Investigation of pitch variation on wet steam flow parameters in a turbine blade cascade

The presence of the liquid phase in the last stage of the steam turbine leads to thermodynamic and mechanical losses. This paper presents an investigation of the pitch to chord variation to reduce the liquid phase at the exit of the cascade turbine blade in wet steam flow. In this regard, the genetic algorithm is utilized to find optimum pitch to chord. The wetness fraction (WF), droplet size (DS), number of droplets (ND) and erosion rate (ER) are the objectives of this study. The calculations were conducted by employing ۲D compressible Reynolds-averaged Navier-Stokes (RANS) equations, and the Eulerian-Eulerian approach are employed for modeling condensing flow. The agreement obtained between the numerical and experimental results is satisfactory. The results show that a pitch to chord ratio of Pi/AC=۰.۷۶ is the suitable case. In this case compare to original case, the wetness fraction, droplet size, and erosion rate are reduced ۳.۵۹%, ۱.۹۴%, and ۱۰.۲۵% respectively

Keywords:

pitch variation , wetness fraction , droplet size , number of droplets , erosion rate