The Feasibility of an Euler-Lagrange Approach for the Modelling of Wet Steam

Abstract This study investigates the applicability of an Euler-Lagrange approach for the calculation of nucleation and condensation of steam flows. Supersonic nozzles are used as generic validation cases, as their high expansion rates replicate the flow conditions in real turbines. Experimental and numerical validation data for these nozzles are provided by the International Wet Steam Modelling Project of Starzmann et al. (2018). In contrast to most participants of that project, an Euler-Lagrange approach is utilized for this study. Therefore, the classical nucleation theory with corrections and different droplet growth laws is incorporated into the Discrete Phase Model of ANSYS Fluent. Suggestions for an efficient implementation are presented. The Euler-Lagrange results show a good agreement with the experimental and numerical validation data. The sensitivities of the Euler-Lagrange approach to modelling parameters are analysed. Finally, an optimal parameter set for the calculation of nucleation and condensation is proposed.

Abstract This study investigates the applicability of an Euler–Lagrange approach for the calculation of nucleation and condensation of steam flows. Supersonic nozzles are used as generic validation cases, as their high expansion rates replicate the flow conditions in real turbines. Experimental and numerical validation data for these nozzles are provided by the International Wet Steam Modeling Project of Starzmann et al. (2018, “Results of the International Wet Steam Modeling Project,” Proc. Inst. Mech. Eng. A, 232(5), pp. 550–570). In contrast to most participants of that project, an Euler–Lagrange approach is utilized for this study. Therefore, the classical nucleation theory with corrections and different droplet growth laws is incorporated into the discrete phase model of ansysfluent. Suggestions for an efficient implementation are presented. The Euler–Lagrange results show a good agreement with the experimental and numerical validation data. The sensitivities of the Euler–Lagrange approach to modeling parameters are analyzed. Finally, an optimal parameter set for the calculation of nucleation and condensation is proposed.

This paper describes an investigation into the behaviour of drops which impinge upon dry and wet surfaces. This is of particular interest in the context of the wet steam turbine. Two approaches have been made in the studies; these are: (1) Drops were made to impinge normally on to various types of dry, stationary surfaces. The drops were in the size range 300–1500 μm diameter with velocities of 2–9 m/s. (2) Drops were made to impinge on to surfaces moving with considerable velocity at right angles to the motion of the drop. Surface velocities ranged up to 45 m/s. The latter study is of direct interest for the splashing of drops on turbine casings at small glancing angles, as occurs near drainage belts. Analysis of the mechanisms involved is made from the records of high-speed ciné photography.