Prediction of Surface Roughness and Incidence Effects on Turbine Performance

Boyle, R. J.

doi:10.1115/1.2929468

Cited by 40 publications

(20 citation statements)

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Suder

Chima

Strazisar

et al. 1995

Journal of Turbomachinery

129

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The performance deterioration of a high-speed axial compressor rotor due to surface roughness and airfoil thickness variations is reported. A 0.025 mm (0.001 in.) thick rough coating with a surface finish of 2.54–3.18 rms μm (100–125 rms μin.) is applied to the pressure and suction surface of the rotor blades. Coating both surfaces increases the leading edge thickness by 10 percent at the hub and 20 percent at the tip. Application of this coating results in a loss in efficiency of 6 points and a 9 percent reduction in the pressure ratio across the rotor at an operating condition near the design point. To separate the effects of thickness and roughness, a smooth coating of equal thickness is also applied to the blade. The smooth coating surface finish is 0.254–0.508 rms μm (10–20 rms μin.), compared to the bare metal blade surface finish of 0.508 rms pm (20 rms μin.). The smooth coating results in approximately half of the performance deterioration found from the rough coating. Both coatings are then applied to different portions of the blade surface to determine which portions of the airfoil are most sensitive to thickness/roughness variations. Aerodynamic performance measurements are presented for a number of coating configurations at 60, 80, and 100 percent of design speed. The results indicate that thickness/roughness over the first 2 percent of blade chord accounts for virtually all of the observed performance degradation for the smooth coating, compared to about 70 percent of the observed performance degradation for the rough coating. The performance deterioration is investigated in more detail at design speed using laser anemometer measurements as well as predictions generated by a quasi-three-dimensional Navier–Stokes flow solver, which includes a surface roughness model. Measurements and analysis are performed on the baseline blade and the full-coverage smooth and rough coatings. The results indicate that adding roughness at the blade leading edge causes a thickening of the blade boundary layers. The interaction between the rotor passage shock and the thickened suction surface boundary layer then results in an increase in blockage, which reduces the diffusion level in the rear half of the blade passage, thus reducing the aerodynamic performance of the rotor.

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Section: Introductionmentioning

confidence: 99%

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

Suder

Chima

Strazisar

et al. 1995

Journal of Turbomachinery

129

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“…Then, Boyle [8] studied changes in the efficiency of a two stage turbine using Navier-Stokes analysis for a range of incident flow angles and blade surface roughness heights. He combined the results of mid-span Navier-Stokes analysis with a quasi-three-dimensional analysis code to predict turbine performance.…”

Section: Numerical Researchesmentioning

confidence: 99%

Development of a Numerical Based Correlation for Performance Losses due to Surface Roughness in Axial Turbines

et al. 2014

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In the present work, a recently developed in-house 2D CFD code is used to study the effect of gas turbine stator blade roughness on various performance parameters of a two-dimensional blade cascade. The 2D CFD model is based on a high resolution flux difference splitting scheme of Roe (1981). The Reynolds Averaged Navier-Stokes (RANS) equations are closed using the zero-equation turbulence model of Baldwin-Lomax (1978) and two-equation Shear Stress Transport (SST) turbulence model. For the smooth blade, results are compared with experimental data to validate the model. Finally, a correlation between roughness Reynolds number and loss coefficient for both turbulence models is presented and tested for three other roughness heights. The results of 2D turbine blade cascades can be used for one-dimensional models such as mean line analysis or quasi-three-dimensional models e.g. streamline curvature method.

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“…Especially the turbine nozzles, operating at or near choked conditions, are very sensitive to changes in flow area. Increased surface roughness causes thicker boundary layers on the blades and sidewalls, and thus may reduce the flow capacity, especially near choking conditions (Boyle, 1994).…”

Section: Degradation Of Componentsmentioning

confidence: 99%