Effects of Pin Detached Space on Heat Transfer and Pin-Fin Arrays
Heat transfer and pressure characteristics in a rectangular channel with pin-fin arrays of partial detachment from one of the endwalls have been experimentally studied. The overall channel geometry (W=76.2 mm, E=25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D=6.35 mm=¼E, three different pin-fin height-to-diameter ratios, H/D=4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin tip and one of the endwalls, i.e., C/D=0, 1, 2, respectively. The Reynolds number, based on the hydraulic diameter of the unobstructed cross-section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain the distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all the pin elements. Experimental results reveal that the presence of a detached space between the pin tip and the endwall has a significant effect on the convective heat transfer and pressure loss in the channel. The presence of pin-to-endwall spacing promotes wall-flow interaction, generates additional separated shear layers, and augments turbulent transport. In general, an increase in detached spacing, or C/D, leads to lower heat transfer enhancement and pressure drop. However, C/D=1, i.e., H/D=3, of a staggered array configuration exhibits the highest heat transfer enhancement, followed by the cases of C/D=0 and C/D=2, i.e., H/D=4 or 2, respectively.
- Research Organization:
- National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States). In-house Research; Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Fossil Energy (FE)
- Contributing Organization:
- National Energy Technology Laboratory University of Pittsburgh Purdue University
- DOE Contract Number:
- DE-FE0004000
- OSTI ID:
- 1081457
- Report Number(s):
- TPR-2767; JHTRAO
- Journal Information:
- Journal of Heat Transfer, Vol. 134, Issue 8; Conference: Transaction of the ASME; ISSN 0022-1481
- Publisher:
- ASME
- Country of Publication:
- United States
- Language:
- English
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