Calculation of Thermodynamic Wetness Loss in Steam Turbines Using CFD Simulation

Abstract

In the paper, the behaviour of wet steam flow is described in three different steam turbines. The first one is the 1100 MW turbine in the nuclear power plant with the pressurized water reactor. The second one is the 660 MW turbine in the fossil fuel power plant with ultra-supercritical steam parameters at the turbine inlet. The last turbine has a nominal output of 34 MW and operates in the municipal waste incinerator. However, this turbine can often also operate even at 2 MW or higher. In all three turbines in the last stage area passages are made for an optical probe to measure steam wetness and primary droplets size, and for a pneumatic probe to determine the pressures, velocities and flow directions. Based on experimentally obtained data analyses of thermodynamic wetness loss for all three turbines are performed using numerical flow simulations considering equilibrium and non-equilibrium steam. The condensation model that includes the nucleation rate and droplet growth velocity used in ANSYS CFX is calibrated based on experimentally obtained data. It is evident that the obtained loss patterns depend fundamentally on the turbine type and operating parameters.