Experimental measurements of heat transfer (St) are reported for low speed flow over scaled turbine roughness models at three different freestream pressure gradients: adverse, zero (nominally), and favorable. The roughness models were scaled from surface measurements taken on actual, in-service land-based turbine hardware and include samples of fuel deposits, TBC spallation, erosion, and pitting as well as a smooth control surface. All St measurements were made in a developing turbulent boundary layer at the same value of Reynolds number An integral boundary layer method used to estimate for the smooth wall cases allowed the calculation of the Reynolds analogy Results indicate that for a smooth wall, Reynolds analogy varies appreciably with pressure gradient. Smooth surface heat transfer is considerably less sensitive to pressure gradients than skin friction. For the rough surfaces with adverse pressure gradient, St is less sensitive to roughness than with zero or favorable pressure gradient. Roughness-induced Stanton number increases at zero pressure gradient range from 16–44% (depending on roughness type), while increases with adverse pressure gradient are 7% less on average for the same roughness type. Hot-wire measurements show a corresponding drop in roughness-induced momentum deficit and streamwise turbulent kinetic energy generation in the adverse pressure gradient boundary layer compared with the other pressure gradient conditions. The combined effects of roughness and pressure gradient are different than their individual effects added together. Specifically, for adverse pressure gradient the combined effect on heat transfer is 9% less than that estimated by adding their separate effects. For favorable pressure gradient, the additive estimate is 6% lower than the result with combined effects. Identical measurements on a “simulated” roughness surface composed of cones in an ordered array show a behavior unlike that of the scaled “real” roughness models. St calculations made using a discrete-element roughness model show promising agreement with the experimental data. Predictions and data combine to underline the importance of accounting for pressure gradient and surface roughness effects simultaneously rather than independently for accurate performance calculations in turbines.
Skip Nav Destination
Article navigation
July 2004
Technical Papers
The Effect of Real Turbine Roughness With Pressure Gradient on Heat Transfer
Jeffrey P. Bons,
Jeffrey P. Bons
Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602
Search for other works by this author on:
Stephen T. McClain
Stephen T. McClain
Department of Mechanical Engineering, The University of Alabama at Birmingham, Birmingham, AL 35294
Search for other works by this author on:
Jeffrey P. Bons
Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602
Stephen T. McClain
Department of Mechanical Engineering, The University of Alabama at Birmingham, Birmingham, AL 35294
Contributed by the International Gas Turbine Institute and presented at the International Gas Turbine and Aeroengine Congress and Exhibition, Atlanta, GA, June 16–19, 2003. Manuscript received by the IGTI Dec. 2002; final revision Mar. 2003. Paper No. 2003-GT-38738. Review Chair: H. R. Simmons.
J. Turbomach. Jul 2004, 126(3): 385-394 (10 pages)
Published Online: September 3, 2004
Article history
Received:
December 1, 2002
Revised:
March 1, 2003
Online:
September 3, 2004
Citation
Bons, J. P., and McClain, S. T. (September 3, 2004). "The Effect of Real Turbine Roughness With Pressure Gradient on Heat Transfer ." ASME. J. Turbomach. July 2004; 126(3): 385–394. https://doi.org/10.1115/1.1738120
Download citation file:
Get Email Alerts
Related Articles
Modeling of Rough-Wall Boundary Layer Transition and Heat Transfer on Turbine Airfoils
J. Turbomach (April,2008)
A Critical Assessment of Reynolds Analogy for Turbine Flows
J. Heat Transfer (May,2005)
Extended Models for Transitional Rough Wall Boundary Layers With Heat Transfer—Part I: Model Formulations
J. Turbomach (July,2009)
Surface Roughness Effects on External Heat Transfer of a HP Turbine Vane
J. Turbomach (January,2005)
Related Proceedings Papers
Related Chapters
Thermal Interface Resistance
Thermal Management of Microelectronic Equipment
Extended Surfaces
Thermal Management of Microelectronic Equipment, Second Edition
Extended Surfaces
Thermal Management of Microelectronic Equipment