0
Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

Characteristics of Flow and Flame Behavior Behind Rifled/Unrifled Nozzles

[+] Author and Article Information
Kuo C. San1

Department of Aviation and Communication Electronics, Air Force Institute of Technology, Kaohsiung, Taiwan 820, R.O.C.kcsan@mail.afats.khc.edu.tw

Hung J. Hsu

Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung, Taiwan 202, R.O.C.

1

Corresponding author.

J. Eng. Gas Turbines Power 131(5), 051501 (May 22, 2009) (12 pages) doi:10.1115/1.3078388 History: Received June 15, 2008; Revised November 30, 2008; Published May 22, 2009

A novel rifled nozzle was installed behind a conventional combustion exhauster to improve combustion efficiency. The rifled nozzles improve the momentum transmission, turbulent strength, and mixing efficiency between the central jet and annular jet. The flow characteristics behind the nozzles (rifled and unrifled) were visualized and detected using the smoke-wire flow visualization, particle image velocimetry, and hot-wire anemometry. The cold flow structures were categorized into four modes—jet flow, single bubble, dual bubble, and turbulent flow. The topological scheme was adopted to analyze and verify these flow modes. The flame structures behind the nozzles (rifled and unrifled) are classified into three modes—jet flame, flickering flame, and turbulent flame—using the direct-photo visualization. The flame height of a 12-rifled nozzle is decreased by about 50% under that of an unrifled nozzle. The flame shedding frequency declines rapidly in the flickering flame mode and the relationship between the Strouhal number (Sr) and annular velocity (ua) is Sr=0.0238+0.13/ua.

FIGURES IN THIS ARTICLE
<>
Copyright © 2009 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Experimental setup

Grahic Jump Location
Figure 2

Streak flow patterns at uc=2.06 m/s: (a)–(f) for a unrifled nozzle, (g)–(l) for a 6-rifled nozzle, and (m)–(r) for a 12-rifled nozzle

Grahic Jump Location
Figure 3

Distribution of characteristic cold flow modes

Grahic Jump Location
Figure 4

Velocity vector fields and streamline patterns at uc=2.06 m/s: (a) jet-flow mode (ua=0), (b) single bubble mode (ua=0.23 m/s), (c) dual bubble mode (ua=0.42 m/s), and (d) turbulent flow mode (ua=1.22 m/s)

Grahic Jump Location
Figure 5

Topological flow structures at uc=2.06 m/s: (a) jet-flow mode (ua=0), (b) single bubble mode (ua=0.23 m/s), (c) dual bubble mode (ua=0.42 m/s), and (d) turbulent flow mode (ua=1.22 m/s)

Grahic Jump Location
Figure 6

Photographs of normalized flame height (x/D) for a unrifled nozzle at uc=2.06 m/s: (a) ua=0, (b) ua=0.23, (c) ua=0.42, (d) ua=1.22, (e) ua=1.98, and (f) ua=2.16 m/s

Grahic Jump Location
Figure 7

Photographs of normalized flame height (x/D) at uc=2.06 m/s: (a)–(c) for a 6-rifled nozzle and (d)–(f) for a 12-rifled nozzle

Grahic Jump Location
Figure 8

Distribution of characteristic flame configurations

Grahic Jump Location
Figure 9

Normalized flame height (Hf/D) against ua at uc=0.58 m/s (void symbols) and uc=2.06 m/s (solid symbols)

Grahic Jump Location
Figure 10

Velocity profiles of flame shedding for (a) laminar, (b) subcritical, and (c) transitional modes

Grahic Jump Location
Figure 11

Distribution of flame shedding modes

Grahic Jump Location
Figure 12

Distributions of power spectrum (log Φ) versus logarithmic frequency (log f) for flame shedding in (a) laminar, (b) subcritical, and (c) transitional modes

Grahic Jump Location
Figure 13

Distributions of probability density function as a function of u′ for flame shedding in (a) laminar, (b) subcritical, and (c) transitional modes

Grahic Jump Location
Figure 14

Distributions of (a) f versus ua and (b) Sr versus ua

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In