A Comparison of Numerical Solutions of the Unsteady Flow Equations Applied to Reciprocating Compressor Systems

Abstract

The paper reviews briefly a number of methods which are now available to facilitate solutions to the hyperbolic partial differential equations describing unsteady compressible fluid flow. Various schemes are considered and their merits and disadvantages discussed. Equations describing unsteady one-dimensional flow with heat transfer, area change and friction are presented in conservation-law, normal and characteristic forms. Pulsations in a compressor system are predicted using both the two-step Lax-Wendroff scheme and a scheme based on the characteristic form of the equations. The Lax-Wendroff scheme was simpler to apply, required less computer time, and gave better agreement with experimental results obtained from a single-stage reciprocating air-compressor system.