Time-marching method for the prediction of two-dimensional, unsteadyflows of condensing steam

A time-accurate, two-dimensional time-marching technique is presented which can predict unsteady phenomena in condensing steam flows. Conservation equations for the mixture are solved using a variation of a well-established Euler solver, while nucleation and droplet growth calculations are performed in a Lagrangian framework by tracking particle pathlines. A special averaging technique is used to retain a polydispersion of droplet sizes, necessary for the accurate modeling of the condensation processes, without consuming excessive storage or CPU time. The basic Euler solution technique has been validated by comparison with predictions from an independent source for the unsteady flow of air in a channel. The full scheme has been used to compute nucleating flows in converging-diverging nozzles for which agreement with experiment for both steady and unsteady cases is extremely good. All the results presented are for flows in nozzles for which experimental data are available, but the scheme may also be applied to turbine cascade geometries. 26 refs.