Water Droplets Dispersion and Optimization of Water Removal Suction Slot Locations on Stationary Blades in Last-Stage of a 600 MW Steam Turbine

Abstract

Water droplets dispersion through a stationary cascade channel and their deposition on the blade surface in the last-stage of a 600MW steam turbine have been simulated with CFD software FLUENT. So the deposition on stationary blades along the axial and radial direction was determined. In the experiment, the performance of water removal by suction slots on stationary blades surface was investigated. The results showed that: 12.2% of water at the inlet still existed as droplets, depositing on the concave side of the airfoils in contrast with only 1.6% on the convex side. The volume of the water removed by the suction slots on the concave side was bigger than that on the convex side. The closer the slot position was to the trailing edge, the bigger the volume was. The volume became smaller and then larger with the increase in slot width; the minimum value occurred when slots were about 3.0 mm in width. The bigger suction pressure difference would initiate a bigger volume of water removed by suction slots, but the increase in main flow rate would quickly initiate a smaller volume.

Steam turbine flow path drainage system under different operating conditions

“…Many authors are engaged in experimental research of the steam mixture flow near the suction grooves. The dimensions, shapes and locations of the grooves on the surface of stator blades are verified with regard to maximum efficiency of the water film suction with minimal amount of steam sucked from the flow part [6,7]. The results of experimental and analytical studies are valuable which assume that the water film on the surface of stator blades is not sucked, but on the contrary, that the inside of the hollow blade is heated by warmer steam and the water film evaporates [8,9].…”

Numerical and experimental study of droplet-film-interaction for low pressure steam turbine erosion protection applications

“…Particularly the application of extraction / suction slots has been in focus of numerical and experimental investigations in the last decades. (Wang et al, 2009;Gribin et al, 2015;Li et al, 2018;Hoznedl et al, 2019).…”

Numerical and Experimental Study of Droplet-Film-Interaction for Low Pressure Steam Turbine Erosion Protection Applications

“…(3) Braking losses are generated by large droplets which impinge on the surfaces of moving blades and thus reduce the amount of work. (Gyarmathy, 1962;Kreitmeier et al, 2005;Kawagishi et al, 2013;Starzmann et al, 2014;Wu et al, 2017) The phenomenon of water droplet erosion is usually described with successively occurring phases. Tiny droplets are created as the sub-cooled steam returns to a state of equilibrium (homogenous nucleation).…”

“…Particularly the application of extraction / suction slots has been in focus of numerical and experimental investigations in the last decades. (Wang et al, 2009;Gribin et al, 2015;Li et al, 2018;Hoznedl et al, 2019) Passive measures however aim at increasing the erosion resistance of the blading by either applying better materials with increased hardness (Lee et al, 2003), flame/laser hardening of leading edges (Schuerhoff et al, 2015;Yao et al, 2010) or by shielding the affected areas with materials such as stellite. Also the application of coatings either for protection or for fog rejection purposes is investigated (Walsh et al, 1993;Buehlmann et al, 2018).…”