Abstract
This study presents the measurements of detailed endwall heat transfer and pressure drop in a pin-®nned trapezoidal duct. The trapezoidal duct is inserted with an in-line pin array of ®ve rows and ®ve columns, with the same spacings between the pins in streamwise and spanwise directions of Sx/d5Sy/d5 2.5. The eects of the lateralow ejection (0< e< 1.0) and ow Reynolds number (6000< Re 40000) are examined. Transient liquid crystal technique is employed to measure the detailed heat transfer on the endwall of a pin®nned trapezoidal duct. Results indicate that the pin-®nned trapezoidal duct of a lateralow rate about e5 0.3 has a local minimum endwall-averaged Nusselt number. In addition, the trapezoidal duct of lateral outlet ow only (e5 1.0) has a highest endwall heat transfer as well as pressure drop. Finally, the correlation of the endwall-averaged heat transfer for the pin-®nned trapezoidal duct is developed by taking account of the lateralow rate and the ow Reynolds number.
Highlights
This study focuses on the internal cooling near the trailing edge of a turbine blade, in which pin ®ns spanning between the suction and Received 15 December 1999; In ®nal form 21 April 2000. * Corresponding author
It was found that the overall heat transfer coecients for short pins were lower than those for long pin ®ns (l/d 8.0)
The trapezoidal duct is inserted with an in-line pin array at a ®xed Reynolds number of Re 40000
Summary
The correlation of the endwall-averaged heat transfer for the pin-®nned trapezoidal duct is developed by taking account of the lateral- ̄ow rate and theow Reynolds number. VanFossen (1982) measured the overall heat transfer coecients in rectangular ducts with staggered arrays of short pin ®ns (0.5 < l/d < 2.0). Metzger et al (1982) studied experimentally the local heat transfer variation in rectangular ducts with a staggered pin array for / Sx d 1.5, and / Sy d 2.5, and l/d 1.0. Metzger et al (1984) further studied the eects of usingattened pins and of varying the orientation of the pin ®n array with respect to the mainow direction on the heat transfer and pressure drops in pin ®nned channels. It was shown that the overall heat transfer for a pin-®nned rectangular channel with lateral ejection holes was lower than that for rectangular channel with no ejection holes. Chyu (1990) used a mass transfer sublimating system to
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