Compressible Fluids

Abstract

In further chapters we study machines that function with compressible fluids, first steam turbines (Chap. 6), then gas turbines and compressors (Chaps. 11–15). For analysis of these machines, knowledge of fundamentals of compressible fluid flow is necessary. We study compressible fluid flow in the present chapter, for one-dimensional steady flows. This term indicates a flow whose properties change in a single spatial direction, namely an average streamline, and that is uniform in the spatial directions perpendicular to this streamline and constant in time. The streamline need not be straight. The discussion is limited to what is strictly necessary for fundamental analysis of turbomachines. We justify the use of constant density for a compressible fluid with a limited change of the pressure, as done in the analysis of fans in the previous chapter. We refer to books on fluid mechanics for more in-depth study (Fox et al. in Fox and McDonald’s introduction to fluid mechanics. Wiley, 2019; Gerhart et al. in Munson, Young and Okiishi’s fundamentals of fluid mechanics. Wiley, 2016).