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.
Numerical prediction of three-dimensional flow and heat transfer of air and steam are presented for serpentine cooling channels by using the commercial software CFX. The results show that SSG model is the best turbulence model for the ribbed channels. A study of Grid Generation was performed for flow and heat transfer in serpentine cooling channels, with the same turbulence model. And the results show that the space between the first node and the wall surface (Δy) is 0.0001 mm and the grid density is 1.3 or Δy of 0.001 mm and grid density of 1.2 is the appropriate choice for grid generation. Ribbed channels are not sensitive to mesh generation compared with smooth passages. With the same inlet flux, steam heat transfer efficiency is higher than that of air about 15–20%; steam superheat degree is not the key factor for heat transfer, but it had an effect on flow resistance. Compared with smooth channels, ribbed channels reduce the impact of the turn; the best heat transfer regions appear downstream of the turn. V-type ribs have better heat transfer performance than the parallel type ribs; the highest heat transfer occurs in the section between the ribs.
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