Exact and Approximate Equations for Real-Fluid Isentropic Flow

Abstract

Two sets of exact isentropic-flow equations are developed, corresponding respectively to the Tait-Kirkwood equation (P + B) vkT = constant and to the Laplace-Poisson equation PvkL = constant. The exact real-fluid equations have the form of conventional perfect-gas equations, with additional correction terms which are usually small. Similarity principles for each set of equations are given, the Laplace-Poisson form being new. Various simplified forms of the exact equations, of the kind used in practice, are tested for accuracy in an example.