A mathematical model of homogeneous and heterogeneous condensation in the turbomachinery is presented. The mathematical model consists of conservation laws of mass, momentum, energy and conservation laws for the description of the rise and growth of water droplets with the homogeneous
and heterogeneous condensation. The relaxation method is introduced for solving the two-dimensional unsteady
flow through the turbine cascades. The method is developed for unstructured grids
and is applied to the flow in the Laval nozzle.