...Heechan Jeong; Seung Jin Song Effects of low incoming freestream turbulence level (Tu < 1%) and surface roughness on the transition of flat-plate boundary layers under a high-lift airfoil pressure gradient have been investigated. Time-resolved streamwise and wall-normal velocity fields...

...Massimiliano Nardini; Melissa Kozul; Thomas O. Jelly; Richard D. Sandberg High-fidelity simulation of transitional and turbulent flows over multi-scale surface roughness presents several challenges. For instance, the complex and irregular geometrical nature of surface roughness makes it impractical...

...Massimiliano Nardini; Thomas O. Jelly; Melissa Kozul; Richard D. Sandberg; Paul Vitt; Greg Sluyter Turbine blades generally present surface roughness introduced in the manufacturing process or caused by in-service degradation, which can have a significant impact on aero-thermal performance...

... have a range of cooling feature sizes and, because of the inherent three-dimensionality, a wide range of build angles. Previous studies have shown that AM built directions influence internal channel surface roughness that, in turn, augment heat transfer and pressure loss. This study investigates...

...M. Lorenz; A. Schulz; H.-J. Bauer The present experimental study is part of a comprehensive analysis accounting for heat transfer and aerodynamic losses on a highly loaded low pressure turbine blade with varying surface roughness. Whereas Part I focuses on heat transfer measurements at airfoil...

...M. Lorenz; A. Schulz; H.-J. Bauer The present experimental study is part of a comprehensive heat transfer analysis on a highly loaded low pressure turbine blade and endwall with varying surface roughness. Whereas a former paper ( Lorenz et al., 2009, “An Experimental Study of Airfoil and Endwall...

...J. P. Bons The effects of surface roughness on gas turbine performance are reviewed based on publications in the open literature over the past 60 years. Empirical roughness correlations routinely employed for drag and heat transfer estimates are summarized and found wanting. No single correlation...

...R. J. Boyle; M. Stripf Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consistent with smooth vane heat transfer, the transition moves forward...

... calculations on both the suction and the pressure side of modern turbine airfoils. Test cases include extensive experimental investigations on a high-pressure turbine vane with varying surface roughness and turbulence intensity, recently published by the current authors as well as new experimental data from...

... calculations on both the suction and the pressure side of modern turbine airfoils. Test cases include extensive experimental investigations on a high pressure turbine vane with varying surface roughness and turbulence intensity, recently published by the current authors, as well as new experimental data from...

...., increased surface roughness and near-hole obstructions. Experiments were conducted on the suction side of a scaled-up simulated turbine vane. Results from the study indicated that as much as 50% degradation occurred with upstream obstructions, but downstream obstructions actually enhanced film cooling...

... to draw a more general conclusion about the nature of random and regular roughness, a parametric study of regular roughness arrays should be performed. 07 06 2007 15 08 2007 01 08 2008 blades friction gas turbines heat transfer hydrodynamics surface roughness Increased...

...N. Sundaram; M. D. Barringer; K. A. Thole Film cooling is influenced by surface roughness and depositions that occur from contaminants present in the hot gas path, whether that film cooling occurs on the vane itself or on the endwalls associated with the vanes. Secondary flows in the endwall region...

... , the smooth wall value of Reynolds analogy, for a turbulent boundary layer was 1.2. 08 09 2006 15 11 2006 25 03 2008 convection gas turbines blades surface roughness flow simulation thermal barrier coatings boundary layer turbulence wind tunnels Land-based and aircraft gas...

... transition. To predict the onset of transition, a new correlation is presented, accounting for the influence of freestream turbulence and surface roughness. Finally, the new model is tested against transitional rough-wall boundary layer flows on high-pressure and low-pressure turbine airfoils. The proposed...

.... The results of laboratory analysis of the salt deposits are presented, providing insight into the increased surface roughness and the deposit thickness and distribution. The test data show good agreement with published stage characteristics and give valuable information regarding stage-by-stage performance...

...Maria Vera; Xue Feng Zhang; Howard Hodson; Neil Harvey This paper presents the second part of an investigation of the combined effects of unsteadiness and surface roughness on an aft-loaded ultra-high-lift low-pressure turbine (LPT) profile at low Reynolds numbers. The investigation has been...

...Qiang Zhang; Phillip M. Ligrani The effects of surface roughness and freestream turbulence level on the aerodynamic performance of a turbine vane are experimentally investigated. Wake profiles are measured with three different freestream turbulence intensity levels (1.1%, 5.4%, and 7.7%) at two...

...Yong Il Yun; Il Young Park; Seung Jin Song Turbine blades experience significant surface degradation with service. Previous studies indicate that an order-of-magnitude or greater increase in roughness height is typical, and these elevated levels of surface roughness significantly influence turbine...

...M. Stripf; A. Schulz; S. Wittig External heat transfer measurements on a highly loaded turbine vane with varying surface roughness are presented. The investigation comprises nine different roughness configurations and a smooth reference surface. The rough surfaces consist of evenly spaced truncated...