Characteristics of swirling flames issuing from vane swirlers

Bafuwa, G. G (1970) Characteristics of swirling flames issuing from vane swirlers. PhD thesis, University of Glasgow.

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Abstract

The research work described in this thesis is a continuation of the previous studies carried out in the University of Glasgow on swirling jets issuing from vane swirlers. A test-rig suitable for investigations of combustion systems was designed. The vane swirlers used for the investigations were to the same design as those used by Mathur (5) for investigating cold swirling jets. The measuring instruments were calibrated and the analysis for the temperature correction due to radiation from the thermocouple bead was carried out. For all the experiments, premixed stream of town gas and air was used. Flame stabilisation tests were conducted mainly with hubless swirlers. With the hubless swirlers, stable flames are held at the junction of the swirler vane tips. With each of the annular swirlers, the chemical reaction started from inside the swirler tube. The results of the tests show that highly stable flames are obtainable with vane swirlers. The width of the stable flame region of the stability limits loop increases with swirl although for any given flow velocity, the fuel/air ratios at weak and rich blow-off limits increase with swirl. For flames issuing from swirlers with vane angles of 70 and 75 degrees with both geometries, wall flame jets were formed. The aerodynamic measurements were made v/ith hubless and annular swirlers. The analysis of the results show a strong dependence of the flow distributions in the flow field on the sv/irler exit conditions. As the rotational energy increases, a greater proportion of the nozzle fluid is forced into the outer part of the jet by the centrifugal forces. This concentration of stream lines causes increases in the flow velocities at those radial points in the swirler flow section, as a result of which the static pressures at these points drop. The effect of this is that the maximum axial velocity components, temperatures and minimum static pressures are displaced from the jet axis near the swirler exit. The radial displacements of these aerodynamic variables increase with swirl. All the variables generally decay as the axial distance from the swirler exit increases and the rates of decay depend on the dwirl number. The maximum values of the above parameters on cross-sectional planes (minimum for pressure) ultimately tend to the jet axis and the positions at which the values reach the axis depend on swirl. Throughout the lengths of the jets investigated, the static pressures remain subatmospheric. The minimum swirler vane an.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: R S Silver
Keywords: Mechanical engineering, Fluid mechanics
Date of Award: 1970
Depositing User: Enlighten Team
Unique ID: glathesis:1970-74183
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 23 Sep 2019 15:33
Last Modified: 23 Sep 2019 15:33
URI: http://theses.gla.ac.uk/id/eprint/74183

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