A comprehensive investigation of the effect of various tip sealing geometries is presented on the blade tip leakage flow and associated heat transfer of a scaled up HPT turbine blade in a low-speed wind tunnel facility. The linear cascade is made of four blades with the two corner blades acting as guides. The tip section of a HPT first stage rotor blade is used to fabricate the two-dimensional blade. The wind tunnel accommodates an 116 deg turn for the blade cascade. The mainstream Reynolds number based on the axial chord length at cascade exit is $4.83×105.$ The upstream wake effect is simulated with a spoked wheel wake generator placed upstream of the cascade. A turbulence grid placed even farther upstream generates the required freestream turbulence of 4.8%. The center blade has a tip clearance gap of 1.5625% with respect to the blade span. Static pressure measurements are obtained on the blade surface and the shroud. The effect of crosswise trip strips to reduce leakage flow and associated heat transfer is investigated with strips placed along the leakage flow direction, against the leakage flow and along the chord. Cylindrical pin fins and pitch variation of strips over the tip surface are also investigated. Detailed heat transfer measurements are obtained using a steady-state HSI-based liquid crystal technique. The effect of periodic unsteady wake effect is also investigated by varying the wake Strouhal number from 0. to 0.2, and to 0.4. Results show that the trip strips placed against the leakage flow produce the lowest heat transfer on the tips compared to all the other cases with a reduction between 10–15% compared to the plain tip. Results also show that the pitch of the strips has a small effect on the overall reduction. Cylindrical pins fins and strips along the leakage flow direction do not decrease the heat transfer coefficients and in some cases enhance the heat transfer coefficients by as much as 20%.

1.
Bindon
,
J. P.
,
1989
, “
The Measurement and Formation of Tip Clearance Loss
,”
ASME Journal of Turbomach.
, ,
111
, pp.
257
263
.
2.
Morphis, G., and Bindon, J. P., 1988, “The Effect of Relative Motion, Blade Edge Radius and Gap Size on the Blade Tip Pressure Distribution in an Annular Turbine Cascade With Clearance,” AMSE Paper 88-GT-256.
3.
Yaras
,
M.
,
Yingkang
,
Z.
, and
Sjolander
,
S. A.
,
1989
, “
Flow Field in the Tip Gap of a Planar Cascade of Turbine Blades
,”
ASME Journal of Turbomach.
,
111
, pp.
276
283
.
4.
Yamamoto
,
A.
,
1989
, “
Endwall Flow/Loss Mechanisms in a Linear Turbine Cascade With Blade Tip Clearance
,”
ASEM Journal of Turbomach.
,
111
, pp.
264
275
.
5.
Kaiser, I., and Bindon, J. P., 1997, “The Effect of Tip Clearance on the Development of Loss Behind a Rotor and a Subsequent Nozzle,” ASME Paper 97-GT-53.
6.
Mayle, R. E., and Metzger, D. E., 1982, “Heat Transfer at the Tip of an Unshrouded Turbine Blade,” Proceedings of the 7th International Heat Transfer Conference, 3, pp. 87–92.
7.
Metzger
,
D. E.
,
Bunker
,
R. S.
, and
Chyu
,
M. K.
,
1989
, “
Cavity Heat Transfer on a Transverse Grooved Wall in a Narrow Flow Channel
,”
J. Heat Transfer
,
111
, pp.
73
79
.
8.
Chyu
,
M. K.
,
Moon
,
H. K.
, and
Metzger
,
D. E.
,
1989
, “
Heat Transfer in the Tip Region of Grooved Turbine Blades
,”
ASME Journal of Turbomach.
,
111
, pp.
131
138
.
9.
Metzger, D. E., Dunn, M. G., and Hah, C., 1990, “Turbine Tip and Shroud Heat Transfer,” ASME Paper 90-GT-333.
10.
Yang, T. T., and Diller, T. E., 1995, “Heat Transfer and Flow for a Grooved Turbine Blade Tip in a Transonic Cascade,” ASME Paper 95-WA/HT-29.
11.
Bunker
,
R. S.
,
Bailey
,
J. C.
, and
Ameri
,
A. A.
,
1999
, “
Heat Transfer and Flow on the First Stage Blade Tip of a Power Generation Gas Turbine: Part I—Experimental Results
,”
ASME Journal of Turbomach.
122
, pp.
263
271
.
12.
Ameri
,
A. A.
, and
Bunker
,
R. S.
,
1999
, “
Heat Transfer and Flow on the First Stage Blade Tip of a Power Generation Gas Turbine: Part II—Simulation Results
,”
ASME Journal of Turbomach.
,
122
, pp.
272
277
.
13.
Azad, Gm. S., Han, J. C., and Teng, S., 2000, “Heat Transfer and Pressure Distributions on a Gas Turbine Blade Tip,” ASME Paper 2000-GT-194.
14.
Azad, G. S., Han, J. C., and Boyle, R. J., 2000, “Heat Transfer and Flow on the Squealer Tip of a Gas Turbine Blade,” ASME Paper 2000-GT-195.
15.
Bunker, R. S., and Bailey, J. C., 2000, “An Experimental Study of Heat Transfer and Flow on a Gas Turbine Blade Tip With Various Tip Leakage Sealing Methods,” Proceedings of the 4th HMT/ASME Heat and Mass Transfer Conference, Paper No. HMT2000-055, ASME, New York, pp. 411–416.
16.
Bunker, R. S., and Bailey, J. C., 2000, “Blade Tip heat Transfer and Flow with Chordwise Sealing Strips,” International Symposium on Transport Phenomena and Dynamics of Rotating Machinery (ISROMAC), Honolulu, HI, pp. 548–555.
17.
Bunker, R. S., and Bailey, J. C., 2001, “Effect of Squealer Cavity Depth and Oxidation on Turbine Blade Tip Heat Transfer,” International Gas Turbine and Aeroengine Congress and Exposition, New Orleans, LA, June.
18.
Azad, G. S., Han, J. C., Bunker, R. S., and Lee, C. P., 2001, “Effect of Squealer Geometry Arrangement on Gas Turbine Blade Tip Heat Transfer,” ASME Paper IMECE2001/HTD-2431.
19.
Dunn, M. G., and Haldeman, C. W., 2000, “Time-Averaged Heat Flux for a Recessed Tip, Lip and Platform of a Transonic Turbine Blade,” ASME Paper 2000-GT-0197.
20.
Wittig, S., Schulz, A., Dullenkopf, K., and Fairbank, J., 1988, “Effects of Free-Stream Turbulence and Wake Characteristics on the Heat Transfer Along a Cooled Gas Turbine Blade,” ASME Paper 88-GT-179.
21.
Han
,
J. C.
,
Zhang
,
L.
, and
Ou
,
S.
,
1993
, “
Influence of Unsteady Wake on Heat Transfer Coefficient From a Gas Turbine Blade
,”
J. Heat Transfer
,
115
, pp.
904
911
.
22.
Teng
,
S.
,
Han
,
J. C.
, and
Azad
,
Gm. S.
, 2001, “Detailed Heat Transfer Coefficient Distributions on a Large Scale Gas Turbine Blade Tip,” ASME J. Heat Transfer, 123.
23.
Camci, C., Kim, K., and Hippensteele, S. A., 1991, “A New Hue Capturing Technique for Quantitative Interpretation of Liquid Crystal Images Used in Convective Heat Transfer Studies,” ASME Paper 91-GT-277.
24.
Kline
,
S. J.
, and
McClintock
,
F. A.
,
1953
, “
Describing Uncertainties in Single Sample Experiments
,”
Mechanical Engineering
,
75
, pp.
3
8
.
You do not currently have access to this content.