CFD Modeling of Nucleating Steam Flow in a Nozzle Using Inside Plates to Reduce Wetness Fraction

The formation of liquid droplets due to the rapid expansion of steam flow over turbine blades leads to the undesirable erosion of the blades. Thus, anincrease in the wetness fraction leads to an increase in either erosion rate or mechanical losses. Due to the undeniable influence of steam turbines in variousindustries, including steam power plants, it is essential to propose methods to improve their efficiency. In this research, a novel idea is developed todecrease the wetness fraction at a low initial cost. This idea focuses on using a series of flat plates in the divergent section of a two-phase supersonicconvergent-divergent nozzle. Using the wet steam multi-phase model and k-ω SST turbulence model, simulation is conducted using Fluent software. Theeffects of the number of plates in the divergent section of the nozzle on the reduction in the wetness fraction are studied. It is found that, by increasing thenumber of the inside plates, the most reduction in the wetness fraction at the nozzle outlet for the adiabatic condition is achieved, which decreases theerosion rate and condensation losses.

Keywords:

Wetness Fraction , Turbine Efficiency , Wet Steam , Non-Equilibrium Condensation , Blade Erosion