FILM COOLING EFFECTIVENESS OF DISCRETE HOLES MEASURED BY MASS TRANSFER AND LASER INTERFEROMETER

1982 ◽  
Author(s):  
Shao-Yen Ko ◽  
Deng-Ying Liu ◽  
Yong-Qing Yao ◽  
Jing Li ◽  
Fu-Kang Tsou
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Laser Interferometer ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

Measured Film Cooling Effectiveness of Three Multihole Patterns

2005 ◽  
Vol 128 (2) ◽  
pp. 192-197 ◽  
Author(s):  
Yuzhen Lin ◽  
Bo Song ◽  
Bin Li ◽  
Gaoen Liu
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Film Cooling ◽  
Row Spacing ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Analogy Method ◽  
Blowing Ratio ◽  
The Third ◽  
Coolant Injection

As an advanced cooling scheme to meet increasingly stringent combustor cooling requirements, multihole film cooling has received considerable attention. Experimental data of this cooling scheme are limited in the open literature in terms of different hole patterns and blowing ratios. The heat-mass transfer analogy method was employed to measure adiabatic film cooling effectiveness of three multihole patterns. Three hole patterns differed in streamwise row spacing (S), spanwise hole pitch (P), and hole inclination angle (α), with the first pattern S∕P=2 and α=30°, the second S∕P=1 and α=30°, and the third S∕P=2 and α=150°. Measurements were performed at different blow ratios (M=1-4). Streamwise coolant injection offers high cooling protection for downstream rows. Reverse coolant injection provides superior cooling protection for initial rows. The effect of blowing ratio on cooling effectiveness is small for streamwise injection but significant for reversion injection.

Film Cooling Downstream of a Row of Discrete Holes With Compound Angle

2000 ◽  
Vol 123 (2) ◽  
pp. 222-230 ◽  
Author(s):  
R. J. Goldstein ◽  
P. Jin
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Film Cooling ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Mass Transfer Coefficients ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Compound Angle

A special naphthalene sublimation technique is used to study the film cooling performance downstream of one row of holes of 35 deg inclination angle and 45 deg compound angle with 3d hole spacing and relatively small hole length to diameter ratio (6.3). Both film cooling effectiveness and mass/heat transfer coefficients are determined for blowing rates from 0.5 to 2.0 with density ratio of unity. The mass transfer coefficient is measured using pure air film injection, while the film cooling effectiveness is derived from comparison of mass transfer coefficients obtained following injection of naphthalene-vapor-saturated air with that of pure air injection. This technique enables one to obtain detailed local information on film cooling performance. General agreement is found in local film cooling effectiveness when compared with previous experiments. The laterally averaged effectiveness with compound angle injection is higher than that with inclined holes immediately downstream of injection at a blowing rate of 0.5 and is higher at all locations downstream of injection at larger blowing rates. A large variation of mass transfer coefficients in the lateral direction is observed in the present study. At low blowing rates of 0.5 and 1.0, the laterally averaged mass transfer coefficient is close to that of injection without compound angle. At the highest blowing rate used (2.0), the asymmetric vortex motion under the jets increases the mass transfer coefficient drastically ten diameters downstream of injection.

Heat (Mass) Transfer and Film Cooling Effectiveness With Injection Through Discrete Holes: Part II—On the Exposed Surface

1995 ◽  
Vol 117 (3) ◽  
pp. 451-460 ◽  
Author(s):  
H. H. Cho ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Heat Mass Transfer ◽  
Saturated Vapor ◽  
Back Surface ◽  
Exposed Surface ◽  
Transfer Coefficients ◽  
Lateral Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

The heat (mass) transfer coefficient and the film cooling effectiveness are obtained from separate tests using pure air and naphthalene-saturated vapor injected through circular holes into a crossflow of air. The experiments indicate that Sherwood numbers around the injection hole are up to four times those on a flat plate (without injection holes) due to the interaction of the jets and the mainstream. The mass transfer around the injection holes is dominated by formations of horseshoe, side, and kidney vortices, which are generated by the jet and crossflow interaction. For an in-line array of holes, the effectiveness is high and uniform in the streamwise direction but has a large variation in the lateral direction. The key parameters, including transfer coefficients on the back surface (Part I), inside the hole (Part I), and on the exposed surfaces, and the effectiveness on the exposed surface, are obtained so that the wall temperature distribution near the injection holes can be determined for a given heat flux condition. This detailed information will also aid the numerical modeling of flow and mass/heat transfer around film cooling holes.

scholarly journals Film Cooling on a Gas Turbine Rotor Blade

1991 ◽  
Author(s):  
Kenichiro Takeishi ◽  
Sunao Aoki ◽  
Tomohiko Sato ◽  
Keizo Tsukagoshi
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Rotor Blade ◽  
Turbine Rotor ◽  
Suction Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Turbine Rotor Blade ◽  
Pressure Surface ◽  
Rotating Blade

The film cooling effectiveness on a low-speed stationary cascade and the rotating blade has been measured by using a heat-mass transfer analogy. The film cooling effectiveness on the suction surface of the rotating blade fits well with that on the stationary blade, but a low level of effectiveness appears on the pressure surface of the rotating blade. In this paper, typical film cooling data will be presented and film cooling on a rotating blade is discussed.

Film Cooling Effectiveness and Mass/Heat Transfer Coefficient Downstream of One Row of Discrete Holes

1999 ◽  
Vol 121 (2) ◽  
pp. 225-232 ◽  
Author(s):  
R. J. Goldstein ◽  
P. Jin ◽  
R. L. Olson
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Density Ratio ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness

A special naphthalene sublimation technique is used to study the film cooling performance downstream of one row of holes of 35 deg inclination angle with 3d hole spacing and relatively small hole length to diameter ratio (L/d = 6.3). Both film cooling effectiveness and mass/heat transfer coefficient are determined for blowing rates from 0.5 to 2.0 with density ratio of 1.0. The mass transfer coefficient is measured using pure air film injection, while the film cooling effectiveness is derived from comparison of mass transfer coefficients obtained following injection of naphthalene-vapor-saturated air with those from pure air injection. This technique enables one to obtain detailed local information on film cooling performance. The laterally averaged and local film cooling effectiveness agree with previous experiments. The difference between mass/heat transfer coefficients and previous heat transfer results indicates that conduction error may play an important role in the earlier heat transfer measurements.

The Film Cooling Effectiveness of Double Rows of Holes

1980 ◽  
Vol 102 (3) ◽  
pp. 601-606 ◽  
Author(s):  
W. O. Afejuku ◽  
N. Hay ◽  
D. Lampard
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Coolant Flow ◽  
Row Spacing ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

The film cooling effectiveness provided by two rows of holes separated by a range of distances has been studied experimentally using a mass transfer technique. The blowing rates at the two rows were varied independently. The results are presented in forms suitable for design purposes. Spanwise and area averaged effectivenesses are given for a range of blowing rates. Thus optimum blowing rates for a given row spacing and total coolant flow can be established. Comparisons with a simple superposition theory show that this can be used with safety for design purposes if the holes in the two rows are staggered, but restrictions apply if they are in-line.

Film Cooling on a Gas Turbine Rotor Blade

1992 ◽  
Vol 114 (4) ◽  
pp. 828-834 ◽  
Author(s):  
K. Takeishi ◽  
S. Aoki ◽  
T. Sato ◽  
K. Tsukagoshi
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Rotor Blade ◽  
Turbine Rotor ◽  
Suction Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Turbine Rotor Blade ◽  
Pressure Surface ◽  
Rotating Blade

The film cooling effectiveness on a low-speed stationary cascade and the rotating blade has been measured by using a heat-mass transfer analogy. The film cooling effectiveness on the suction surface of the rotating blade fits well with that on the stationary blade, but a low level of effectiveness appears on the pressure surface of the rotating blade. In this paper, typical film cooling data will be presented and film cooling on a rotating blade is discussed.

scholarly journals Film Cooling Effectiveness and Heat/Mass Transfer Coefficient Measurement Around a Conical-Shaped Hole With a Compound Angle Injection

1999 ◽  
Author(s):  
H. H. Cho ◽  
D. H. Rhee ◽  
B. G. Kim
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Heat Mass Transfer ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Shaped Hole ◽  
Hole Geometry ◽  
Compound Angle

The present study investigates local film cooling effectiveness values and heat/mass transfer coefficients around a conical-shaped film cooling hole with compound angle orientations. Three types of film cooling hole geometry are compared in this study; one is cylindrical hole geometry with constant cross section and the others are shaped hole geometries with conically-enlarged hole exits. The shaped holes have cylindrical passage sections at the hole inlet region to obtain a certain pressure drop through the holes. One shaped hole expands 4° in all directions from the middle of hole to the exit. The other shaped hole has the tilted center-line by 4° between the conical and metering holes and is enlarged by 8° to downstream side. The hole area ratios of the exit to the inlet are 2.55 and 2.48, respectively. The compound-angled film cooling jet is ejected through the single holes, which are inclined at 30° to the surface based on the metering hole and are rotatable in lateral direction from 0° to 90°. The blowing rates are changed from 0.5 to 2.0. The naphthalene sublimation technique is used to determine local heat/mass transfer coefficients and local adiabatic/impermeable wall film cooling effectiveness around the injection hole. The results indicate that the injected jet protects the surface effectively with low blowing rates and spreads more widely with the compound angle injections than the axial injection. For the shaped hole enlarged by 4° in all directions, the penetration of jet is reduced and higher cooling performance is obtained even at relatively high blowing rates because the increased hole exit area reduces hole exit velocity. Furthermore, the film cooling effectiveness is fairly uniform near the hole due to the wide lateral spreading of coolant with the expanded cooling hole exit.

Film Cooling Downstream of a Row of Discrete Holes With Compound Angle

2000 ◽  
Author(s):  
R. J. Goldstein ◽  
P. Jin
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Film Cooling ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Mass Transfer Coefficients ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Compound Angle

A special naphthalene sublimation technique is used to study the film cooling performance downstream of one row of holes of 35° inclination angle and 45° compound angle with 3 diameter hole spacing and relatively small hole length to diameter ratio (6.3). Both film cooling effectiveness and mass/heat transfer coefficients are determined for blowing rates from 0.5 to 2.0 with density ratio of unity. The mass transfer coefficient is measured using pure air film injection, while the film cooling effectiveness is derived from comparison of mass transfer coefficients obtained following injection of naphthalene-vapor-saturated air with that of pure air injection. This technique enables one to obtain detailed local information on film cooling performance. General agreement is found in local film cooling effectiveness when compared with previous experiments. The laterally-averaged effectiveness with compound angle injection is higher than that with inclined holes immediately downstream of injection at a blowing rate of 0.5 and is higher at all locations downstream of injection at larger blowing rates. A large variation of mass transfer coefficients in the lateral direction is observed in the present study. At low blowing rates of 0.5 and 1.0, the laterally-averaged mass transfer coefficient is close to that of injection without compound angle. At the highest blowing rate used (2.0), the asymmetrical vortex motion under the jets increases the mass transfer coefficient drastically ten diameters downstream of injection.

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