0
Research Papers

Evolution of Surface Deposits on a High-Pressure Turbine Blade—Part I: Physical Characteristics

[+] Author and Article Information
James E. Wammack, Jared Crosby, Daniel Fletcher, Jeffrey P. Bons

Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602

Thomas H. Fletcher

Department of Chemical Engineering, Brigham Young University, Provo, UT 84602

J. Turbomach 130(2), 021020 (Mar 25, 2008) (8 pages) doi:10.1115/1.2752182 History: Received September 08, 2006; Revised November 14, 2006; Published March 25, 2008

Turbine blade coupons with three different surface treatments were exposed to deposition conditions in an accelerated deposition facility. The facility simulates the flow conditions at the inlet to a first stage high-pressure turbine (T=1150°C, M=0.31). The combustor exit flow is seeded with dust particulate that would typically be ingested by a large utility power plant. The three coupon surface treatments included: (1) bare polished metal; (2) polished thermal barrier coating with bondcoat; and (3) unpolished oxidation resistant bondcoat. Each coupon was subjected to four successive 2h deposition tests. The particulate loading was scaled to simulate 0.02 parts per million weight (ppmw) of particulate over 3months of continuous gas turbine operation for each 2h laboratory simulation (for a cumulative 1year of operation). Three-dimensional maps of the deposit-roughened surfaces were created between each test, representing a total of four measurements evenly spaced through the lifecycle of a turbine blade surface. From these measurements the surface topology and roughness statistics were determined. Despite the different surface treatments, all three surfaces exhibited similar nonmonotonic changes in roughness with repeated exposure. In each case, an initial buildup of isolated roughness peaks was followed by a period when valleys between peaks were filled with subsequent deposition. This trend is well documented using the average forward facing roughness angle in combination with the average roughness height as characteristic roughness metrics. Deposition-related mechanisms leading to spallation of the thermal barrier coated coupons are identified and documented.

FIGURES IN THIS ARTICLE
<>
Copyright © 2008 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Distribution of Ra(μm) for multiple aero and land-based turbine blades (from Refs. 5-6)

Grahic Jump Location
Figure 2

Turbine Accelerated Deposition Facility

Grahic Jump Location
Figure 3

Schematic of TADF turbine coupon holder

Grahic Jump Location
Figure 4

Streamwise-averaged surface traces of the bare metal coupon deposit at five different points in its evolution

Grahic Jump Location
Figure 5

Surface topologies of 3mm×5mm section of deposit on bare metal coupon after each burn. Vertical scale shows peak roughness height: (a) before Burn 1, (b) after Burn 1; (c) after Burn 2; (d) after Burn 3; and (e) after Burn 4.

Grahic Jump Location
Figure 6

Roughness statistics for the bare metal coupon deposit

Grahic Jump Location
Figure 7

Streamwise-averaged surface traces of the TBC1 coupon deposit at five different points in its evolution

Grahic Jump Location
Figure 8

Surface topologies of 5.7mm×9.5mm section of deposit on the TBC1 coupon after each burn. Vertical scale shows peak roughness height: (a) before Burn 1; (b) after Burn 1; (c) after Burn 2; (d) after Burn 3; and (e) after Burn 4.

Grahic Jump Location
Figure 9

Roughness statistics for the TBC1 and TBC2 coupon deposits

Grahic Jump Location
Figure 10

Surface topologies of 8mm×18mm section of deposit on unpolished coupon after each burn. Vertical scale shows peak roughness height: (a) before Burn 1; (b) after Burn 1; (c) after Burn 2; (d) after Burn 3; and (e) After Burn 4.

Grahic Jump Location
Figure 11

Roughness statistics for the unpolished coupon deposit

Grahic Jump Location
Figure 12

ESEM cross section of spalled region of the TBC1 coupon and spalled chip: (a) edge of spalled TBC chip removed after Burn 3 (image enlarged for clarity—see scale); and (b) spalled region of TBC1 coupon after Burn 4

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