Prediction of Surface Roughness and Incidence Effects on Turbine Performance

Abstract

The use of a Navier-Stokes analysis to predict the change in turbine efficiency resulting from changes in blade surface roughness or incidence flow angles is discussed. The results of a midspan Navier-Stokes analysis are combined with those from a quasi-three-dimensional flow analysis code to predict turbine performance. A quasi-three-dimensional flow analysis code was used to determine turbine performance over a range of incidence flow angles. This analysis was done for a number of incidence loss models. The change in loss due to changes in incidence flows computed from the Navier-Stokes analysis is compared with the results obtained using the empirical loss models. The Navier-Stokes analysis was also used to determine the effects of surface roughness using a mixing length turbulence model, which incorporated the roughness height. The validity of the approach used was verified by comparisons with experimental data for a turbine with both smooth and rough blades tested over a wide range of blade incidence flow angles.

The Effect of Adding Roughness and Thickness to a Transonic Axial Compressor Rotor

“…The additional mixing length is a function of the equivalent sand grain roughness height, which is fairly small for the roughness considered here. The addition of this model to the code has been discussed in detail by Boyle and Civinskas (1991) and Boyle (1993).…”

“…The effects of roughness on turbine aerodynamic performance have been investigated experimentally by Roelke and Haas (1982) and Boynton et al (1992). Boyle (1993) recently predicted the efficiency loss due to roughness measured by Boynton by using a quasi-3D Navier-Stokes analysis in which he augmented a mixing length model to account for the effects of surface roughness. The effect of roughness on compressor blade aerodynamic performance was reported by Moses and Serovy (1951), who documented the performance changes which resulted from polishing an initially rough blade.…”

Gas turbine upgrading and renovation with respect to pollution and degradation

“…Increased surface roughness causes thicker boundary layers on the blades and stationary components, and thus may reduce the flow capacity. Efficiency losses of 2.5 per cent for a 10.2 μm surface roughness when compared with smooth blades were reported for a turbine [18]. Combustor degradation is very complex to study.…”

Método para optimizar la planificación de los lavados “off-line” en compresores de turbinas de gas

“…Sus estudios revelan el cambio de los ángulos de los álabes. También Boyle (1994), Kind et al (1996) y Bons (2010) hacen énfasis en el incremento de rugosidad debido al deterioro. Boelcs and Sari (1988) concluyeron que un álabe bien diseñado no modifica sus propiedades de flujo significativamente aunque exista suciedad en su cara de presión.…”