Assessment of Steady State PSP, TSP, and IR Measurement Techniques for Flat Plate Film Cooling

2005 ◽  
Author(s):  
Lesley M. Wright ◽  
Zhihong Gao ◽  
Trent A. Varvel ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Film Cooling ◽  
Measurement Techniques ◽  
Ir Thermography ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
State Measurement ◽  
Compound Angle ◽  
Steady State Measurement

Several steady state measurement techniques are used to measure the film cooling effectiveness on a flat plate. Pressure sensitive paint (PSP), temperature sensitive paint (TSP), and infrared (IR) thermography are used to measure the film cooling effectiveness. To compare these measurement techniques, a single row of cylindrical holes, with a compound angle, are used. Seven holes (D = 4 mm) are equally spaced 12 mm apart, and the hole length-to-diameter ratio is 9.92. The axial angle (θ) of the holes is 30°, and the compound angle (β) is 45°. In addition to evaluating the various measurement techniques the effect of the coolant blowing ratio is considered; effectiveness measurements are taken for blowing ratios, M, of 0.4, 0.6, 1.2, and 1.8. The effect of mainstream turbulence intensity is considered with the addition of a turbulence grid to the low speed wind tunnel. Of the three steady state measurement techniques considered in this study, PSP demonstrates the most promise for the measurement of the film cooling effectiveness. Because PSP is a mass transfer technique, film effectiveness measurements can be readily obtained near the film cooling holes. Although the heat transfer techniques of TSP and IR thermography are more desirable than traditional thermocouples or liquid crystal thermography, the applicability of measurements near the holes is questionable due to conduction problems associated with steady state heat transfer techniques.

Assessment of Steady State PSP and Transient Ir Measurement Techniques for Leading Edge Film Cooling

2005 ◽  
Author(s):  
Zhihong Gao ◽  
Lesley M. Wright ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Film Cooling ◽  
Measurement Techniques ◽  
Turbine Blades ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Stagnation Line ◽  
Film Cooling Effectiveness ◽  
Film Cooling Holes

Film cooling is commonly used on the leading edge of turbine blades to protect the blade surface from hot mainstream gases in the turbine. Obtaining detailed film cooling effectiveness distributions on the leading edge can be challenging. This paper considers two measurement techniques which can be applied to the leading edge (modeled by a cylinder) to obtain detailed distributions of the film effectiveness. A steady state pressure sensitive paint (PSP) technique and a transient infrared (IR) thermography technique are used to obtain detailed film cooling effectiveness distributions on the cylinder. The cylinder, 7.62 cm in diameter, is placed in a low speed wind tunnel, with the mainstream flow having a Reynolds number of 100,900 (based on the cylinder diameter). The cylinder has two rows of film cooling holes located at ±15° from the cylinder’s stagnation line. The pitch-to-diameter ratio of the film holes is 4, and holes are inclined 30° in spanwise direction. PSP continues to show promise for film cooling effectiveness measurements. Detailed distributions can be obtained near the film cooling holes because this technique relies on mass transfer rather than heat transfer. In order to reduce the error caused by conduction in heat transfer experiments, transient measurement techniques are favorable. Transient IR measurements are taken, and film cooling effectiveness is determined on the cylinder’s surface. Although the effect of conduction is reduced with the transient IR technique (compared to a steady state heat transfer experiment), heat conduction through the cylinder has not been eliminated (or even minimized). Without correction, the results obtained from transient heat transfer experiments must be used cautiously. For this reason, PSP is developing a niche within the gas turbine community for detailed film cooling effectiveness measurements.

Effect of Internal Crossflow Velocity on Film Cooling Effectiveness: Part II — Compound Angle Shaped Holes

2017 ◽  
Author(s):  
John W. McClintic ◽  
Joshua B. Anderson ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
Zachary D. Webster
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Film Cooling ◽  
Velocity Ratio ◽  
Injection Rate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Crossflow Velocity ◽  
Film Cooling Holes ◽  
Compound Angle

In gas turbine engines, film cooling holes are commonly fed with an internal crossflow, the magnitude of which has been shown to have a notable effect on film cooling effectiveness. In Part I of this study, as well as in a few previous studies, the magnitude of internal crossflow velocity was shown to have a substantial effect on film cooling effectiveness of axial shaped holes. There is, however, almost no data available in the literature that shows how internal crossflow affects compound angle shaped film cooling holes. In Part II, film cooling effectiveness, heat transfer coefficient augmentation, and discharge coefficients were measured for a single row of compound angle shaped film cooling holes fed by internal crossflow flowing both in-line and counter to the span-wise direction of coolant injection. The crossflow-to-mainstream velocity ratio was varied from 0.2–0.6 and the injection velocity ratio was varied from 0.2–1.7. It was found that increasing the magnitude of the crossflow velocity generally caused degradation of the film cooling effectiveness, especially for in-line crossflow. An analysis of jet characteristic parameters demonstrated the importance of crossflow effects relative to the effect of varying the film cooling injection rate. Heat transfer coefficient augmentation was found to be primarily dependent on injection rate, although for in-line crossflow, increasing crossflow velocity significantly increased augmentation for certain conditions.

Influence of Two Rows Compound and Simple Angle Holes in Inline and/or Staggered on Film Cooling and Heat Transfer

2005 ◽  
Author(s):  
Bilal Y. Maiteh
Keyword(s):  
Heat Transfer ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Pressure Gradients ◽  
Heat Transfer Characteristics ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Mainstream Flow ◽  
Favorable Pressure Gradient ◽  
Compound Angle

This paper describes the results of an experimental investigation into the effect of the mainstream flow history on the film cooling effectiveness and the heat transfer characteristics from the combination of one row of simple angle holes and one row of compound angle holes. The mainstream flow history includes: favorable pressure gradient factors in the range −1.11 × 10−6 to +1.11 × 10−6 and turbulence intensity in the range 0.3% to 4.7%. The presence of favorable pressure gradients in the flow reduces the film cooling protection of the surfaces from both compound angle holes or combination of simple and compound angle holes, while the presence of adverse pressure gradients increases the film cooling effectiveness at low blowing rate and decreases it at high blowing rate. Increasing the turbulence intensity reduces the film cooling effectiveness from compound angle holes or combination of simple and compound angle holes.

Heat Transfer and Film Cooling Effectiveness in a Linear Airfoil Cascade

1997 ◽  
Vol 119 (2) ◽  
pp. 302-309 ◽  
Author(s):  
N. Abuaf ◽  
R. Bunker ◽  
C. P. Lee
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Film Cooling ◽  
Leading Edge ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Linear Cascade ◽  
Heat Transfer Coefficients

A warm (315°C) wind tunnel test facility equipped with a linear cascade of film cooled vane airfoils was used in the simultaneous determination of the local gas side heat transfer coefficients and the adiabatic film cooling effectiveness. The test rig can be operated in either a steady-state or a transient mode. The steady-state operation provides adiabatic film cooling effectiveness values while the transient mode generates data for the determination of the local heat transfer coefficients from the temperature–time variations and of the film effectiveness from the steady wall temperatures within the same aerothermal environment. The linear cascade consists of five airfoils. The 14 percent cascade inlet free-stream turbulence intensity is generated by a perforated plate, positioned upstream of the airfoil leading edge. For the first transient tests, five cylinders having roughly the same blockage as the initial 20 percent axial chord of the airfoils were used. The cylinder stagnation point heat transfer coefficients compare well with values calculated from correlations. Static pressure distributions measured over an instrumented airfoil agree with inviscid predictions. Heat transfer coefficients and adiabatic film cooling effectiveness results were obtained with a smooth airfoil having three separate film injection locations, two along the suction side, and the third one covering the leading edge showerhead region. Near the film injection locations, the heat transfer coefficients increase with the blowing film. At the termination of the film cooled airfoil tests, the film holes were plugged and heat transfer tests were conducted with non-film cooled airfoils. These results agree with boundary layer code predictions.

Heat Transfer and Film Cooling Effectiveness in a Linear Airfoil Cascade

1995 ◽  
Author(s):  
N. Abuaf ◽  
R. Bunker ◽  
C. P. Lee
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Film Cooling ◽  
Leading Edge ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Linear Cascade ◽  
Heat Transfer Coefficients

A warm (315 C) wind tunnel test facility equipped with a linear cascade of film cooled vane airfoils was used in the simultaneous determination of the local gas side heat transfer coefficients and the adiabatic film cooling effectiveness. The test rig can be operated in either a steady-state or a transient mode. The steady-state operation provides adiabatic film cooling effectiveness values while the transient mode generates data for the determination of the local heat transfer coefficients from the temperature-time variations and of the film effectiveness from the steady wall temperatures within the same aero-thermal environment. The linear cascade consists of five airfoils. The 14% cascade inlet free stream turbulence intensity is generated by a perforated plate, positioned upstream of the airfoil leading edge. For the first transient tests, five cylinders having roughly the same blockage as the initial 20% axial chord of the airfoils were used. The cylinder stagnation point heat transfer coefficients compare well with values calculated from correlations. Static pressure distributions measured over an instrumented airfoil agree with inviscid predictions. Heat transfer coefficients and adiabatic film cooling effectiveness results were obtained with a smooth airfoil having three separate film injection locations, two along the suction side, and the third one covering the leading edge showerhead region. Near the film injection locations, the heat transfer coefficients increase with the blowing film. At the termination of the film cooled airfoil tests, the film holes were plugged and heat transfer tests were conducted with non-film cooled airfoils. These results agree with boundary layer code predictions.

Application of Steady State and Transient IR-Thermography Measurements to Film Cooling Experiments for a Row of Shaped Holes

2005 ◽  
Author(s):  
Dennis Brauckmann ◽  
Jens von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Film Cooling ◽  
Measured Temperature ◽  
Ir Thermography ◽  
Adiabatic Wall ◽  
Test Plate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
The Heat Transfer Coefficient

This paper presents experimental investigations for the measurement of the adiabatic film cooling effectiveness as well as the heat transfer coefficient distribution in film cooling experiments with a row of fanshaped holes on a flat plate. The temperature distribution on the flat plate is measured using infrared-thermography (IR). Adiabatic wall effectiveness data are obtained using a high-temperature plastic material. Although a low thermal conductivity material is used, the measured temperature distribution is not identical with the adiabatic temperature distribution. The measured temperature field shows influences of 3D heat conduction inside the test plate. The effects of the heat conduction inside the test plate are modeled using the FE-method to re-evaluate the adiabatic wall temperature and to calculate the coolant gas exit temperature, which is used for the adiabatic film cooling effectiveness. For the measurement of the heat transfer coefficient ratio with and without film cooling (hf/h0) a transient method is used. Temperature transients on the test surface are initiated by switching the coolant flow and are recorded using IR-thermography. The measured wall temperature histories are converted into heat flux values assuming a semi-infinite wall model during the experiment.

Influence of Compound Angle on Adiabatic Film Cooling Effectiveness and Heat Transfer Coefficient for a Row of Shaped Film Cooling Holes

2005 ◽  
Author(s):  
Dennis Brauckmann ◽  
Jens von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Test Plate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Film Cooling Holes ◽  
Compound Angle ◽  
The Heat Transfer Coefficient

The measurement of adiabatic film cooling effectiveness data and heat transfer coefficient data for a row of fanshaped film cooling holes at different compound angles is presented in this paper. The measurements are performed at engine-like temperature ratios in a hot gas test facility on a flat test plate. For the film cooling geometry, a row of five laidback-fanshaped holes was used. The temperature distribution on the flat plate is measured using infrared-thermography (IR). Steady state measurements are used to obtain the film cooling effectiveness. For the determination of the heat transfer coefficient ratio with and without film cooling on the test plate, a transient measurement technique is applied. Results for both the adiabatic film cooling effectiveness and the heat transfer coefficient ratio are given. The influence of different blowing ratios on the injection with compound angles of 0°, 30° and 45° will be discussed. From this study, the increasing compound angle showed only small effects on the pitch-wise lateral averaged adiabatic film cooling effectiveness but increased the heat transfer on the film cooled flat plate with coolant injection.

Derivation of 2-D Empirical Correlations for Film-Cooling Effectiveness and Heat Transfer Augmentation From Spanwise Averaged Data and Correlations

2013 ◽  
Author(s):  
Peter T. Ingram ◽  
Savas Yavuzkurt
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Heat Transfer Augmentation ◽  
Cylindrical Holes ◽  
Compound Angle

In existing gas turbine heat transfer literature, there are several correlations developed for the spanwise-averaged film-cooling effectiveness and heat transfer augmentation for inline injection on flat plates. More accurate and detailed predictions of film-cooling performance, particularly 3-D solid temperatures are needed for design purposes. 2-D correlations where effectiveness and heat transfer augmentation are functions of streamwise and spanwise directions are necessary to satisfy this need. Previously developed 2-D correlations for single row of cylindrical holes with inline injection have been improved to include the effects of shaped holes such as hole breakthrough width (t/D) and area ratio (AR). The correlations are improved to better match spanwise effectiveness of a single row of shaped cooling holes using data and spanwise-averaged correlations. Modifications to the correlations to improve application to compound injection (β) have been implemented. The blowing ratio is modified to account for the compound angle effect. The spanwise location of maximum film-cooling effectiveness and heat transfer augmentation are obtained as functions of the streamwise coordinate. Iterative Conjugate Heat Transfer Reduced Order Film Model (ICHT-ROFM) was used to obtain 3-D conjugate temperature distribution in film cooled solids. The developed correlations predicted a relative cooling effect in the near hole region for shaped holes (24 K) and for compound angle injection (20K) compared to cylindrical holes. Spanwise variations in the solid temperature in the near hole region are between 40–50K for a temperature difference of 250K between the surface and the main stream and are quite significant, showing the need for 3-D simulations. Shaped and compound angle holes increase this temperature difference due to the increased cooling. The comparisons of solid temperatures for conjugate and non-conjugate heat transfer cases show about 13–18K or 8–10% of the local temperature difference of 180K. Therefore it can be concluded that the calculations of 3-D temperature distributions using conjugate heat transfer are very important for design purposes.

Heat Transfer Coefficients and Film Cooling Effectiveness of Transonic Turbine Vane Suction Surface Using TSP Technique

2016 ◽  
Author(s):  
Chao-Cheng Shiau ◽  
Nafiz H. K. Chowdhury ◽  
Shang-Feng Yang ◽  
Je-Chin Han ◽  
Alexander MirzaMoghadam ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Suction Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Heat Transfer Coefficients ◽  
Compound Angle

This paper experimentally studies the effect of transonic flow on local heat transfer coefficients and film cooling effectiveness distributions of a turbine vane’s suction surface with compound-angle shaped-hole configuration. A Temperature Sensitive Paint (TSP) method is used to determine the local heat transfer coefficients and film cooling effectiveness simultaneously. Tests were performed in a five-vane annular-sector cascade blow-down facility. The exit Mach numbers are controlled to be 0.7 and 0.9, from subsonic to transonic conditions. Compressed air is used as coolant with a coolant-to-mainstream density ratio 0.91 on film cooling and heat transfer study. Three averaged coolant-to-mainstream blowing ratios in the range, 0.7, 1.0, and 1.6 are investigated. The test vane features three rows of radial-angle cylindrical holes around the leading edge, and two rows of compound-angle shaped holes on the suction side. Effects of blowing ratio and exit Mach number on the vane suction surface heat transfer and film cooling effectiveness distributions are obtained, and the results are presented and explained in this investigation.

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