Measurements of heat transfer coefficients and friction factors in rib-roughened channels simulating leading-edge cavities of a modern turbine blade

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Journal of Turbomachinery

DOI:https://doi.org/10.1115/1.2841164· OSTI ID:516732

Taslim, M E; Li, T ^[1]; Spring, S D ^[2]

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1. Northeastern Univ., Boston, MA (United States). Dept. of Mechanical Engineering
2. GE Aircraft Engines, Lynn, MA (United States)

Leading edge cooling cavities in modern gas turbine blades play an important role in maintaining the leading edge temperature at levels consistent with air foil 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, {alpha}, 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.

• Sponsoring Organization: USDOE
• OSTI ID: 516732
• Report Number(s): CONF-950629--
• Journal Information: Journal of Turbomachinery, Journal Name: Journal of Turbomachinery Journal Issue: 3 Vol. 119; ISSN JOTUEI; ISSN 0889-504X
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
COOLING SYSTEMS
DUCTS
FINS
FORCED CONVECTION
FRICTION FACTOR
GAS TURBINE ENGINES
HEAT TRANSFER
TURBINE BLADES