 In order to improve the efficiency of drain separation for the purpose of reducing erosion, it is important to grasp the behavior of micro scale droplets through the LP-end that dominates the water film flow rate on the blade surface. In this paper, the results of inlet/outlet wetness measurement at the final stage of the scaled steam turbine and three-dimensional analysis of water droplet behavior on them are reported.  
 This scaled steam turbine consists of the three stage LP-end and the inlet steam conditioning stage (total four stages), wetness and droplet diameter distribution in the blade height-wise were measured under several operating conditions.  
 Under the design point condition, the diameter of water droplet at the inlet of the final stage was about 1.3 micro-meter, and the water droplet diameter distribution showed a flat in the blade height wise.  
 First, the details of measurement method and measurement values of the flow pattern and the wetness distribution at the final stage are presented. The predicted flow pattern and wetness by the Eulerian Lagrangian coupling unsteady solver were in good agreement with the measured values.  
 Next, the distribution forming mechanism of the wetness at the final stage is discussed from the viewpoint of water droplet inertia and moisture removal by the upstream blade rows.The wetness distribution cannot be reproduced by the Eulerian scheme considering non-equilibrium condensation, but can be reproduced by Euler-Lagrange simulation of water droplets considering clocking of the stator blades and moisture probe. The wetness distribution could not be reproduced by the Eulerian scheme considering non-equilibrium condensation, but could be reproduced by Euler-Lagrange simulation considering clocking of the stator blades and moisture probe.  
 Finally, the mechanism of moisture separation in the LP-end will be comprehensively discussed based on continuous analysis of the collection of fine droplets by the wall, the transfer of water film, and the transfer of coarse water droplets. Under a wide range of temperature conditions, changes in water droplet collection rate by each wall are organized and discussed.


Wetness Measurement and Droplet Transport Analysis in Actual Steam Test on a Scaled Low Pressure Turbine

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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