Surface Roughness Effects on Turbine Blade Aerodynamics

Abstract

The aerodynamic performance of a turbine blade was evaluated via total pressure loss measurements on a linear cascade. The Reynolds number was varied from 600,000 to 1,200,000 to capture the operating regime for heavy-duty gas turbines. Four different types of surface roughness on the same profile were tested in the High Speed Cascade Wind Tunnel of the University of the German Armed Forces Munich and evaluated against a hydraulically smooth reference blade. The ratios of surface roughness to chord length for the test blade surfaces are in the range of Ra/c = 7.6×10−06 – 7.9×10−05. The total pressure losses were evaluated from wake traverse measurements. The loss increase due to surface roughness was found to increase with increasing Reynolds number. For the maximum tested Reynolds number of Re = 1,200,000 the increase in total pressure loss for the highest analysed surface roughness value of Ra = 11.8 μm was found to be 40% compared to a hydraulically smooth surface. The results of the measurements were compared to a correlation from literature as well as to well-documented measurements in literature. Good agreement was found for high Reynolds numbers between the correlation and the test results presented in this paper and the data available from literature.

On the role of surface roughness in the aerodynamic performance and energy conversion of horizontal wind turbine blades: a review

“…Third, an experimental test was presented by Hummel et al [28] to evaluate the aerodynamic performance of a rough blade surface. Four different heights of surface roughness were added for a Reynolds number range from 60 × 10 4 to 120 × 10 4 .…”

Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

“…The association of wake velocity deficits with the aerodynamic losses caused by smooth and the roughened airfoils is discussed by a number of investigations, such as Bammert and Sandstede [19,20], Kind et al [21], Bogard et al [22], Abuaf et al [23], and Leipold et al [24]. More recently, Hummel et al [25] and Boyle and Senyitko [26] have presented important wake total pressure loss data to provide information of the effects of surface roughness effect over a range of Reynolds numbers.…”

The Effects of Different Roughness Configurations on Aerodynamic Performance of Wind Turbine Airfoil and Blade

“…Effects of various , roughness height and roughness shape in a dusty condition experimentally tested by Hummel et al (2005). They showed that increment of increases total pressure losses.…”