The Influence of Large-Scale High-Intensity Turbulence on Vane Heat Transfer

1997 ◽  
Vol 119 (1) ◽  
pp. 23-30 ◽  
Author(s):  
F. E. Ames
Keyword(s):  
Heat Transfer ◽  
High Intensity ◽  
Large Scale ◽  
Reynolds Numbers ◽  
Surface Heat ◽  
Grid Turbulence ◽  
Stagnation Region ◽  
Linear Cascade ◽  
Pressure Surface ◽  
Scale Turbulence

An experimental research program was undertaken to examine the influence of large-scale high-intensity turbulence on vane heat transfer. The experiment was conducted in a four-vane linear cascade at exit Reynolds numbers of 500,000 and 800,000 based on chord length. Heat transfer measurements were made for four inlet turbulence conditions including a low turbulence case (Tu ≅ 1 percent), a grid turbulence case (Tu ≅ 7.5 percent), and two levels of large-scale turbulence generated with a mock combustor at two upstream locations (Tu ≅ 12 percent and 8 percent). The heat transfer data demonstrated that the length scale, Lu, has a significant effect on stagnation region and pressure surface heat transfer.

scholarly journals The Influence of Large Scale High Intensity Turbulence on Vane Heat Transfer

1995 ◽  
Author(s):  
Forrest E. Ames
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
High Intensity ◽  
Large Scale ◽  
Grid Turbulence ◽  
Absolute Level ◽  
Relative Level ◽  
Stagnation Region ◽  
Pressure Surface ◽  
Heat Transfer Augmentation

An experimental research program was undertaken to examine the influence of large scale high intensity turbulence on vane heat transfer. The experiment was conducted in a four vane linear cascade at exit Reynolds numbers of 500,000 and 800,000 based on chord length corresponding to exit Mach numbers of 0.17 and 0.27. Heat transfer measurements were made for four inlet turbulence conditions including a low turbulence case (Tu ≅ 1%), a grid turbulence case (Tu ≅ 7.5%), and two levels of large scale turbulence generated with a mock combustor at two upstream locations (Tu ≅ 12% & Tu ≅ 8%). The heat transfer data demonstrated that the length scale, Lu, has a significant effect on stagnation region and pressure surface heat transfer. The average heat transfer augmentation over the pressure surface was found to scale reasonably well on the relative level of dissipation. The stagnation region heat transfer correlated well on the {Tu ReD5/12 (Lu/D)−1/3} parameter of Ames and Moffat (1990). The dependence of heat transfer augmentation on Reynolds number was estimated to scale on the 1/3 power for the pressure surface. The absolute level of heat transfer augmentation was found to be highest near the stagnation region. The combustor closely coupled to the cascade produced an average augmentation on the pressure surface of 56 percent at a Reynolds number of 800,000.

Effects of Aeroderivative Combustor Turbulence on Endwall Heat Transfer Distributions Acquired in a Linear Vane Cascade

2002 ◽  
Author(s):  
Forrest E. Ames ◽  
Pierre A. Barbot ◽  
Chao Wang
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Combustion System ◽  
Three Dimensional Flow ◽  
Linear Cascade ◽  
High Turbulence ◽  
Turbulence Condition ◽  
Vortex Systems

Vane endwall heat transfer distributions are documented for a mock aeroderivative combustion system and for a low turbulence condition in a large-scale low speed linear cascade facility. Inlet turbulence levels range from below 0.7 percent for the low turbulence condition to 14 percent for the mock combustor system. Stanton number contours are presented at both turbulence conditions for Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2,000,000. Low turbulence endwall heat transfer shows the influence of the complex three-dimensional flow field, while the effects of individual vortex systems are less evident for the high turbulence cases. Turbulent scale has been documented for the high turbulence case. Inlet boundary layers are relatively thin for the low turbulence case while inlet flow approximates a nonequilibrium or high turbulence channel flow for the mock combustor case. Inlet boundary layer parameters are presented across the inlet passage for the three Reynolds numbers and both the low turbulence and mock combustor inlet cases. Both midspan and 95 percent span pressure contours are included. This research provides a well-documented database taken across a range of Reynolds numbers and turbulence conditions for assessment of endwall heat transfer predictive capabilities.

Measurement and Prediction of Heat Transfer Distributions on an Aft Loaded Vane Subjected to the Influence of Catalytic and Dry Low NOx Combustor Turbulence

2003 ◽  
Author(s):  
F. E. Ames ◽  
M. Argenziano ◽  
C. Wang
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Energy Scale ◽  
Test Case ◽  
Suction Surface ◽  
Stagnation Region ◽  
Data Set ◽  
Transfer Rates ◽  
Pressure Surface ◽  
Heat Transfer Augmentation

This paper documents heat transfer rates on an aft loaded vane subject to turbulence generated by mock combustion configurations representative of recently developed catalytic and dry low NOx (DLN) combustors. New combustion systems developed for low emissions have produced substantial changes to the characteristics of inlet turbulence entering nozzle guide vanes. Aft loaded vane designs can have an impact on surface heat transfer distributions by accelerating boundary layers for a greater portion of the suction surface. Four different inlet turbulence conditions with intensities ranging up to 21 percent are documented in this study and vane heat transfer rates are acquired at vane exit chord Reynolds numbers ranging from 500,000 to 2,000,000. Heat transfer distributions show the influence of the turbulence conditions on heat transfer augmentation and transition. Cascade aerodynamics are well documented and match pressure distributions predicted by a commercial CFD code for this large scale low speed facility. The aft loaded vane pressure distribution exhibits a minimum value at about 50 percent arc on the suction surface. Laminar heat transfer augmentation in the stagnation region and on the pressure surface have scaled well on theoretical parameters based on turbulence intensity, Reynolds number, and energy scale. Predictive comparisons are shown based on a two-dimensional boundary layer code using an algebraic turbulence model for augmentation as well as a transition model. This comprehensive vane heat transfer data set is expected to represent an excellent test case for vane heat transfer predictive methods.

Effect of Unsteady Wake With Trailing Edge Coolant Ejection on Detailed Heat Transfer Coefficient Distributions for a Gas Turbine Blade

1997 ◽  
Vol 119 (2) ◽  
pp. 242-248 ◽  
Author(s):  
H. Du ◽  
S. Ekkad ◽  
J.-C. Han
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Free Stream ◽  
Surface Heat ◽  
Trailing Edge ◽  
Surface Heat Transfer ◽  
Linear Cascade ◽  
Pressure Surface ◽  
Unsteady Wake

Detailed heat transfer coefficient distributions on a turbine blade under the combined effects of trailing edge jets and unsteady wakes at various free-stream conditions are presented using a transient liquid crystal image method. The exit Reynolds number based on the blade axial chord is varied from 5.3 × 105 to 7.6 × 105 for a five blade linear cascade in a low speed wind tunnel. Unsteady wakes are produced using a spoked wheel-type wake generator upstream of the linear cascade. Upstream trailing edge jets are simulated by air ejection from holes located on the hollow spokes of the wake generator. The mass flux ratio of the jets to free-stream is varied from 0.0 to 1.0. Results show that the surface heat transfer coefficient increases with an increase in Reynolds number and also increases with the addition of unsteady wakes. Adding grid generated turbulence to the unsteady wake further enhances the blade surface heat transfer coefficients. The trailing edge jets compensate the defect in the velocity profile caused by the unsteady passing wakes and give an increase in free-stream velocity and produce a more uniformly disturbed turbulence intensity profile. The net effect is to increase both the front parts of blade suction and pressure surface heat transfer. However, the jet effect diminishes in and after the transition regions on suction surface, or far away from the leading edge on pressure surface.

Effects of Aeroderivative Combustor Turbulence on Endwall Heat Transfer Distributions Acquired in a Linear Vane Cascade

2003 ◽  
Vol 125 (2) ◽  
pp. 210-220 ◽  
Author(s):  
Forrest E. Ames ◽  
Pierre A. Barbot ◽  
Chao Wang
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Combustion System ◽  
Three Dimensional Flow ◽  
Linear Cascade ◽  
High Turbulence ◽  
Turbulence Condition ◽  
Vortex Systems

Vane endwall heat transfer distributions are documented for a mock aeroderivative combustion system and for a low turbulence condition in a large-scale low speed linear cascade facility. Inlet turbulence levels range from below 0.7% for the low turbulence condition to 14% for the mock combustor system. Stanton number contours are presented at both turbulence conditions for Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2,000,000. Low turbulence endwall heat transfer shows the influence of the complex three-dimensional flow field, while the effects of individual vortex systems are less evident for the high turbulence cases. Turbulent scale has been documented for the high turbulence case. Inlet boundary layers are relatively thin for the low turbulence case, while inlet flow approximates a nonequilibrium or high turbulence channel flow for the mock combustor case. Inlet boundary layer parameters are presented across the inlet passage for the three Reynolds numbers and both the low turbulence and mock combustor inlet cases. Both midspan and 95% span pressure contours are included. This research provides a well-documented database taken across a range of Reynolds numbers and turbulence conditions for assessment of endwall heat transfer predictive capabilities.

Effects of Catalytic and Dry Low NOx Combustor Turbulence on Endwall Heat Transfer Distributions

2005 ◽  
Vol 127 (4) ◽  
pp. 414-424 ◽  
Author(s):  
F. E. Ames ◽  
P. A. Barbot ◽  
C. Wang
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Flow Field ◽  
Large Scale ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Three Dimensional Flow ◽  
Linear Cascade ◽  
Catalytic Combustor ◽  
Vortex Systems

Endwall heat transfer distributions taken in a large-scale low speed linear cascade facility are documented for mock catalytic and dry low NOx (DLN) combustion systems. Inlet turbulence levels range from about 1.0% for the mock catalytic combustor condition to 14% for the mock dry low NOx combustor system. Stanton number contours are presented at both turbulence conditions for Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2,000,000. Catalytic combustor endwall heat transfer shows the influence of the complex three-dimensional flow field, while the effects of individual vortex systems are less evident for the mock dry low NOx cases. Turbulence scales have been documented for both cases. Inlet boundary layers are relatively thin for both the mock catalytic and DLN combustor cases. Inlet boundary layer parameters are presented across the inlet passage for the three Reynolds numbers and both the mock catalytic and DLN combustor inlet cases. Both midspan and 95% span pressure contours are included. This research provides a well-documented database taken across a range of Reynolds numbers and turbulence conditions for assessment of endwall heat transfer predictive capabilities.

Effects of Catalytic and Dry Low NOx Combustor Turbulence on Endwall Heat Transfer Distributions

2003 ◽  
Author(s):  
F. E. Ames ◽  
P. A. Barbot ◽  
C. Wang
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Flow Field ◽  
Large Scale ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Three Dimensional Flow ◽  
Linear Cascade ◽  
Catalytic Combustor ◽  
Vortex Systems

Endwall heat transfer distributions taken in a large-scale low speed linear cascade facility are documented for mock catalytic and dry low NOx (DLN) combustion systems. Inlet turbulence levels range from about 1.0 percent for the mock catalytic combustor condition to 14 percent for the mock dry low NOx combustor system. Stanton number contours are presented at both turbulence conditions for Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2,000,000. Catalytic combustor endwall heat transfer shows the influence of the complex three-dimensional flow field, while the effects of individual vortex systems are less evident for the mock dry low NOx cases. Turbulence scales have been documented for both cases. Inlet boundary layers are relatively thin for both the mock catalytic and DLN combustor cases. Inlet boundary layer parameters are presented across the inlet passage for the three Reynolds numbers and both the mock catalytic and DLN combustor inlet cases. Both midspan and 95 percent span pressure contours are included. This research provides a well-documented database taken across a range of Reynolds numbers and turbulence conditions for assessment of endwall heat transfer predictive capabilities.

scholarly journals Stagnation Region Heat Transfer Augmentation at Very High Turbulence Levels

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
J. E. Kingery ◽  
F. E. Ames
Keyword(s):  
Heat Transfer ◽  
High Intensity ◽  
Gas Turbines ◽  
Large Scale ◽  
Large Diameter ◽  
Leading Edge ◽  
Test Surface ◽  
Bypass Transition ◽  
Stagnation Region ◽  
Heat Transfer Augmentation

Current land-based gas turbines are growing in size producing higher approach flow Reynolds numbers at the leading edge of turbine nozzles. These vanes are subjected to high intensity large scale turbulence. This present paper reports on the research which significantly expands the parameter range for stagnation region heat transfer augmentation due to high intensity turbulence. Heat transfer measurements were acquired over two constant heat flux test surfaces with large diameter leading edges (10.16 cm and 40.64 cm). The test surfaces were placed downstream from a new high intensity (17.4%) mock combustor and tested over an eight to one range in approach flow Reynolds number for each test surface. Stagnation region heat transfer augmentation for the smaller (ReD = 15,625–125,000) and larger (ReD = 62,500–500,000) leading edge regions ranged from 45% to 81% and 80% to 136%, respectively. These data also include heat transfer distributions over the full test surface compared with the earlier data acquired at six additional inlet turbulence conditions. These surfaces exhibit continued but more moderate acceleration downstream from the stagnation regions and these data are expected to be useful in testing bypass transition predictive approaches. This database will be useful to gas turbine heat transfer design engineers.

Effects of a Realistically Rough Surface on Vane Heat Transfer Including the Influence of Turbulence Condition and Reynolds Number

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
E. L. Erickson ◽  
F. E. Ames ◽  
J. P. Bons
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Rough Surface ◽  
Reynolds Numbers ◽  
Suction Surface ◽  
Average Roughness ◽  
Surface Distribution ◽  
Reynolds Analogy ◽  
Pressure Surface ◽  
Early Transition

Heat transfer distributions are experimentally acquired and reported for a vane with both a smooth and a realistically rough surface. Surface heat transfer is investigated over a range of turbulence levels (low (0.7%), grid (8.5%), aerocombustor (13.5%), and aerocombustor with decay (9.5%)) and a range of chord Reynolds numbers (ReC=500,000, 1,000,000, and 2,000,000). The realistically rough surface distribution was generated by Brigham Young University’s accelerated deposition facility. The surface is intended to represent a TBC surface that has accumulated 7500 h of operation with particulate deposition due to a mainstream concentration of 0.02 ppmw. The realistically rough surface was scaled by 11 times for consistency with the vane geometry and cast using a high thermal conductivity epoxy (k=2.1 W/m/K) to comply with the vane geometry. The surface was applied over the foil heater covering the vane pressure surface and about 10% of the suction surface. The 958×573 roughness array generated by Brigham Young on a 9.5×5.7 mm2 region was averaged to a 320×191 array for fabrication. The calculated surface roughness parameters of this scaled and averaged array included the maximum roughness, Rt=1.99 mm, the average roughness, Ra=0.25 mm, and the average forward facing angle, αf=3.974 deg. The peak to valley roughness, Rz, was determined to be 0.784 mm. The sand grain roughness of the surface (kS=0.466 mm) was estimated using a correlation offered by Bons (2005, “A Critical Assessment of Reynolds Analogy for Turbine Flows,” ASME J. Turbomach., 127, pp. 472–485). Based on estimates of skin friction coefficient using a turbulence correlation with the vane chord Reynolds numbers representative values for the surface’s roughness Reynolds number are 23, 43, and 80 for the three exit condition Reynolds numbers tested. Smooth vane heat transfer distributions exhibited significant laminar region augmentation with the elevated turbulence levels. Turbulence also caused early transition on the pressure surface for the higher Reynolds numbers. The rough surface had no significant effect on heat transfer in the laminar regions but caused early transition on the pressure surface in every case.

scholarly journals An Experimental Study on the Aerodynamics and the Heat Transfer of a Suction Side Film Cooled Large Scale Turbine Cascade

1999 ◽  
Author(s):  
Wolfgang Ganzert ◽  
Leonhard Fottner
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Film Cooling ◽  
Total Pressure ◽  
Large Scale ◽  
Suction Side ◽  
Surface Heat ◽  
Two Dimensional ◽  
Turbine Cascade ◽  
Surface Heat Transfer

As a part of a more complex research program systematic isothermal investigations on the aerodynamics and heat transfer of a large scale turbine cascade with suction side film cooling were carried out. The film cooling through a row of holes at forty percent chord length on the suction side was supplied by a large plenum chamber. Two injection geometries were hitherto tested and evaluated: cylindrical holes with thirty respectively fifty degrees axial inclination angle and no lateral inclination. Typical engine conditions for the Mach and Reynolds number as well as the inlet turbulence level were maintained. The aerodynamic studies are based on steady state pressure measurements. The static profile pressure distribution together with oil-and-dye flow visualisation gives information on the surface flow conditions and boundary layer development especially in the near hole region. The measured data also comprise local and integral total pressure loss coefficients obtained by pressure probe traversing at mid span downstream of the cascade. The heat transfer examination set-up is based on the steady state liquid crystal technique using a compound of a thermochromic sheet combined with an electrical surface heating layer attached on an adiabatic blade corpus. Two dimensional pseudo colour plots are used for the documentation of the local surface heat transfer coefficient distribution and hot spot estimation. Laterally averaged and statistically analysed data of the surface heat transfer is applied in overall heat transfer examinations. All this data is used for a joint aerodynamic flow and surface heat transfer optimisation of a blowing configuration in suction side film cooled turbine cascade. The most important conclusions can be summarised as follows: Aiming at an optimised design of cylindrical film cooling configurations the axial inclination of the holes should be kept low thus diminishing the suction peak value at the cooling position in the profile pressure distribution and decreasing the mainstream deceleration area upstream of the jets. This also leads to reduced total pressure losses. Through the high influence of the blowing on the aerodynamics the flow in the near hole mixing region is highly three-dimensional. This shows significant effects in the two-dimensional surface distribution and the laterally averaged heat transfer coefficient. Oil-and-dye pictures confirm the observations qualitatively.

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