NUMERICAL-SOLUTIONS OF 2-DIMENSIONAL MULTISTAGE ROTOR/STATOR UNSTEADY-FLOW INTERACTIONS

A two-dimensional, Navier-Stokes, multizone approach has been used to investigate unsteady now interactions within two multistage axial turbines. The governing equations are solved by an iterative, factored, implicit finite difference, upwind algorithm. For the numerical accuracy check, investigations are also carried out on the effect of temporal accuracy, the effect of subiteration in the Newton-Raphson technique, and the effect of full viscous vs thin-layer calculation. Computed results of a one and one-half-stage calculation compare well with experimental data. Unsteady flow interactions, wake cutting, and the associated evolution of vortical entities are discussed. Computed results of a six-stage calculation also compare well with engine balanced data obtained from a classical one-dimensional analysis. The calculated transient accurate solutions provide much information for component analysis, especially for computing the forcing function used in a structural dynamic analysis.