Development of Taylor-Go¨rtler Vortices Over the Pressure Surface of a Turbine Blade

2005 ◽  
Vol 127 (5) ◽  
pp. 540-543 ◽  
Author(s):  
H. P. Wang ◽  
S. J. Olson ◽  
R. J. Goldstein
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Turbine Blade ◽  
Flow Direction ◽  
Mass Transfer Rate ◽  
Leading Edge ◽  
Flow Region ◽  
Freestream Turbulence ◽  
Pressure Surface ◽  
Naphthalene Sublimation Technique

The naphthalene sublimation technique is used to investigate the development of Taylor-Go¨rtler vortices over the pressure surface of a simulated high performance turbine blade. Large spanwise variation in mass transfer is observed downstream on the pressure surface in the two-dimensional flow region for cases with low freestream turbulence, indicating the existence of Taylor-Go¨rtler vortices. Different average and local mass transfer rates for the same flow conditions suggest that roughness variation near the leading edge affects the initial formation of Taylor-Go¨rtler vortices. Larger and more uniformly distributed roughness at the leading edge produces much stronger Taylor-Go¨rtler vortices downstream and greatly enhances the mass transfer rate. The variation between the vortices does not change appreciably along the flow direction. The flow in the boundary layer is laminar over the entire pressure surface. In the presence of external disturbances such as high freestream turbulence or a boundary layer trip, no Taylor-Go¨rtler vortices are observed.

Effect of Wake-Disturbed Flow on Heat (Mass) Transfer to a Turbine Blade

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
S. Olson ◽  
S. Sanitjai ◽  
K. Ghosh ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Heat Mass Transfer ◽  
Turbine Blades ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Disturbed Flow ◽  
Linear Cascade ◽  
Naphthalene Sublimation Technique

This study investigates the effect of wakes in the presence of varying levels of background freestream turbulence on the heat (mass) transfer from gas turbine blades. Measurements using the naphthalene sublimation technique provide local values of the mass transfer coefficient on the pressure and suction surfaces of a simulated turbine blade in a linear cascade. Experimental parameters studied include the pitch of the wake-generating blades (vanes), blade-row separation, Reynolds number, and the freestream turbulence level. The disturbed flow strongly affects the mass transfer Stanton number on both sides of the blade, particularly along the suction surface. An earlier transition to a turbulent boundary layer occurs with increased background turbulence, higher Reynolds number, and from wakes shed from vanes placed upstream of the linear cascade. Note that once the effects on mass transfer are known, similar variation on heat transfer can be inferred from the heat/mass transfer analogy.

Darryl E. Metzger Memorial Session Paper: The Influence of Secondary Flows Near the Endwall and Boundary Layer Disturbance on Convective Transport From a Turbine Blade

1995 ◽  
Vol 117 (4) ◽  
pp. 657-665 ◽  
Author(s):  
R. J. Goldstein ◽  
H. P. Wang ◽  
M. Y. Jabbari
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Leading Edge ◽  
Flow Region ◽  
Suction Side ◽  
Convective Transport ◽  
Pressure Side ◽  
Suction Surface ◽  
Passage Vortex

A naphthalene sublimation technique is used to investigate convective transport from a simulated turbine blade in a stationary linear cascade. In some of the tests undertaken, a trip wire is stretched along the span of the blade near the leading edge. The disturbance produced by tripping the boundary layers on the blade near the leading edge causes early boundary layer transition, creates high mass transfer rate on the pressure side and in the laminar flow region on the suction side, but lowers the transfer rate in the turbulent flow region on the suction side. Comparison is made with other heat and mass transfer studies in the two-dimensional region far from the endwall and good agreement is found. Near the endwall, flow visualization indicates a strong secondary flow pattern. The impact of vortices initiated near the endwall on the laminar–turbulent transition extends three-dimensional effects to about 0.8 chord lengths on the suction side and to about 0.2 chord lengths on the pressure side away from the endwall. The effect of the passage vortex and the new vortex induced by the passage vortex on mass transfer is clearly seen and can be traced along the suction surface of the blade. Close to the endwall the highest mass transfer rate on the suction surface is not found near the leading edge. It occurs at about 27 percent of the curvilinear distance from the stagnation line to the trailing edge where a strong main flow and the secondary passage flow from the pressure side of the adjacent blade interact. The influences of some small but very intense corner vortices and the passage vortex on mass transfer are also observed on both surfaces of the blade.

scholarly journals Surface Injection Effect on Mass Transfer From a Cylinder in Crossflow: A Simulation of Film Cooling in the Leading Edge Region of a Turbine Blade

1990 ◽  
Vol 112 (3) ◽  
pp. 418-427 ◽  
Author(s):  
J. Karni ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Edge Region ◽  
Stagnation Region ◽  
Stagnation Line ◽  
Naphthalene Sublimation Technique ◽  
Circular Holes ◽  
Cooling Effects

A naphthalene sublimation technique is used to study the effect of surface injection on the mass (heat) transfer from a circular cylinder in crossflow. Using a heat/mass transfer analogy the results can be used to predict film cooling effects in the leading edge region of a turbine blade. Air injection through one row of circular holes is employed in the stagnation region of the cylinder. Streamwise and spanwise injection inclinations are studied separately, and the effects of blowing rate and injection location relative to the cylinder front stagnation line are investigated. Streamwise injection produces significant mass transfer increases downstream of the injection holes, but a relatively small increase is observed between holes, normal to the injection direction. The mass transfer distribution, measured with spanwise injection through holes located near the cylinder front stagnation line, is extremely sensitive to small changes in the injection hole location relative to stagnation. When the centers of the spanwise injection holes are located 5 deg or more from the stagnation line, the holes lie entirely on one side of the stagnation line and the injection affects the mass transfer only on that side of the cylinder, approaching the pattern observed with streamwise injection.

scholarly journals The Influence of Secondary Flows Near the Endwall and Boundary Layer Disturbance on Convective Transport From a Turbine Blade

1994 ◽  
Author(s):  
R. J. Goldstein ◽  
H. P. Wang ◽  
M. Y. Jabbari
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Leading Edge ◽  
Flow Region ◽  
Suction Side ◽  
Convective Transport ◽  
Pressure Side ◽  
Suction Surface ◽  
Passage Vortex

A naphthalene sublimation technique is used to investigate convective transport from a simulated turbine blade in a stationary linear cascade. In some of the tests undertaken a trip wire is stretched along the span of the blade near the leading edge. The disturbance produced by tripping the boundary layers on the blade near the leading edge causes early boundary layer transition, creates high mass transfer rate on the pressure side and in the laminar flow region on the suction side, but lowers the transfer rate in the turbulent flow region on the suction side. Comparison is made with other heat and mass transfer studies in the two dimensional region far from the endwall and good agreement is found. Near the endwall, flow visualization indicates a strong secondary flow pattern. The impact of vortices initiated near the endwall on the laminar-turbulent transition extends three dimensional effects to about 0.8 chord lengths on the suction side and to about 0.2 chord lengths on the pressure side away from the endwall. The effect of the passage vortex and the new vortex induced by the passage vortex on mass transfer is clearly seen and can be traced along the suction surface of the blade. Close to the endwall the highest mass transfer rate on the suction surface is not found near the leading edge. It occurs at about 27% of the curvilinear distance from the stagnation line to the trailing edge where a strong main flow and the secondary passage flow from the pressure side of the adjacent blade interact. The influences of some small but very intense corner vortices and the passage vortex on mass transfer are also observed on both surfaces of the blade.

scholarly journals Surface Injection Effect on Mass Transfer From a Cylinder in Crossflow: A Simulation of Film Cooling in the Leading Edge Region of a Turbine Blade

1989 ◽  
Author(s):  
J. Karni ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Edge Region ◽  
Stagnation Region ◽  
Stagnation Line ◽  
Naphthalene Sublimation Technique ◽  
Circular Holes ◽  
Cooling Effects

A naphthalene sublimation technique is used to study the effect of surface injection on the mass (heat) transfer from a circular cylinder in crossflow. Using a heat/mass transfer analogy the results can be used to predict film cooling effects in the leading edge region of a turbine blade. Air injection through one row of circular holes is employed in the stagnation region of the cylinder. Streamwise and spanwise injection inclinations are studied separately, and the effects of blowing rate and injection location relative to the cylinder front stagnation line are investigated. Streamwise injection produces significant mass transfer increases downstream of the injection holes, but a relatively small increase is observed between holes, normal to the injection direction. The mass transfer distribution, measured with spanwise injection through holes located near the cylinder front stagnation line, is extremely sensitive to small changes in the injection hole location relative to stagnation. When the centers of the spanwise injection holes are located 5° or more from the stagnation line, the holes lay entirely on one side of the stagnation line and the injection affects the mass transfer only on that side of the cylinder, approaching the pattern observed with streamwise injection.

Mass transfer from a laminar stream to a flat plate

1954 ◽  
Vol 221 (1144) ◽  
pp. 100-104 ◽  
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Flat Plate ◽  
Transfer Rate ◽  
Kinematic Viscosity ◽  
Mass Transfer Rate ◽  
Leading Edge ◽  
Square Root ◽  
Transfer Number ◽  
Very High

The Kármán-Pohlhausen-Kroujiline method is used to calculate the mass-transfer rate from a laminar stream to a flat plate, for fluids of which the diffusion coefficient is not greatly different from the kinematic viscosity. Particular attention is paid to the very high rates of mass transfer occurring when the transfer number B approaches -1; under these circumstances it is shown that the transfer rate is proportional to (1+ B ) -½ . In aerodynamic terms the problem may be regarded as that of a laminar boundary layer with suction distributed in proportion to the reciprocal of the square root of the distance from the leading edge.

Effect of Upstream Shear on Flow and Heat (Mass) Transfer Over a Flat Plate

2008 ◽  
Author(s):  
Kalyanjit Ghosh ◽  
R. J. Goldstein
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Flow Direction ◽  
Velocity Ratio ◽  
Leading Edge ◽  
Surface Velocity ◽  
Freestream Velocity ◽  
Inner Region

A parametric study is conducted to investigate the effect of wall shear on a two-dimensional turbulent boundary layer. The shear is imparted by a moving belt, flush with the wall, translating in the flow direction. Velocity and mass transfer experiments have been performed for four surface-to-freestream velocity ratios (0, 0.38, 0.52, 0.65) with a Reynolds number based on the momentum thickness between 770 and 1776. The velocity data indicate that the location of the ‘virtual origin’ of the turbulent boundary layer ‘moves’ downstream towards the trailing edge of the belt with increasing surface velocity. The highest velocity ratio represents a case which is responsible for the removal of the inner region of the boundary layer. Mass transfer measurements downstream of the belt show the presence of a local minimum in the variation of the Stanton vs. Reynolds number for the highest velocity ratio. Downstream of this minimum, approximately 1 cm from the leading edge of the mass transfer plate, the characteristics of the turbulent boundary layer are restored and the data fall back on the empirical variation of the Stanton number with Reynolds number.

scholarly journals Effect of Upstream Wake on Shower-Head Film Cooling

1996 ◽  
Vol 2 (4) ◽  
pp. 269-280
Author(s):  
Ping-Hei Chen ◽  
Jr-Ming Miao
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Mass Transfer Rate ◽  
Leading Edge ◽  
Suction Side ◽  
Convective Transport ◽  
Wake Flow ◽  
Naphthalene Sublimation Technique ◽  
Naphthalene Sublimation ◽  
The Difference

The present study aims to investigate the effect of an upstream wake on the convective transport phenomena over a turbine blade with shower-head film cooling. A naphthalene sublimation technique was implemented to obtain the detailed mass transfer distributions on both suction and pressure surfaces of the test blade. All mass transfer runs were conducted on a blowing-type wind tunnel with a six-blade linear cascade. The leading edge of the test blade was drilled with three rows of equally spaced injection holes. The upstream wake was simulated by a circular bar with the same diameter as that of the trailing edge of the test blade.The test condition was fixed at Re = 397,000, M = 0.8, and Tu = 0.4% and upstream wakes were generated at four different locations ahead of the blade cascade. Measured results show that there is a difference in mass transfer rate from the case without upstream wake. This difference is greater on the suction side than on the pressure side. The difference results from the interaction between the wake flow that is induced by the upstream wake and the injection flows that are ejected from the multi-rows of injection holes on the test blade. It was also found that the location of upstream wake generation significantly affects the mass transfer distributions on both surfaces of test blade.

scholarly journals Mass Transfer over a Film-Cooled Turbine Blade

1996 ◽  
Vol 2 (4) ◽  
pp. 221-236
Author(s):  
Ping-Hei Chen ◽  
Jr-Ming Miao
Keyword(s):  
Mass Transfer ◽  
Turbine Blade ◽  
Leading Edge ◽  
Secondary Flows ◽  
Spanwise Direction ◽  
Edge Region ◽  
Blade Surface ◽  
Naphthalene Sublimation Technique ◽  
Naphthalene Sublimation ◽  
Sublimation Technique

A naphthalene sublimation technique was employed to study the mass transfer distributions over a turbine blade surface with secondary flows ejected in the spanwise direction through three rows of equally-spaced injection holes located in the leading edge region. The mass transfer measurements were conducted in a range of blowing ratios from 0.6 to 1.2 at two different mainstream turbulence levels (0.4% and 6.0%) while keeping the exit Reynolds number,Re⁡2, at a constant value of 397,000.

scholarly journals Effect of High Freestream Turbulence With Large Length Scale on Blade Heat/Mass Transfer

1998 ◽  
Author(s):  
H. P. Wang ◽  
R. J. Goldstein ◽  
S. J. Olson
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Heat Mass Transfer ◽  
Mass Transfer Rate ◽  
Reynolds Numbers ◽  
Boundary Layer Transition ◽  
Length Scale ◽  
Freestream Turbulence ◽  
Large Length ◽  
Large Length Scale

The naphthalene sublimation technique is used to investigate the influence of high freestream turbulence with large length scale on the heat/mass transfer from a turbine blade in a highly accelerated linear cascade. The experiments are conducted at four exit Reynolds numbers, ranging from 2.4 × 105 to 7.8 × 105, with freestream turbulence of 3%, 8.5% and 18% and corresponding integral length scales of 0.9 cm, 2.6 cm and 8 cm, respectively. On the suction surface, the heat/mass transfer rate is significantly enhanced by high freestream turbulence due to an early boundary layer transition. By contrast, the transition occurs very late, and may not occur at very low Reynolds numbers with low freestream turbulence. In the turbulent boundary layer, lower heat/mass transfer rates are found for the highest freestream turbulence level with large length scale than for the moderate turbulence levels with relatively small scales. Similar phenomena also occur at the leading edge. However, the effect of turbulence is not as pronounced in the laminar boundary layer.

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