Measurements of Heat Transfer Coefficients and Friction Factors in Rib-Roughened Channels Simulating Leading-Edge Cavities of a Modern Turbine Blade
Author:
Taslim M. E.1, Li T.1, Spring S. D.2
Affiliation:
1. Department of Mechanical Engineering, Northeastern University, Boston, MA 02115 2. GE Aircraft Engines, Lynn, MA 02190
Abstract
Leading edge cooling cavities in modern gas turbine blades play an important role in maintaining the leading edge temperature at levels consistent with airfoil design life. These cavities often have a complex cross-sectional shape to be compatible with the external contour of the blade at the leading edge. A survey of many existing geometries shows that, for analytical as well as experimental analyses, such cavities can be simplified in shape by a four-sided polygon with one curved side similar to the leading edge curvature, a rectangle with one semicircular side (often the smaller side) or a trapezoid, the smaller base of which is replaced by a semicircle. Furthermore, to enhance the heat transfer coefficient in these cavities, they are mostly roughened on three sides with ribs of different geometries. Experimental data on friction factors and heat transfer coefficients in such cavities are rare if not nonexistent. A liquid crystal technique was used in this experimental investigation to measure heat transfer coefficients in six test sections representing the leading-edge cooling cavities. Both straight and tapered ribs were configured on the two opposite sidewalls in a staggered arrangement with angles of attack to the mainstream flow, α of 60 and 90 deg. The ribs on the curved surface were of constant cross section with an angle of attack 90 deg to the flow. Heat transfer measurements were performed on the straight sidewalls, as well as on the round surface adjacent to the blade leading edge. Effects such as rib angle of attack to the mainstream flow and constant versus tapered rib cross-sectional areas were also investigated. Nusselt numbers, friction factors, and thermal performances are reported for nine rib geometries in six test sections.
Publisher
ASME International
Subject
Mechanical Engineering
Reference27 articles.
1. Burggraf, F., 1970, “Experimental Heat Transfer and Pressure Drop With Two Dimensional Turbulence Promoters Applied to Two Opposite Walls of a Square Tube,” Augmentation of Convective Heat and Mass Transfer, A. E. Bergles and R. L. Webb, eds., ASME, New York, pp. 70–79. 2. Chandra
P. R.
, HanJ. C., and LauS. C., 1988, “Effect of Rib Angle on Local Heat/Mass Transfer Distribution in a Two-Pass Rib-Roughened Channel,” ASME JOURNAL OF TURBOMACHINERY, Vol. 110, pp. 233–241. 3. Chandra
P. R.
, and HanJ. C., 1989, “Pressure Drop and Mass Transfer in Two-Pass Ribbed Channels,” Journal of Thermophysics, Vol. 3, No. 3, pp. 315–319. 4. Dittus, F. W., and Boelter, L. M. K., 1930, Publications in Engineering, Vol. 2, No. 13, University of California, Berkeley, CA, pp. 443–461. 5. Dutta, S., and Han, J. C., 1994, “Effect of Model Orientation on Local Heat Transfer in a Rotating Two-Pass Smooth Triangular Duct,” presented at the ASME Winter Annual Meeting.
Cited by
26 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|