In a supersonic flow of pure vapour in adiabatic diffusers, under some circumstances, nucleation phenomenon occurs and consequently vapour condensation is observed. In this process, the resulted pressure rise is called the condensation shock which causes undesirable instabilities, sudden changes in the steam flow and increase in the entropy generation On the other hand, the formed droplets grow which could hardly strike the channel’s walls and make some serious damages; therefore, it is necessary to control the sudden pressure rise. The innovation of this research is analytically modeling the volumetric heat addition to the steam flow in a convergent-divergent supersonic nozzle. This method develops a solution for reducing the nucleation and condensation rates which results in increasing exergy or reducing the entropy generation The analysis of the results shows that an appropriate volumetric heat addition to the convergent section of a convergent-divergent supersonic nozzle can reduce the degree of supercooling and subsequently reduce the nucleation rates significantly. The condensation reduction declines the irreversible internal heat transfer which improves the efficiency of the steam flow and reduces the losses including the mechanical damages tremendously.

Keywords