momentum and energy be conserved taken together with weak restrictions on the functional form of the equation of state are sufficient to permit the development of a general theory of shock polars. The allowed shock states are seen to lie on the space curve formed by intersection of a surface called the Hugoniot cylinder with the elliptic cone. The projection of this space curve on the hodograph plane is the shock polar. The theory is applied to the special case of a polytropic gas by way of illustration. (Author)

Descriptors :   (*SHOCK WAVES, VELOCITY), REFRACTION, MOMENTUM, ENERGY, EQUATIONS OF STATE, SURFACES, THEORY, FLOW VISUALIZATION, COMPRESSIBLE FLOW, THERMODYNAMICS, INVARIANCE

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE