Augmented heat transfer in a triangular duct by using multiple swirling jets

Journal Article · Sun Aug 01 04:00:00 EDT 1999 · Journal of Heat Transfer

DOI:https://doi.org/10.1115/1.2826033· OSTI ID:687532

Hwang, J J; Cheng, C S ^[1]

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1. Chung-Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Mechanical Engineering

In the modern gas turbine design, the trend is toward high inlet gas temperature (1400--1500 C) for improving thermal efficiency and power density. Here, measurements of detailed heat transfer coefficients on two principal walls of a triangular duct with a swirling flow are undertaken by using a transient liquid crystal technique. The vertex corners of the triangular duct are 45, 45, and 90 deg. The swirl-motioned airflow is induced by an array of tangential jets on the side entries. The effects of flow Reynolds number (8600 {le} Re {le} 21,000) and the jet inlet angle ({alpha} = 75, 45, and 30 deg) are examined. Flow visualization by using smoke injection is conducted for better understanding the complicated flow phenomena in the swirling-flow channel. Results show that the heat transfer for {alpha} = 75 deg is enhanced mainly by the wall jets as well as the impinging jets; while the mechanisms of heat transfer enhancement for {alpha} = 45 and 30 deg could be characterized as the swirling-flow cooling. On the bottom wall, jets at {alpha} = 75 deg produce the best wall-averaged heat transfer due to the strongest wall-jet effect among the three angles ({alpha}) investigated. On the target wall, however, the heat transfer enhancements by swirling flow ({alpha} = 45 and 30 deg) are slightly higher than those by impinging jets ({alpha} = 75 deg). Correlations for wall-averaged Nusselt number for the bottom and target walls of the triangular duct are developed in terms of the flow Reynolds number for different jet inlet angles.

• Sponsoring Organization: USDOE
• OSTI ID: 687532
• Journal Information: Journal of Heat Transfer, Journal Name: Journal of Heat Transfer Journal Issue: 3 Vol. 121; ISSN JHTRAO; ISSN 0022-1481
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
33 ADVANCED PROPULSION SYSTEMS
AUGMENTATION
COOLING
DUCTS
GAS TURBINES
HEAT TRANSFER
JETS
TURBINE BLADES
VORTEX FLOW