Dense gas effects in a converging-diverging nozzle

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Virginia Tech


Analytical and computational models for the solution of steady inviscid flows in a converging-diverging nozzle are presented for a general fluid. The main emphasis is placed on Bethe-Zel'dovich-Thompson fluids, i.e., those having specific heats so large that the fundamental derivative of gasdynamic is negative over a finite range of pressures and temperatures. Three general classes of flow are delineated which include two nonclassical types in addition to the usual classical flows; the latter are qualitatively similar to those of a perfect gas. The nonclassical flows are characterized by isentropes containing as many as three sonic points. Numerical solutions depicting finite strength expansion shocks, steady flows with shock waves standing upstream of the nozzle throat, and steady flows containing as many as three shock waves are presented. Nonclassical flows having arbitrarily large exit Mach numbers can be obtained only if a sonic expansion shock is formed in the nozzle.