The Many Faces of Turbine Surface Roughness

2001 ◽  
Vol 123 (4) ◽  
pp. 739-748 ◽  
Author(s):  
Jeffrey P. Bons ◽  
Robert P. Taylor ◽  
Stephen T. McClain ◽  
Richard B. Rivir
Keyword(s):  
Surface Roughness ◽  
Film Cooling ◽  
Smooth Surface ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Surface Conditions ◽  
The Many ◽  
Autocorrelation Length ◽  
Skewness And Kurtosis ◽  
Dimensional Surface

Results are presented for contact stylus measurements of surface roughness on in-service turbine blades and vanes. Nearly 100 turbine components were assembled from four land-based turbine manufacturers. Both coated and uncoated, cooled and uncooled components were measured, with part sizes varying from 2 to 20 cm. Spanwise and chordwise two-dimensional roughness profiles were taken on both pressure and suction surfaces. Statistical computations were performed on each trace to determine centerline averaged roughness, rms roughness, and peak to-valley height. In addition, skewness and kurtosis were calculated; as well as the autocorrelation length and dominant harmonics in each trace. Extensive three-dimensional surface maps made of deposits, pitting, erosion, and coating spallation expose unique features for each roughness type. Significant spatial variations are evidenced and transitions from rough to smooth surface conditions are shown to be remarkably abrupt in some cases. Film cooling sites are shown to be particularly prone to surface degradation.

The Many Faces of Turbine Surface Roughness

2001 ◽  
Author(s):  
Jeffrey P. Bons ◽  
Robert P. Taylor ◽  
Stephen T. McClain ◽  
Richard B. Rivir
Keyword(s):  
Surface Roughness ◽  
Film Cooling ◽  
Smooth Surface ◽  
Turbine Blades ◽  
Spatial Variations ◽  
Surface Degradation ◽  
Surface Conditions ◽  
The Many ◽  
Autocorrelation Length ◽  
Skewness And Kurtosis

Results are presented for contact stylus measurements of surface roughness on in-service turbine blades and vanes. Nearly 100 turbine components were assembled from four land-based turbine manufacturers. Both coated and uncoated, cooled and uncooled components were measured, with part sizes varying from 2 to 20cm. Spanwise and chordwise 2D roughness profiles were taken on both pressure and suction surfaces. Statistical computations were performed on each trace to determine centerline averaged roughness, rms roughness, and peak to valley height. In addition, skewness and kurtosis were calculated as well as the autocorrelation length and dominant harmonics in each trace. Extensive 3D surface maps made of deposits, pitting, erosion, and coating spallation expose unique features for each roughness type. Significant spatial variations are evidenced and transitions from rough to smooth surface conditions are shown to be remarkably abrupt in some cases. Film cooling sites are shown to be particularly prone to surface degradation.

A Parametric Analysis of the Gear Surface Roughness After Hobbing

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Lars Vedmar
Keyword(s):  
Surface Roughness ◽  
Smooth Surface ◽  
Three Dimensional ◽  
Surface Topology ◽  
Roughness Parameters ◽  
Surface Geometry ◽  
Manufacturing Method ◽  
Differentiable Functions ◽  
Involute Gears ◽  
Dimensional Surface

Hobbing is a common manufacturing method when producing helical, involute gears. In order to give the manufactured gear a controlled surface smoothness, a method to, very accurately, determine the achieved surface geometry is needed. In this report, the cutting surfaces of the tool, of which the cutting edges are the boundaries, are assumed to be plane in arbitrary directions. They are mathematically described using parametric and analytically differentiable functions. These functions give the possibility to determine the geometry of the three-dimensional surface of the manufactured gear, without any additional numeric approximations. By comparing this surface with the smooth surface of an ideal gear, the roughness of the surface can be determined. An example is given in which the surface topology and the characteristic surface roughness parameters are determined.

Enhancement of Heat Transfer Performance in Nuclear Fuel Rod Using Nanofluids and Surface Roughness Technique

2015 ◽  
Author(s):  
Kang Liu ◽  
Titan C. Paul ◽  
Leo A. Carrilho ◽  
Jamil A. Khan
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Nuclear Fuel ◽  
Three Dimensional ◽  
Pressurized Water ◽  
Bulk Fluid ◽  
Fuel Rod ◽  
Dimensional Surface

The experimental investigations were carried out of a pressurized water nuclear reactor (PWR) with enhanced surface using different concentration (0.5 and 2.0 vol%) of ZnO/DI-water based nanofluids as a coolant. The experimental setup consisted of a flow loop with a nuclear fuel rod section that was heated by electrical current. The fuel rod surfaces were termed as two-dimensional surface roughness (square transverse ribbed surface) and three-dimensional surface roughness (diamond shaped blocks). The variation in temperature of nuclear fuel rod was measured along the length of a specified section. Heat transfer coefficient was calculated by measuring heat flux and temperature differences between surface and bulk fluid. The experimental results of nanofluids were compared with the coolant as a DI-water data. The maximum heat transfer coefficient enhancement was achieved 33% at Re = 1.15 × 105 for fuel rod with three-dimensional surface roughness using 2.0 vol% nanofluids compared to DI-water.

scholarly journals Comparison of Two-Equation Turbulence Models for Prediction of Heat Transfer on Film-Cooled Turbine Blades

1997 ◽  
Author(s):  
Vijay K. Garg ◽  
Ali A. Ameri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Computer Time ◽  
Suction Surface ◽  
The Heat Transfer Coefficient

A three-dimensional Navier-Stokes code has been used to compute the heat transfer coefficient on two film-cooled turbine blades, namely the VKI rotor with six rows of cooling holes including three rows on the shower head, and the C3X vane with nine rows of holes including five rows on the shower head. Predictions of heat transfer coefficient at the blade surface using three two-equation turbulence models, specifically, Coakley’s q-ω model, Chien’s k-ε model and Wilcox’s k-ω model with Menter’s modifications, have been compared with the experimental data of Camci and Arts (1990) for the VKI rotor, and of Hylton et al. (1988) for the C3X vane along with predictions using the Baldwin-Lomax (B-L) model taken from Garg and Gaugler (1995). It is found that for the cases considered here the two-equation models predict the blade heat transfer somewhat better than the B-L model except immediately downstream of the film-cooling holes on the suction surface of the VKI rotor, and over most of the suction surface of the C3X vane. However, all two-equation models require 40% more computer core than the B-L model for solution, and while the q-ω and k-ε models need 40% more computer time than the B-L model, the k-ω model requires at least 65% more time due to slower rate of convergence. It is found that the heat transfer coefficient exhibits a strong spanwise as well as streamwise variation for both blades and all turbulence models.

scholarly journals Numerical Prediction of Film Cooling Effectiveness and the Associated Aerodynamic Losses With a Three-Dimensional Calculation Procedure

1990 ◽  
Author(s):  
G. H. Dibelius ◽  
R. Pitt ◽  
B. Wen
Keyword(s):  
Experimental Data ◽  
Film Cooling ◽  
Reverse Flow ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Temperature Pattern ◽  
Main Stream ◽  
Cooling Efficiency ◽  
Film Cooling Effectiveness ◽  
Aerodynamic Losses

Film cooling of turbine blades by injecting air through holes or slots affects the main stream flow. A numerical model has been developed to predict the resulting three-dimensional flow and the temperature pattern under steady flow conditions. An elliptic procedure is used in the near injection area to include reverse flow situations, while in the upstream area as well as far downstream a partial-parabolic procedure is applied. As first step an adiabatic wall has been assumed as boundary condition, since for this case experimental data are readily available for comparison. At elevated momentum blowing rates, zones of reverse flow occur downstream of the injection holes resulting in a decrease of cooling efficiency. A variation of the relevant parameters momentum blowing rate m, injection angle α and ratio of hole spacing to diameter s/d revealed the combination of m ≈ 1, α ≈ 30° and s/d ≈ 2 to be the optimum with respect to the averaged cooling efficiency and to the aerodynamic losses. Cooling is more efficient with slots than with a row of holes not considering the related problems of manufacture and service life. The calculated temperature patterns compare well with the experimental data available.

scholarly journals Multiscale three-dimensional surface reconstruction and surface roughness of porcine left anterior descending coronary arteries

2019 ◽  
Vol 6 (9) ◽  
pp. 190915 ◽  
Author(s):  
Hanna E. Burton ◽  
Rachael Cullinan ◽  
Kyle Jiang ◽  
Daniel M. Espino
Keyword(s):  
Surface Roughness ◽  
Coronary Arteries ◽  
Medical Devices ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Force Microscopy ◽  
Optical Scanning ◽  
Atomic Force ◽  
Reconstructed Surface ◽  
Dimensional Surface

The aim of this study was to investigate the multiscale surface roughness characteristics of coronary arteries, to aid in the development of novel biomaterials and bioinspired medical devices. Porcine left anterior descending coronary arteries were dissected ex vivo , and specimens were chemically fixed and dehydrated for testing. Surface roughness was calculated from three-dimensional reconstructed surface images obtained by optical, scanning electron and atomic force microscopy, ranging in magnification from 10× to 5500×. Circumferential surface roughness decreased with magnification, and microscopy type was found to influence surface roughness values. Longitudinal surface roughness was not affected by magnification or microscopy types within the parameters of this study. This study found that coronary arteries exhibit multiscale characteristics. It also highlights the importance of ensuring consistent microscopy parameters to provide comparable surface roughness values.

Measuring and Quantifying the Surface-Roughness Anisotropy of Modeled and Industrially Produced Surfaces

2005 ◽  
Vol 6-8 ◽  
pp. 573-582 ◽  
Author(s):  
C.M. Wichern ◽  
W. Rasp
Keyword(s):  
Surface Roughness ◽  
Rolling Direction ◽  
Three Dimensional ◽  
Roughness Parameter ◽  
Orientation Angle ◽  
Textured Surface ◽  
Angular Orientation ◽  
Textured Surfaces ◽  
Average Roughness ◽  
Dimensional Surface

‘Three-dimensional surface profilometry’ when used for analysis and product specification reports roughness parameters that provide an average surface description over a relatively large area. Many commercial sheet steels are produced with special textured surfaces for tribological benefits or appearance benefits. These surfaces, as well as others, may demonstrate high levels of roughness anisotropy that is not quantifiable by simple three dimensional surface parameters. This anisotropy can play an important role in the surface appearance of the finished product and in the tribological behaviour during forming. The current work presents a method for quantifying surface-roughness features as a function of angular orientation with respect to rolling direction. The measurement methodology was applied to several model surfaces and one industrially produced electron-beam textured-surface (EBT). This methodology extracts multiple surface-height profiles of the same angular orientation from a single surface and calculates an average roughness parameter for the orientation angle based on the multiple profiles. Particularly interesting results were the large number of profiles necessary to obtain repeatable values for the roughness variation with respect to direction and the strong influence of surface feature size on the repeatability of said results. These results indicate that care must be taken when using a single extracted profile to represent a ‘three-dimensional’ surface.

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