0
Research Papers

Experimental Study of Surface Roughness Effects on a Turbine Airfoil in a Linear Cascade— Part II: Aerodynamic Losses

[+] Author and Article Information
M. Lorenz

Institut für Thermische Strömungsmaschinen, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germanymarco.lorenz@kit.edu

A. Schulz

Institut für Thermische Strömungsmaschinen, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germanyachmed.schulz@kit.edu

H.-J. Bauer

Institut für Thermische Strömungsmaschinen, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germanyhans-joerg.bauer@kit.edu

J. Turbomach 134(4), 041007 (Jul 20, 2011) (10 pages) doi:10.1115/1.4003656 History: Received September 07, 2010; Revised December 01, 2010; Published July 20, 2011; Online July 20, 2011

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 midspan with different deterministic surface roughnesses, Part II investigates surface roughness effects on aerodynamic losses of the same airfoil. A set of different arrays of deterministic roughness (the same as used in Part I) is investigated in these experiments. The height and eccentricity of the roughness elements are varied, showing the combined influence of roughness height and anisotropy on the losses produced in the boundary layers. It is shown that the boundary layer loss is dominated by the suction side. Therefore, the investigations focus on measurements of the suction side boundary layer thickness at midspan directly upstream of the trailing edge. The experiments are conducted at several freestream turbulence levels (Tu1=1.410.1%) and different Reynolds numbers. The measurements reveal that suction side boundary layer thickness is increased by up to 190% if surface roughness shifts the transition onset upstream. However, in some cases, at low Reynolds numbers and freestream turbulence, surface roughness suppresses boundary layer separation and decreases the trailing edge boundary layer thickness by up to 30%.

FIGURES IN THIS ARTICLE
<>
Copyright © 2012 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Schematic view of test facility

Grahic Jump Location
Figure 2

Test facility with linear cascade

Grahic Jump Location
Figure 7

Roughness effects on the turbulent boundary layer (measurement at the suction side trailing edge: s/c=1.32)

Grahic Jump Location
Figure 8

Influence of surface roughness height on the trailing edge boundary layer

Grahic Jump Location
Figure 9

Combined effect of surface roughness height and eccentricity on the trailing edge boundary layer

Grahic Jump Location
Figure 3

Schematic drawing of surface roughness

Grahic Jump Location
Figure 4

Boundary layer measurements at the trailing edge on suction and pressure sides

Grahic Jump Location
Figure 5

Mach number distribution for Tu1=1.4%

Grahic Jump Location
Figure 6

Suction side momentum thickness on a smooth airfoil

Grahic Jump Location
Figure 10

Roughness induced augmentation of suction side momentum thickness at different Re1,c and Tu1

Grahic Jump Location
Figure 11

Oil paint visualization for smooth blade at Re1,c=250,000 for low and high Tu1(32)

Grahic Jump Location
Figure 12

Roughness induced augmentation of suction side momentum thickness at Re1,c=250,000 for low and high Tu1

Grahic Jump Location
Figure 13

Influence of freestream turbulence on suction side momentum thickness

Tables

Errata

Discussions

Related

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In