 

Document Type

Journal Article

Publication Title

Experimental Thermal and Fluid Science

Publisher

Elsevier

School

School of Engineering

RAS ID

62447

Funders

Higher Education Commission (HEC) Pakistan / Edith Cowan University

Abstract

Bluff-body stabilised annular jets possess simple, well-defined, axisymmetric geometry, yet exhibit highly complex flow fields, are susceptible to asymmetry at larger blockage ratios, and embody both complex zones and shear layers. Practical annular combustors feature swirl and a central jet which further complicates the flows. Despite the importance of asymmetry in practical combustor design, a systematic investigation for the role of flow regime (transitional, turbulent), Reynolds number, swirl number, or central jets on asymmetry remains lacking. In this study, two-dimensional time-averaged planar particle image velocimetry measurements are conducted to resolve the intrinsic asymmetry associated in transitional (Res = 2700) and turbulent (Res = 17,800 and 35,500) bluff-body stabilised confined annular jets. Experiments are conducted on non-swirling (S = 0) and swirling annular jets (with S = 0.3), both operating independently and with the addition of a turbulent central jet (Res = 10,400). Constant temperature anemometry measurements resolve boundary conditions at the exit of annulus and an Asymmetry Index is presented.

Results show that swirl significantly mitigates asymmetric vortex shedding and restores annular jet symmetry. Quantification (at x/D = 1, r/D = 0.5) reveals that turbulent swirling annular jets demonstrates a 42 % (for Res = 17,800) and 78.6 % (for Res = 35,500) reduction in asymmetry compared to non-swirling annular jets. Whereas, swirling annular jets under transitional flow regime show a negligible impact on the flow asymmetry. In addition to this, increasing the Reynolds number from Res= 2,700 to 17,800 results in a 36.2 % and 58.7 % decrease in the asymmetry for non-swirling and swirling annular jets, respectively. A further increase to Res = 35,500 brings an additional 68.6 % decrease in the asymmetry for swirling annular jets, showing that swirl in combination with high turbulence restores and maintains symmetry in bluff-body stabilised annular jets. Moreover, at medium turbulence (Res = 17,800), the non-swirling annular jet with a superimposed turbulent jet exhibits a nearly axisymmetric flow behaviour compared to stand-alone non-swirling annular jet.

DOI

10.1016/j.expthermflusci.2023.111063

Creative Commons License


This work is licensed under a Creative Commons Attribution 4.0 License.

Included in

Engineering Commons

Share

 
COinS
 
 
 
{"cc_re__cc_re__cc_by_4_0": [" class='field-heading'>Related Publications</h2>\n<p>Gillani, S. E. (2023). <em>Downstream air dilution and biomass pulverisation into bluff-body and swirl stabilised confined turbulent jets</em>. Edith Cowan University. Retrieved from <a href=\"https://ro.ecu.edu.au/theses/2726\" target=\"_blank\" title=\"link to thesis\">https://ro.ecu.edu.au/theses/2726</a></p>\n</div>\n<div class='clear'></div>\n<div id='distribution_license' class='element'>\n<h2 class='field-heading'>Creative Commons License</h2>\n<p><a href=\"http://creativecommons.org/licenses/by/4.0/\"><img alt=\"Creative Commons Attribution 4.0 License\" src=\"http://i.creativecommons.org/l/by/4.0/88x31.png\" /></a><br />This work is licensed under a <a href=\"http://creativecommons.org/licenses/by/4.0/\">Creative Commons Attribution 4.0 License</a>.</p>\n</div>\n<div class='clear'></div>\n</div>\n    </div>\n    <div id='beta_7-3'>\n<!-- FILE: /srv/sequoia/main/data/assets/site/info_box_7_3.inc --><!-- FILE: /srv/sequoia/main/data/assets/site/openurl.inc -->\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n<!-- FILE: /srv/sequ", "Cowan University. Retrieved from <a href=\"https://ro.ecu.edu.au/theses/2726\" target=\"_blank\" title=\"link to thesis\">https://ro.ecu.edu.au/theses/2726</a></p>\n</div>\n<div class='clear'></div>\n<div id='distribution_license' class='element'>\n<h2 class='field-heading'>Creative Commons License</h2>\n<p><a href=\"http://creativecommons.org/licenses/by/4.0/\"><img alt=\"Creative Commons Attribution 4.0 License\" src=\"http://i.creativecommons.org/l/by/4.0/88x31.png\" /></a><br />This work is licensed under a <a href=\"http://creativecommons.org/licenses/by/4.0/\">Creative Commons Attribution 4.0 License</a>.</p>\n</div>\n<div class='clear'></div>\n</div>\n    </div>\n    <div id='beta_7-3'>\n<!-- FILE: /srv/sequoia/main/data/assets/site/info_box_7_3.inc --><!-- FILE: /srv/sequoia/main/data/assets/site/openurl.inc -->\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n<!-- FILE: /srv/sequoia/main/data/assets/site/info_box_7_3.inc (cont) -->\n<!-- FILE: /srv/sequoia/main/data/assets/site/ir_download_link.inc -->\n\n\n\n\n\n\n\n\n\n\t\n\t\n\t\n    \n    \n    \n\t\n\t\t\n\t\t\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\n<!-- FILE: /srv/sequoia"], "copyright__copyright__copyright": ["ion with high turbulence restores and maintains symmetry in bluff-body stabilised annular jets. Moreover, at medium turbulence (Res = 17,800), the non-swirling annular jet with a superimposed turbulent jet exhibits a nearly axisymmetric flow behaviour compared to stand-alone non-swirling annular jet.\n\nDOI\n\n10.1016/j.expthermflusci.2023.111063\n\nCreative Commons License\n\n\nThis work is licensed under a Creative Commons Attribution 4.0 License.\n\nIncluded in\n\nEngineering Commons\n\nShare\n\n\u00a0\nCOinS\n\u00a0\n\u00a0\n\u00a0", "ion with high turbulence restores and maintains symmetry in bluff-body stabilised annular jets. Moreover, at medium turbulence (Res = 17,800), the non-swirling annular jet with a superimposed turbulent jet exhibits a nearly axisymmetric flow behaviour compared to stand-alone non-swirling annular jet.\n\nDOI\n\n10.1016/j.expthermflusci.2023.111063\n\nCreative Commons License\n\n\nThis work is licensed under a Creative Commons Attribution 4.0 License.\n\nIncluded in\n\nEngineering Commons\n\nShare\n\n\u00a0\nCOinS\n\u00a0\n\u00a0\n\u00a0", "ion with high turbulence restores and maintains symmetry in bluff-body stabilised annular jets. Moreover, at medium turbulence (Res = 17,800), the non-swirling annular jet with a superimposed turbulent jet exhibits a nearly axisymmetric flow behaviour compared to stand-alone non-swirling annular jet.\n\nDOI\n\n10.1016/j.expthermflusci.2023.111063\n\nCreative Commons License\n\n\nThis work is licensed under a Creative Commons Attribution 4.0 License.\n\nIncluded in\n\nEngineering Commons\n\nShare\n\n\u00a0\nCOinS\n\u00a0\n\u00a0\n\u00a0"]}