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Title: Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel

Abstract

An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened channel combined with detached pin-fins. 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=[1/4]E, 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/O=0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross ribs, namely the broken rib and full rib are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin-fins. 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 distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all pin elements. The presence ofmore » ribs enhances local heat transfer coefficient on the endwall substantially by approximately 20% to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperform cases with broken ribs or full ribs.« less

Authors:
; ;
Publication Date:
Research Org.:
National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States). In-house Research; National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1129873
Report Number(s):
A-UNIV-PUB-042
Journal ID: ISSN 0889-504X
DOE Contract Number:  
DE-FE0004000
Resource Type:
Journal Article
Journal Name:
Journal of Turbomachinery
Additional Journal Information:
Journal Volume: 135; Journal Issue: 2; Journal ID: ISSN 0889-504X
Publisher:
American Society of Mechanical Engineers (ASME)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; Turbines, cooling, heat transfer

Citation Formats

Siw, Sin Chien, Chyu, Minking K., and Alvin, Mary Anne. Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel. United States: N. p., 2012. Web. doi:10.1115/1.4006567.
Siw, Sin Chien, Chyu, Minking K., & Alvin, Mary Anne. Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel. United States. doi:10.1115/1.4006567.
Siw, Sin Chien, Chyu, Minking K., and Alvin, Mary Anne. Thu . "Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel". United States. doi:10.1115/1.4006567.
@article{osti_1129873,
title = {Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel},
author = {Siw, Sin Chien and Chyu, Minking K. and Alvin, Mary Anne},
abstractNote = {An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened channel combined with detached pin-fins. 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=[1/4]E, 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/O=0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross ribs, namely the broken rib and full rib are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin-fins. 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 distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all pin elements. The presence of ribs enhances local heat transfer coefficient on the endwall substantially by approximately 20% to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperform cases with broken ribs or full ribs.},
doi = {10.1115/1.4006567},
journal = {Journal of Turbomachinery},
issn = {0889-504X},
number = 2,
volume = 135,
place = {United States},
year = {2012},
month = {11}
}