Numerical Study of Reynolds Number Effects on Steam Turbine Performance

Abstract

The performance of blade profiles was examined with three linear cascade blades which represent hub, mid-span and tip section using numerical analysis. The Reynolds number was varied from 10,000 to 10,000,000 to capture the operating regime for typical steam turbines. Twelve different levels of surface roughness on the same profile were calculated using the roughness model in ANSYS-CFX. The ratios of surface roughness to chord length are in the range of ks/c = 4.2 × 10–5 ∼ 8.3 × 10−4. The CFD result was compared to Reynolds number correction curves from published literature (AMDC-KO, Aungier, Craig & Cox, Traupel, Sanders and Denton) and available measurement data. Based on these comparisons, a Reynolds number correction curve was properly selected for the estimation of steam turbine performance. Also, it was found that Reynolds number with hydraulically smooth surfaces has little influence on the change in flow angle and roughness does not significantly change outlet flow angle.