Ash Deposition, Gas Turbine, Deposition


A thermal barrier coating (TBC)-coated turbine blade coupon was exposed to successive deposition in an accelerated deposition facility simulating flow conditions at the inlet to a first stage high pressure turbine (T=1150 C, M=0.31). The combustor exit flow was seeded with dust particulate that would typically be ingested by a large utility power plant. The turbine coupon was subjected to four successive 2 h deposition tests. The particulate loading was scaled to simulate 0.02 parts per million weight (ppmw) of particulate over 3 months of continuous gas turbine operation for each 2 h laboratory simulation (for a cumulative 1 year 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, scaled models were produced for testing in a low-speed wind tunnel with a turbulent, zero pressure gradient boundary layer at Re=750,000. The average surface heat transfer coefficient was measured using a transient surface temperature measurement technique. Stanton number increases initially with deposition but then levels off as the surface becomes less peaked. Subsequent deposition exposure then produces a second increase in St. Surface maps of St highlight the local influence of deposit peaks with regard to heat transfer.

Original Publication Citation

Bons, J. P., J. E. Wammack, J. Crosby, D. Fletcher, T. H. Fletcher, “Evolution of Surface Deposits on a High Pressure Turbine Blade, Part II: Convective Heat Transfer,” ASME Journal of Turbomachinery, 130, 021021-1 thru 7 (2008).

Document Type

Peer-Reviewed Article

Publication Date







Ira A. Fulton College of Engineering


Chemical Engineering

University Standing at Time of Publication

Full Professor