A numerical study of two-phase transonic steam flow through convergence-divergence nozzles with different rates of expansion

Abstract

During transonic flow of steam in divergence nozzles, flow first supercools and then nucleates to become two-phase droplet flow. This phenomenon especially occurs in the last stages of steam turbines and affects performance. In this research, a numerical scheme for two-phase flow in nozzle passages is developed. An Eulerian-Eulerian reference frame is used for both phases. The shear stress transport turbulence model is used to model the Reynolds stresses appearing in the averaged Navier-Stokes equations. The homogeneous nucleation model is applied for the mass transfer in the transonic conditions. In this paper three nozzles with different rate of expansion are employed to be under study. Overall pressure ratio (static to total pressure) and droplet size are compared with the experimental data and good agreements are observed.

CFD modeling of condensation process of water vapor in supersonic flows

“…Yang & Sheng [20] described a conservative two-dimensional compressible numerical model for the non-equilibrium condensing of the steam flow based on the classical nucleation theory and the Virial type equation of state. The effect of the expansion rate on the steam condensing flow through a converging-diverging nozzle was studied numerically by Nikkhahi et al [21]. The steam condensing flow was modeled through the Laval nozzles at low and high inlet pressures by means of the single-fluid model [22].…”

Numerical Simulation on Condensing Flow of Water Vapor of Wet Natural Gas Inside the Nozzle

“…Some researches (Xiao et al, 2007;Yang et al, 2009) described a conservative twodimensional compressible numerical model for the non-equilibrium condensing of the steam flow based on the classical nucleation theory and the Virial-equation of state. The effect of the expansion rate on the steam condensing flow through a converging-diverging nozzle was studied numerically (Nikkhahi et al, 2010). The steam condensing flow was modeled through the Laval nozzles at low and high inlet pressures by means of the single-fluid model (Mahpeykar et al, 2011;Shooshtari et al, 2013;Dykas et al, 2011).…”