Numerical investigation of condensing flow in the last stage of low-pressure nuclear steam turbine

Abstract

In this work, the numerical simulation of condensing flow through the last stage of nuclear steam turbine with 1828mm long moving blades and wetness fraction in front of the last stage up to 13% is presented. Equilibrium condensation model and homogeneous non-equilibrium condensation model are employed to calculate the wet steam flow field. The non-equilibrium condensing flow is modeled on the basis of classical nucleation theory. The predicted Markov loss coefficients, stage enthalpy drop, wetness fraction, etc., of wet-steam flow obtained through equilibrium condensing model show discernable differences from those obtained through non-equilibrium condensing model, which results from the secondary nucleation. In addition, the upstream droplets diameter has, to some extent, impact on the non-equilibrium condensing flow with fixed upstream wetness fraction.