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Characterization of ALM swirl burner surface roughness and its effect on flame stability using high-speed diagnostics

Runyon, Jon, Giles, Anthony, Marsh, Richard, Pugh, Daniel, Goktepe, Burak, Bowen, Philip and Morris, Steve 2019. Characterization of ALM swirl burner surface roughness and its effect on flame stability using high-speed diagnostics. Journal of Engineering for Gas Turbines and Power , GTP-19-1389. 10.1115/1.4044950

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Abstract

In this study, two Inconel 625 swirl nozzle inserts with identical bulk geometry were constructed via Additive Layer Manufacturing (ALM) for use in a generic gas turbine swirl burner. Further post-processing by grit blasting of one swirl nozzle insert results in a quantifiable change to the surface roughness characteristics when compared with the unprocessed ALM swirl nozzle insert or a third nozzle insert which has been manufactured using traditional machining methods. An evaluation of the influence of variable surface roughness effects from these swirl nozzle inserts is therefore performed under preheated isothermal and combustion conditions for premixed methane-air flames at thermal power of 25 kW. High-speed velocimetry at the swirler exit under isothermal conditions gives evidence of the change in near-wall boundary layer thickness and turbulent fluctuations resulting from the change in nozzle surface roughness. Under atmospheric combustion conditions, this influence is further quantified using a combination of dynamic pressure, high-speed OH* chemiluminescence, and exhaust gas emissions measurements to evaluate the flame stabilization mechanisms at the lean blowoff and rich stability limits. Notable differences in flame stabilization are evident as the surface roughness is varied, and changes in rich stability limit were investigated in relation to changes in the near-wall turbulence intensity. Results show that precise control of in-process or post-process surface roughness of wetted surfaces can positively influence burner stability limits and NOx emissions and must therefore be carefully considered in the ALM burner design process as well as CFD models.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Engineering
Publisher: ASME
ISSN: 1528-8919
Funders: EPSRC
Date of First Compliant Deposit: 29 August 2019
Date of Acceptance: 2 July 2019
Last Modified: 30 Nov 2019 06:43
URI: http://orca-mwe.cf.ac.uk/id/eprint/125188

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